Disk brakes for tandems
Anita Paulsen
I'm looking for ideas on how to increase our tandem stopping power. We
have Scott rim brakes which stop us okay, but twice now we've blown front
tubes (one a rather spectacular full tire explosion) due to rim
overheating. I'm running extra heavy duty tubes now, but every time I
suggest a ride now my wife turns pale.
I have a drum brake that I'm reluctant to install because it's way
heavy. I'd like one of the new disk brakes, but in the review in
the latest issue of Bicycling it seemed they were only for mountain
suspension forks with special bosses to attach them. Is there a way to
attach a disk brake on a road fork? How about the rear - the hub (Phil
Wood) is already threaded for a drum, so is it possible to install a disk
there? Other ideas?
Thanks,
Peter Rummel
Phil Feldman
>How about the rear - the hub (Phil Wood) is already threaded for a drum, so
is it possible to install a disk there? Other ideas?
I have had Hope disks on my tandem for three years. They work very well. To
get them on your bike, you'll have to get the mounting hardware brazed on to
the fork and/or rear triangle. If you're only going to have one, get a front
disk.
Hope this helps,
Phil
Eric Salathe
Anita Paulsen wrote:
> I'm looking for ideas on how to increase our tandem stopping power. We
> have Scott rim brakes which stop us okay, but twice now we've blown front
> tubes (one a rather spectacular full tire explosion) due to rim
> overheating. I'm running extra heavy duty tubes now, but every time I
> suggest a ride now my wife turns pale.
> I have a drum brake that I'm reluctant to install because it's way
> heavy.
Hub brakes will not increase your `stopping power'. What you have are
already 559 or 622 mm ventilated disk brakes. Small-diameter disks must
generate significantly more friction at the disk to equal the braking
force at the tire, and brick on steel is not as good as rubber on
aluminum. Also, you cannot put a hub brake on a fork not designed to
take the force at its tips.
A rear hub brake in addition to the rim brakes set to a third control
(eg a bar-end shift lever on either captain or stoker bars) will not
impede your current brakes and allow you to use it as a drag to control
speed and eliminate over-heating on long descents. The ARAI drum is the
best and cheapest, and probably because it is so heavy. You need the
bulk to provide the cooling fins and a thermal barrier to protect the
hub bearing. We ride extensively in the mountains, and I would be
reluctant to go without the ARAI, even unloaded.
When fellow riders raise eyebrows over the weight (and that of the
2-legged kickstand, fenders, and 48-spoke wheel), I just tell them we
take all that off when we ride with fast groups. The weight is a lot
less significant than you think -- it won't keep you from where you're
going or get you dropped.
Since it isn't clear from you post, if your blowoffs are not the result
of long slow descents (ie with several minutes steady braking), then
your problem is probably unrelated to brakes. There could be a problem
with the rims that lets the tire bead fall out easily.
--
,
Eric P. Salathe, Jr. sal...@atmos.washington.edu
Seattle WA
Matt O'Toole
Mark Hickey wrote in message <34d3924f...@usenet.kornet.nm.kr>...
>Does it really matter in terms of total heat generation if you're
>applying the brakes continuously or applying twice as much braking for
>half the time? Unless I'm missing something very basic, the end
>result is going to be the same in terms of tire and rim heating.
You're right, the amount of energy converted to heat is the same, but by
allowing the rim to cool for short periods, it won't reach as high a peak
temperature.
Matt O.
thorsten schaette
On 30 Jan 1998 17:08:34 GMT, sno...@eskimo.com (Anita Paulsen) wrote:
> I'm looking for ideas on how to increase our tandem stopping power. We
>have Scott rim brakes which stop us okay, but twice now we've blown front
>tubes (one a rather spectacular full tire explosion) due to rim
>overheating. I'm running extra heavy duty tubes now, but every time I
>suggest a ride now my wife turns pale.
> I have a drum brake that I'm reluctant to install because it's way
>heavy. I'd like one of the new disk brakes, but in the review in
>the latest issue of Bicycling it seemed they were only for mountain
>suspension forks with special bosses to attach them. Is there a way to
>attach a disk brake on a road fork? How about the rear - the hub (Phil
>Wood) is already threaded for a drum, so is it possible to install a disk
>there? Other ideas?
>
>Thanks,
>Peter Rummel
Hi Peter
DONT !!!!
at least not yet ! :-)
there is no disk brake in the world, who would survive the Tandem
treatment. Thats one reason we at Magura are pushing so much for the
braze ons at fork or frame. ( and tell Tandem builders not to even
think about disk brakes and those braze ons )
If you are a PRO and would riding a Tandem in a Downhill , Yes our
brake would manage it. No problem ! But as a Pro you could also ask to
have the thing inspected after every run, and parts ( rotors )
exchanged. Obviously that would be a very costly adventure for you !
Now, I cannot help to say ,that you should try our rim brakes on your
tandem. Although scott brakes are not a bad choice for a tandem, they
work differently. And the real problem is the way you use the brakes.
dont use the brakes as dragbrakes, but controlled, even at times, hard
braking. lets say, in a studder mode ( on off on off on off ) dont
just slow down continuesly, but brake hard and than let off. Also
pump up your chest and use the wind to slow you. ( this takes top
speeds down without heating up anything )
Also with our rim brakes, you can install a second lever ( in line )
for your stoker. She can slow down the rear wheel also, if she feels
you are goin to fast. ( again tell her , not to drag the brakes )
This will give her a little control and makes her feel much better.
( And thats what Tandem riding is all about. Isnt it. )
You will find out , that she will not use the brake much often,
just the idea, that she can , is important !
Again, if somebody teels you that this or that diskbrake will work on
a Tandem ........... RUN !
The only way, which I liked was to add a real dragbrake like the old
ARAI drum brake to the rear wheel. And the beauty is, that she should
fit on your hub already. Now this brake is a dragbrake and not super
powerful. No way.... to block the wheel or something drastic. Just a
good dragbrake ( if you really need one ??)
Ok I think I saved you thousands of dollars and a lot of grief, so
send the check to .......... just kiddin
Happy Trails together
Magura USA
Thorsten
Jobst Brandt
Phil Feldman writes:
>> How about the rear - the hub (Phil Wood) is already threaded for a
>> drum, so is it possible to install a disk there? Other ideas?
> I have had Hope disks on my tandem for three years. They work very
> well. To get them on your bike, you'll have to get the mounting
> hardware brazed on to the fork and/or rear triangle. If you're only
> going to have one, get a front disk.
A hub brake on the front wheel requires a torque strut to prevent
breaking off the fork end. Forks are generally not made to take up
torque in bending at the small end. For this reason, most tandems
use a hub brake in the rear where these forces can be adequately taken
by the frame. Besides, the response of caliper rim brakes is more
direct and preferable for controlling the bicycle, while absorbing
energy on longer descents is best done with a brake that doesn't heat
the rims.
Jobst Brandt <jbr...@hpl.hp.com>
Mark Hickey
gor...@omegabbs.com (thorsten schaette) wrote:
>dont use the brakes as dragbrakes, but controlled, even at times, hard
>braking. lets say, in a studder mode ( on off on off on off ) dont
>just slow down continuesly, but brake hard and than let off.
It's always been my (untested) assumption that there is no advantage
to pumping brakes on a bicycle, unless the end result is that you are
allowing the bike to roll faster, thus using less overall braking -
hence creating less heat. (Note: I'm not talking about trying to
control an impending lockup).
Does it really matter in terms of total heat generation if you're
applying the brakes continuously or applying twice as much braking for
half the time? Unless I'm missing something very basic, the end
result is going to be the same in terms of tire and rim heating.
Mark Hickey
Habanero Cycles
htttp://www.cynetfl.com/habanero/
thorsten schaette
On Sat, 31 Jan 1998 21:50:50 GMT, mhi...@cynetfl.com (Mark Hickey)
wrote:
>Does it really matter in terms of total heat generation if you're
>applying the brakes continuously or applying twice as much braking for
>half the time? Unless I'm missing something very basic, the end
>result is going to be the same in terms of tire and rim heating.
>
>Mark Hickey
>Habanero Cycles
>htttp://www.cynetfl.com/habanero/
Hi Mark
the idea is to allow the rims to cool down. Of course you have a
point with your statement with twice as much braking ( friction) but
the trick is, that at higher speeds you have more wind resistance and
even a little more rolling resistance ( although nothing compared to
the wind ) therefore you actually dont use the brakes that much .
Even on Tandems the heat at the rims is actually not such a big
problem as it seems sometimes.
It used to be much more serious in times where tubulars ruled. There
the tireglue got warm and the tire turned on the rim, ripped the
valve.
With good clincher tires / tubes and good care this problem is
highly overstated. Yes in most instances it is 'just' a blown
innertube ( or even a leaking one ) But that doesnt make for good
storytelling . The macho approach of cooking a rim and therefore
blowing a tire sounds so much better.
I have sold a lot of tandems in my years and have built ( overseen the
construction ) some really neat tandems . ( some ten years ago we
organized a tandem race in ffront of the tour de france peleton with
blind stokers. "My" tandems won 4 out of the first 10 places ! ( Im
still proud of the teams ! The really fun part was, that the tandems
were so fast, they reached the end of the endless advertising parades
in front of them, and the race official in the lead car was not a
bright person at all. So it happened that half the field , some 20
tandems, struggled through the caravan, before they finally got open
road in front of them. Than, they arrived one hour before schedule.
The other tandem I was involved with, was a speed tandem, driven by
two crazy frenchguys, actually the stoker was blind. The single speed
tandem had 172 teeth in front and 13 in the rear !!! They travelled
behind a car on the french highway ( yes a public road !!! ) and
reached someting like 105 miles or so. Actually those guys had one
maillard drum brake ( higly uneffective !) and tubulars. Test at the
Nuerburgring earlier, showed that the tubulars were seperating from
the rim at about 90 mph. We solved the problem with wrapping duct tape
around the tire and rim. The tape dissapeared rather rapidly on the
tire contact area, but just had enough strength to 'clamp' the tire to
the rim. Crazy stuff.
Happy Trails
Thorsten
William Herrera
On Fri, 30 Jan 1998 23:04:29, Eric Salathe <sal...@u.washington.edu>
wrote:
> A rear hub brake in addition to the rim brakes set to a third control
> (eg a bar-end shift lever on either captain or stoker bars) will not
> impede your current brakes and allow you to use it as a drag to control
> speed and eliminate over-heating on long descents. The ARAI drum is the
> best and cheapest, and probably because it is so heavy. You need the
> bulk to provide the cooling fins and a thermal barrier to protect the
> hub bearing. We ride extensively in the mountains, and I would be
> reluctant to go without the ARAI, even unloaded.
I like the setup where the rear addtional brake (a disc in our case)
is controlled by a thumb index shifter-type lever on the _stoker's_
handlebar. On long twisting descents, it keeps the hands from getting
tired to set it to drag at a fixed rate.
And our stoker likes the extra control of having their own brake :).
---
Note: The above address is spamblocked.
The real reply-to is: wherrera (at) lookout.com
John Serafin
mhi...@cynetfl.com (Mark Hickey) writes:
>gor...@omegabbs.com (thorsten schaette) wrote:
>>dont use the brakes as dragbrakes, but controlled, even at times, hard
>>braking. lets say, in a studder mode ( on off on off on off ) dont
>>just slow down continuesly, but brake hard and than let off.
>It's always been my (untested) assumption that there is no advantage
>to pumping brakes on a bicycle, unless the end result is that you are
>allowing the bike to roll faster, thus using less overall braking -
>hence creating less heat. (Note: I'm not talking about trying to
>control an impending lockup).
>Does it really matter in terms of total heat generation if you're
>applying the brakes continuously or applying twice as much braking for
>half the time? Unless I'm missing something very basic, the end
>result is going to be the same in terms of tire and rim heating.
You must have been on vacation, busy, asleep, or failed to notice it
buried in some other thread the last time this came up.
At a steady speed with steady braking that will overheat a tire, pumping
the brakes to maintain the same average speed will put just as much
heat into the tires in the same amount of time (longer than a pumping
cycle). Thus, pumping brakes will not prevent overheating.
One strategy that might work is to leave the brakes off as long as possible,
then brake hard to make a turn, release as soon as possible, repeat as
necessary. This gives a higher average speed and I don't think anyone
would call it pumping. For a steep enough hill, the tires will still overheat.
Diligent searching can probably turn up a post by Jobst Brandt saying as
much.
Around here (SF Bay area), there are three types of tandem teams without
drag brakes:
1. Really fast racer types with excellent descending skills.
2. Those that avoid steep downhills.
3. Those about to have a blowout.
I've known several type 3 teams and suspect that type 1's are really type 2's,
but they can do steeper hills than most can without a drag brake, but they
don't even consider some other hills that I don't give a second thought to.
Ok, there is type 4 that don't ride hills at all, but then, none of the above
matters for them.
--
John P. Serafin | Operating a bicycle is more like driving than riding.
jps at pobox com | Operating an automobile is more like riding than driving.
Adam Rice
On 30 Jan 1998 17:08:34 GMT, sno...@eskimo.com (Anita Paulsen) wrote:
> I'm looking for ideas on how to increase our tandem stopping power. We
>have Scott rim brakes which stop us okay, but twice now we've blown front
>tubes (one a rather spectacular full tire explosion) due to rim
>overheating. I'm running extra heavy duty tubes now, but every time I
>suggest a ride now my wife turns pale.
> I have a drum brake that I'm reluctant to install because it's way
>heavy. I'd like one of the new disk brakes, but in the review in
>the latest issue of Bicycling it seemed they were only for mountain
>suspension forks with special bosses to attach them. Is there a way to
>there? Other ideas?
Thorsten may be right about disk brakes. I dunno. I do know that recumbent
tandem trikes are often built with two disk brakes in front (since they
have two wheels in front), and are known to have wicked stopping power.
Another option that comes to mind is building a front wheel with a
drum-brake hub, from Sachs or something. This is not the same as the Arai
drum, and not as heavy--the mechanism is in the hubshell, not attached to
the side. I suppose you could even use it in concert with a caliper brake.
Even if you did wind up using the Arai, sacrificing some weight to able to
ride is not a bad tradeoff.
Adam Rice | adam...@crossroads.net
Austin TX USA | http://www.crossroads.net
Chris Neary
adam...@crossroads.net (Adam Rice) wrote:
>Another option that comes to mind is building a front wheel with a
>drum-brake hub, from Sachs or something. This is not the same as the Arai
>drum, and not as heavy--the mechanism is in the hubshell, not attached to
>the side. I suppose you could even use it in concert with a caliper brake.
You'd have to add a braze-on to the front fork to take the torque from
the drum, and be sure the fork was capable of handling this loading.
Front wheel drum-brake hubs are standard on Tandem Twos'days. I know one
couple who wanted extra braking power, so they added a disk (sorry, I
don't know the brand) to the rear wheel.
They use bar end shifters. One brake lever controls both the rim brakes
while the other lever controls both the disk and drum.
This couple has over 20 years of tandeming experience, so I trust they
know what is best for them.
Green Gear considered it their most challenging tandem order ever.
Regards,
Chris Neary
dia...@aimnet.com
Chris & Tracey - 1997 Tandem Two'sDay
boyd
On Sat, 31 Jan 1998, Mark Hickey wrote:
> gor...@omegabbs.com (thorsten schaette) wrote:
>
> >dont use the brakes as dragbrakes, but controlled, even at times, hard
> >braking. lets say, in a studder mode ( on off on off on off ) dont
> >just slow down continuesly, but brake hard and than let off.
>
> It's always been my (untested) assumption that there is no advantage
> to pumping brakes on a bicycle, unless the end result is that you are
> allowing the bike to roll faster, thus using less overall braking -
> hence creating less heat. (Note: I'm not talking about trying to
> control an impending lockup).
I found Thorsten's posting interesting and, unlike Mark Hickey, in keeping
with my own experience. My brakes (loaded touring rather than tandem) seem
to hold up better on long descents if I brake hard intermittently rather
than using them as drag brakes.
> Does it really matter in terms of total heat generation if you're
> applying the brakes continuously or applying twice as much braking for
> half the time? Unless I'm missing something very basic, the end
> result is going to be the same in terms of tire and rim heating.
The amount of energy that must be gotten rid of is obviously the same with
either method. That doesn't mean tire and rim heating will be the same. I
can see two ways in which intermittent braking differs from drag braking.
The first way is that heat generated in spikes will heat the tire and rim
differently than heat generated continuously. The second is that
intermittent braking leads to more speed variations and therefore to more
energy loss to air resistance.
In the heating scenario two things are different: surface temperature and
heat flow from the braking surface into the rest of the wheel. If I
suddenly make the braking surface hot by hard braking, more of that heat
will go into the air from the hot surface and less will go into the wheel
assembly than if I continuously keep the surface 'warm' by using it in
drag braking.
As Mark H. mentions, in dealing with energy loss to air resistance, while
my average speed may be the same for both braking methods, my peak speed
will be (much in my experience) higher. Since air drag is non linear, and
goes up quite rapidly with speed, my net loss of energy to air drag will
be higher with intermittent braking. This means less energy to dissapate
with my brakes. I'm not sure about the size of this effect, but it could
be significant.
Based on these arguments and my own experience, I think I am less likely
to suffer delterious effects, like a blowout or brake fading, when I brake
hard intermittently than when I drag my brakes. Of course on a good road
surface it also more fun to go fast and then brake hard than to drag
brake!
Mark <bo...@cs.unca.edu>
Charles Maurer
In article <34d44a4f...@news.ncal.verio.com>, dia...@aimnet.com
(Chris Neary) wrote:
> Front wheel drum-brake hubs are standard on Tandem Twos'days. I know one
> couple who wanted extra braking power, so they added a disk (sorry, I
> don't know the brand) to the rear wheel.
Hub brakes will have a greater effect on a Two'sDay because of its smaller
wheels but, as your friends found out, even this is not sufficient for a
drum on a tandem.
When I spoke to Green Gear about putting a disc on front of a Two'sDay,
they told me that they ceased doing so. They had too many disintegrate
under the load. St. John Street Cycle, who ultimately made our tandem,
said they would not put one on the rear either.
In any case, strong rear brakes on a tandem are not very useful. That's
because at maximum deceleration of a tandem (ca. 0.8g, the limit of
tires), the rear wheel has virtually no load on it. All the rear brakes
do, really, is spell the front under light or prolonged breaking.
However, if the front brakes are overheating, spelling the front is
essential; hence a drag. This is usually an Arai drum because it is
substantial and has large fins to dissipate heat. On a long descent it
needs those fins. It gets *very* hot. To use a finless Sachs drum as a
brake, as somebody suggested, or grinding off the Arai's fins, which one
American manufacturer does, is to vitiate it. To do this to save a few
ounces off a total mass of 400 pounds to 450 pounds is daft. Even more
daft, if the front brakes are overheating, is to leave the whole thing
off.
--
Charles Maurer
5 Grandview Court
Dundas, ON L9H 5C8
Canada
telephone & fax: 905.627.7035
Brodkin Panu
thorsten schaette (gor...@omegabbs.com) wrote:
: DONT !!!!
: at least not yet ! :-)
: there is no disk brake in the world, who would survive the Tandem
: treatment. Thats one reason we at Magura are pushing so much for the
Maguras disk brake can´t stand the Tandem treatment !?!?!?!
I think that at least all other disc brakes can !! (Those brakes aren´t
so different from brakes used in mopeds or motorcycles ... And the
absorbed energy is also much less than in many other applications.)
And how those brakes CAN handle downhill descents at the mountains,
but NOT at the streets ?!? - I don´t really get it ...
: braze ons at fork or frame. ( and tell Tandem builders not to even
: think about disk brakes and those braze ons )
OK - I´m sure that those braze ons or other adaptors could break
(if not properly made ..). But welded mounts on steel or alu frames
can survive. (And how about those few MTB-tandems !!!)
: If you are a PRO and would riding a Tandem in a Downhill , Yes our
: brake would manage it. No problem ! But as a Pro you could also ask to
: have the thing inspected after every run, and parts ( rotors )
: exchanged. Obviously that would be a very costly adventure for you !
Magura disk brakes must be inspected during the ride ??? (And between
the rides bike should be anyway checked ..) And Magura rotors doesn´t
last ??? (Other brands rotors last but brake pads is changed ..)
I´m happy to own non-Magura disc brake ;-)
(.. but I still hope that Magura is going to produce descent XC-MTB
disc brake for mass production bikes - similar for low end Magura
rim brakes ... I think that rim brakes should have been skipped in
bicycle history ..)
: Happy Trails together
: Magura USA
: Thorsten
--
--------------------------------------------------------------------
Osoite: Panu Brodkin "Erehtyyhän sitä -
Insinöörinkatu 60D247 Useimmiten !!"
33720 Tampere
Email: Panu.B...@cc.tut.fi
--------------------------------------------------------------------
Hans-Joachim Zierke
thorsten schaette schrieb:
> DONT !!!!
> at least not yet ! :-)
> there is no disk brake in the world, who would survive the Tandem
> treatment.
Sure there is.
> Again, if somebody teels you that this or that diskbrake will work on
> a Tandem ........... RUN !
Here I am, and I say, that diskbrakes work on a tandem.
For a couple who rides a loaded tandem in the alps a lot, Mr. Sattler of
Technobull has built the following setup: Two Magura drop bar levers, _two_
Sachs diskbrakes in the front, rear Magura, trailer Magura.
Instead of racks for panniers, he uses a 4 kg campinggear-trailer connected
to a special rack with cardanic connector. The trailer Magura has an
oiltight coupling (good technically, but a mess aethetically, because it it
too big for a bicycle, and looks like Caterpillar hydraulics. He couldn't
get anything smaller). On a five-digit-of-DMs bicycle, aesthetical problems
are real problems for a framebuilder.
Since he builds the front fork himself, and builds the front hub himself,
there is no problem with the double Sachs disk. And while other disks would
run out of lever travel, Magura standard diameter and two Sachs disks
works, though you have to adjust very carefully (and Sachs will say: Don't
do it.)
hajo
Jobst Brandt
Matt O'Toole writes:
>> Does it really matter in terms of total heat generation if you're
>> applying the brakes continuously or applying twice as much braking
>> for half the time? Unless I'm missing something very basic, the
>> end result is going to be the same in terms of tire and rim
>> heating.
> You're right, the amount of energy converted to heat is the same,
> but by allowing the rim to cool for short periods, it won't reach as
> high a peak temperature.
With continuous braking the average temperature is reached, with
pulsed braking, the peak temperature must be higher than the average
because the same amount of energy must be dissipated in a shorter
time. You cannot fool the energy equation. The best you can do is to
allow the bike to roll as fast as is safe and dissipate more energy to
wind drag and then use the brakes only when necessary. This will
reduce peak temperatures.
Jobst Brandt <jbr...@hpl.hp.com>
Jobst Brandt
Mark Hickey writes:
> Does it really matter in terms of total heat generation if you're
> applying the brakes continuously or applying twice as much braking for
> half the time? Unless I'm missing something very basic, the end
> result is going to be the same in terms of tire and rim heating.
Yes, you'll get twice the heat that must be removed by convection.
Jobst Brandt <jbr...@hpl.hp.com>
Jobst Brandt
Charles Maurer writes:
> In any case, strong rear brakes on a tandem are not very useful.
> That's because at maximum deceleration of a tandem (ca. 0.8g, the
> limit of tires), the rear wheel has virtually no load on it. All
> the rear brakes do, really, is spell the front under light or
> prolonged breaking.
That's one of the features of tandems, that with their long wheelbase,
load transfer is greatly reduced and rear wheel braking to control
speed is reasonable and practical. For those who have descended
mountain roads with a series of hairpin turns, this becomes apparent.
Without the hub brake tires become overheated, unseat and blow out,
while with a hub brake in addition to rim brakes, temperatures can be
kept within safe limits.
Jobst Brandt <jbr...@hpl.hp.com>
David Suryan
In article <34d3924f...@usenet.kornet.nm.kr>,
Mark Hickey <mhi...@cynetfl.com> wrote:
>Does it really matter in terms of total heat generation if you're
>applying the brakes continuously or applying twice as much braking for
>half the time? Unless I'm missing something very basic, the end
>result is going to be the same in terms of tire and rim heating.
For those of us that don't use drag brakes, the idea is to
minimize braking. If one we're to descend a road where the
riders feel comfortable going no faster than 20mph, then one
strategy is to drag the brakes so the descent is no faster that
20mph. The other strategy is to let the tandem go fast between
those curves allowing the tandem to reach 40 - 50 mph. When
the curves come, then apply the brakes to slow down to 20 mph.
The average speed is faster thus letting the wind, instead of
the brakes slow the tandem.
Sheldon Brown
> Jobst wrote:
> >With continuous braking the average temperature is reached, with
> >pulsed braking, the peak temperature must be higher than the average
> >because the same amount of energy must be dissipated in a shorter
> >time. You cannot fool the energy equation. The best you can do is to
> >allow the bike to roll as fast as is safe and dissipate more energy to
> >wind drag and then use the brakes only when necessary. This will
> >reduce peak temperatures.
Thorsten Schaette demurred:
> whatabout the cool down inbetween brake sequences ?
> Doesnt that count ?
No, it doesn't. The cooling, by radiation and conduction, occurrs
continuously as long as the rim is hotter than the ambient air, whether
the brake is being applied or not.
Sheldon "Studied Physics In High School, Still Remembers Some" Brown
Newtonville, Massachusetts
+---------------------------------------+
| Whatever became of eternal truth? |
+---------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-1040 FAX 617-244-1041
http://www.sheldonbrown.com/harris
thorsten schaette
On 2 Feb 1998 19:33:57 GMT, jbr...@hpl.hp.com (Jobst Brandt) wrote:
>Matt O'Toole writes:
>
>>> Does it really matter in terms of total heat generation if you're
>>> applying the brakes continuously or applying twice as much braking
>>> for half the time? Unless I'm missing something very basic, the
>>> end result is going to be the same in terms of tire and rim
>>> heating.
>
>> You're right, the amount of energy converted to heat is the same,
>> but by allowing the rim to cool for short periods, it won't reach as
>> high a peak temperature.
>
>With continuous braking the average temperature is reached, with
>pulsed braking, the peak temperature must be higher than the average
>because the same amount of energy must be dissipated in a shorter
>time. You cannot fool the energy equation. The best you can do is to
>allow the bike to roll as fast as is safe and dissipate more energy to
>wind drag and then use the brakes only when necessary. This will
>reduce peak temperatures.
>
>Jobst Brandt <jbr...@hpl.hp.com>
whatabout the cool down inbetween brake sequences ?
Doesnt that count ?
Thorsten
thorsten schaette
On 2 Feb 1998 19:38:12 GMT, jbr...@hpl.hp.com (Jobst Brandt) wrote:
>Mark Hickey writes:
>
>> Does it really matter in terms of total heat generation if you're
>> applying the brakes continuously or applying twice as much braking for
>> half the time? Unless I'm missing something very basic, the end
>> result is going to be the same in terms of tire and rim heating.
>
>Yes, you'll get twice the heat that must be removed by convection.
>
>Jobst Brandt <jbr...@hpl.hp.com>
with continous braking or "stutter" braking ?
Thorsten
thorsten schaette
YUP you are right on this one,
Although I still believe that this Tire blow stuff is highly 'blown
out of proportion '
Thorsten
thorsten schaette
On 1 Feb 1998 20:34:17 GMT, bro...@ele.tut.fi (Brodkin Panu) wrote:
: DONT !!!!
at least not yet ! :-)
>:
>--------------------------------------------------------------------
>Osoite: Panu Brodkin
Hello
please dont quote me out of context ! I said, that our disks dont
work as a drag brake on tandems ! Nothing else !
I said if you profesionaly race a DH Tandem ( I am sure there is at
least one or two ) You have to check after every run.
Every PRO checks the whole bike after every run, no matter what
brakes!
You said you had disks on your Tandem which are holding up .
Please tell me more, what disks , what tandem, what riding do you do,
how heavy are you and your stoker. Do you use the Tandem on long
descents fully loaded with 2 week gear, say for example in the Alps or
in the Rockies ?
Please let me know about your experiences!
Thanks Thorsten
P.S. and yes eventuall we will have a cross country disk, if that one
is working out for a Tandem , nobody knows at this moment. We will
have to make extensive tests before we sell it to Tandem users
William Herrera
On Tue, 3 Feb 1998 03:19:42, gor...@omegabbs.com (thorsten schaette)
wrote:
> please dont quote me out of context ! I said, that our disks dont
> work as a drag brake on tandems ! Nothing else !
> You said you had disks on your Tandem which are holding up .
> Please tell me more, what disks , what tandem, what riding do you do,
> how heavy are you and your stoker. Do you use the Tandem on long
> descents fully loaded with 2 week gear, say for example in the Alps or
> in the Rockies ?
I don't know the Alps, but I can tell you about disc brakes used to
drag downhill in the Rockies without problems.
Our tandem's disk brake (it's fairly old and I cannot read the small
triangular stamp of the brand on the body casting right now--if you
really care I can clean it with a rag and tell you later) has taken
quite a few such trips. Like the west to east trip over Trail Ridge
Road two years ago, although that is a rather straight road and does
not require serious braking except at the top (we did use the disc,
though it's sometimes fun passing cars on mountain roads).
I guess the best example I can think of was the trip from Creede to
Lake City in 1994. Slumgullion Pass drops from 11360 feet to 8600 feet
in about 10 miles (sorry I forget the exact mileage) into Lake City.
We were loaded with 2 rear panniers and one of those pop-up zipper
type center bags fully loaded. The downhill switchbacks had grit on
the pavement and could not be taken at faster than about 15 mph. We
had the drag disc brake fully on and we still had to use rim brakes
to keep it under 30 mph. Both the rims and the disk got somewhat hot
to the touch. No blowouts. The disk did not warp. Total weight with
both riders, bike and load was probably 360 lbs.
I also do not know whether blowouts are that big a risk except on
tandems. On a regular road bike I once completely wore out rather new
brake shoes on the descent from near the top of Mount Evans to Idaho
Springs (about a 6000 foot descent) without blowing out or warping the
(steel) rims.
Alan Walker
In article <6at1ei$h1q$1...@eskinews.eskimo.com>, sno...@eskimo.com says...
>
> I'm looking for ideas on how to increase our tandem stopping power.
Basically, all that energy has to be converted to heat, via friction. You
need something to dump the heat into, then a way to air cool it. I have
used a drum brake hub for 15 years, and I am quite happy with it. To some
extent, the heat can be dissipated through the spokes (12 gauge, in our
case). Even so, I once boiled a bidon's worth of water by slowly dribbling
it over a hot hub. (For any Aussies here, that was at the bottom of the
Corkscrew at Castambul)
I have no direct experience of disc brakes, but I am skeptical - something
with a greater mass is going to see a smaller temperature excursion.
Brodkin Panu
thorsten schaette (gor...@omegabbs.com) wrote:
: Hello
: please dont quote me out of context ! I said, that our disks dont
: work as a drag brake on tandems ! Nothing else !
Why they don't work ?!? Does the oil boil or what ??
: I said if you profesionaly race a DH Tandem ( I am sure there is at
: least one or two ) You have to check after every run.
: Every PRO checks the whole bike after every run, no matter what
: brakes!
OK. But how the absorbed energy depends on race vs. recretional use ?!?
: You said you had disks on your Tandem which are holding up .
: Please tell me more, what disks , what tandem, what riding do you do,
: how heavy are you and your stoker. Do you use the Tandem on long
: descents fully loaded with 2 week gear, say for example in the Alps or
: in the Rockies ?
: Please let me know about your experiences!
About the context ... I said that I have other than Magura disc brake.
(I did NOT say that I have tandems with disc brakes. - My wondering
is based on technical aspects ... And still I don't get it - what
fails if your brakes are used ??? Please tell me.)
: P.S. and yes eventuall we will have a cross country disk, if that one
I Hope that it would be affordable enought so see on production bikes.
: is working out for a Tandem , nobody knows at this moment. We will
: have to make extensive tests before we sell it to Tandem users
OK. I see the point in a view of R&D and durability testing.
Jobst Brandt
Thorsten Schaette writes:
> YUP you are right on this one, [about little weight transfer on
> tandems] although I still believe that this tire blow stuff is
> highly 'blown out of proportion '
You must not have descended a mountain road that is steeper than 8%
and curvy enough to limit speeds to no more than 20mph. In such a
descent, most of the potential energy is converted to heat in the rims
in the absence of a hub brake. Descending the Stelvio in Italy could
make you a quick believer. This is the road on which BMW, Mercedes,
Opel, FIAT, Ford, and Porsche test brakes. You should try it. It has
long sections of 10% with effectively a full stop at every hairpin.
Jobst Brandt <jbr...@hpl.hp.com>
Jobst Brandt
Thorsten Schaette writes:
> I said, that our disks don't work as a drag brake on tandems!
If the brake is any good it should work well as a supplementary brake.
I don't understand what makes the Magura not work in this capacity.
What is different about this brake that prevents it from converting
kinetic energy to heat?
Jobst Brandt <jbr...@hpl.hp.com>
Jobst Brandt
Thorsten Schaette writes:
>> With continuous braking the average temperature is reached, with
>> pulsed braking, the peak temperature must be higher than the
>> average because the same amount of energy must be dissipated in a
>> shorter time. You cannot fool the energy equation. The best you
>> can do is to allow the bike to roll as fast as is safe and
>> dissipate more energy to wind drag and then use the brakes only
>> when necessary. This will reduce peak temperatures.
> With continuous braking or "stutter" braking ?
As I said, pulsed braking does not change the net energy that must be
dissipated. In that respect, it might be worth noting that the rate
of heat transfer to the atmosphere is greatest at the highest
temperature. Therefore the hotter you can safely run the brake, the
smaller it can be to accomplish the task. Heat rejection by radiation
is not a factor at the temperatures achieved.
> What about the cool down between brake sequences? Doesn't that
> count?
Apparently you haven't tried this. When descending a mountain road,
whether cautiously and slowly or more rapidly, most of the energy must
go into the brake. The slow descent is the worst case because there
isn't much wind to cool the brake, while the faster descent, if below
about 20mph, still puts nearly all the energy into the brake.
On a typical curvy mountain road where no high speeds can be achieved
to create wind loss, braking is a necessity, and pumping the brake in
anything less than 10 second intervals has no effect on energy
dissipation although speed may get out of control. Pumping the brake
merely puts a ripple on the velocity profile with no significant
thermal effect.
Jobst Brandt <jbr...@hpl.hp.com>
Greg Franks
jbr...@hpl.hp.com (Jobst Brandt) writes:
Bill M. at Santana has found that many of the disk brakes that are
perfectly good for mountain bikes tend to self-destruct on tandems.
If I recall correctly, the rotors tend to warp from dumping too much
energy. Refer to the tandem mailing http://hobbes.ucsd.edu/tandem/
for more information.
--
__@ Greg Franks, (613) 520-5726 _~@ __O
_`\<,_ Systems Engineering, Carleton University, -^\<;^\<,
(*)/ (*) Ottawa, Ontario, Canada K1S 5B6. (*)%---/(*)
"Where do you want to go today?" Outside.
Hans-Joachim Zierke
Jobst Brandt schrieb:
> You must not have descended a mountain road that is steeper than 8%
> and curvy enough to limit speeds to no more than 20mph. In such a
> descent, most of the potential energy is converted to heat in the rims
> in the absence of a hub brake. Descending the Stelvio in Italy could
> make you a quick believer. This is the road on which BMW, Mercedes,
> Opel, FIAT, Ford, and Porsche test brakes.
It was the road where the first Torpedo hub prototypes were tested in 1902,
so the cyclists have been there quite early for their test runs.
At that time, I won't think of any asphalt.
hajo
Charles Maurer
In article <6b57t2$h...@hplntx.hpl.hp.com>, jbr...@hpl.hp.com (Jobst
Brandt) wrote:
> Charles Maurer writes:
>
> > In any case, strong rear brakes on a tandem are not very useful.
> > That's because at maximum deceleration of a tandem (ca. 0.8g, the
> > limit of tires), the rear wheel has virtually no load on it. All
> > the rear brakes do, really, is spell the front under light or
> > prolonged breaking.
>
> That's one of the features of tandems, that with their long wheelbase,
> load transfer is greatly reduced and rear wheel braking to control
> speed is reasonable and practical.
I don't think we're disagreeing. Rear braking to control speed is
reasonable and practical but merely controling speed does not require
strong rear brakes. Although load transfer is reduced, it is by no means
eliminated.
thorsten schaette
Hello,
I give up, to many experts. Its getting to theoretical !
Let me however say this :
I will not sell our current Downhill Disc (GustavM) to a Tandem user
here in 'my' USA market. And I think the German Magura Guys wouldnt do
it either in Europe.
Before somebody now says : Yeah easy to say ,,,its too expensive
anyhow.............. I had a lot of seemingly knowing people asking me
for quotes for discs on their Tandems.
Tandems are different, way different ! And a rehashed MTB brake
doesn't cut it. No matter what brand !
My personal favourite are Magura Rim brakes either Drop Handles or MTB
Levers front and rear. For touring in the Rockies or Alps or similar
areas I would add an old Arai drum brake to the equation. Current
design Disk brakes I would not use !
At least not at the moment.
Now, what I like to see in a Tandem Disc.
Vented rotors, with big enough vents to channel enough air through
( not crossdrilled or slotted but VENTED )
Stainless Steel rotors
double floating piston, (on one side, in order to have the least
spoke dish , just like our current brake )
the little hissing sound, this design makes, I wouldnt mind !
Fully hydraulic with large enough expansion chamber ( again, just like
our current Disc )
the use of enviromental friendly ( or at least not harmful ) fluid .
( also the same as current )
Why you say, dont you make one ?
Easy !
The bracket needs to be widened,
the caliper needs to be wider,
the disk would be very difficult ( expensive !! ) to make
for how many bikes ( Tandems ) ? 5000 per year ?
Please remember , that the current Tandem frames need to be
substantially reinforced, etc. My guess, the tandem which would need
such a brake would cost in excess of 5000 $ .
Again how many brakes would I sell ? 5000 sets ? I dont believe so.
Let me know what you think, I am here to listen .
Thanks Thorsten
evans-the-swim
Sheldon Brown <Capt...@sheldonbrown.com> wrote:
>No, it doesn't. The cooling, by radiation and conduction, occurrs
>continuously as long as the rim is hotter than the ambient air, whether
>the brake is being applied or not.
>Sheldon "Studied Physics In High School, Still Remembers Some" Brown
>Newtonville, Massachusetts
Heat flow is proportional to the temperature difference, and so
there's no doubt a hysterisis loop that suggests that intermittent
braking should allow less heat to radiate. However, there are two
other considerations, one also analytical, the other practical.
The mechanism by which tyres blow must have some time-component - the
rubber creeps, or gets softer, or both; and as well the transfer from
the rim to the tyres must lag that from the pads to the rims.
Using an intermittent braking technique can thus allow faster average
speeds even in an all-else-being-equal scenario. What you do is keep
the peak heat generation short enough in time to avoid permanant
reduction in the attachment of the tyre to the rim.
The practical advantage is that if a tyre does blow, it'll most likely
do so when the rim is hottest, at the end of your braking section,
when you are going the slowest. For this reason, if in survival mode,
do the bulk of your braking (well) before the turns.
Hans-Joachim Zierke
thorsten schaette schrieb:
> Tandems are different, way different ! And a rehashed MTB brake
> doesn't cut it. No matter what brand !
I think you got something wrong.
Scenario: Magura Germany writes: "Diese Bremse ist für Tandems zugelassen."
If they do this, tandem riders will assume, that a pair of Gustav Ms is
sufficient to stop a tandem.
Even in Germany, where we don't have ambulance chasers and such, Magura
will get into problems with lawyers then.
This is not my assumption, nor the assumption of other participants in this
newsgroup. We know that we can widen your logic to:
"No current bicycle brake is enough to stop a tandem." In the normal
bicycle setup, one brake front, one brake rear, this is true under hilly
conditions. (It is not true for MY tandem due to its enormous air drag, but
that's another story.)
That's why tandems are delivered with three brakes, and I do not see any
reason why the Gustav M should not work fine as a drag brake. Remember: The
drag brake is not the brake that stops the tandem. Two Magura rim brakes,
preferably on Magura braze-ons instead of that funny cantilever studs, and
a Gustav M as a drag brake will work.
> Why you say, dont you make one ?
> Easy !
> The bracket needs to be widened,
> the caliper needs to be wider,
> the disk would be very difficult ( expensive !! ) to make
Too much tooling costs, we can never buy that. Instead, deliver tandem
brake levers that allow one Gustav M and one rim brake connected to one
lever. All you have to do, is a different diameter for pressing that oil.
This is the charme of hydraulics, you forgot to USE the advantages that
your technology brings to the user, ERR could bring to the user.
Keep it simple, stupid! ;-)
hajo
Matt Castelein
Jobst Brandt wrote:
> With continuous braking the average temperature is reached, with
> pulsed braking, the peak temperature must be higher than the average
> because the same amount of energy must be dissipated in a shorter
> time. You cannot fool the energy equation. The best you can do is to
> allow the bike to roll as fast as is safe and dissipate more energy to
> wind drag and then use the brakes only when necessary. This will
> reduce peak temperatures.
Yeah, or you could just get Hayes disc brakes and not worry about it.
They have solved the heat/expansion/drag problem quite niceley.
--
Purgamentum init, exit purgamentum.
- Matt Castelein - System Operator -
-=Cold Fusion Online, Rochester NY=-
Web- http://www2.rpa.net/~night1/sysop.html
Jobst Brandt
Thorsten Schaette writes:
> I give up, too many experts. Its getting too theoretical!
I don't know to what this is a response but I thought you were a
representative of Magura brakes and you clearly made a series of
provocative technical statements. I think you are confusing the word
"theoretical" with "technical".
> I will not sell our current Downhill Disc (GustavM) to a Tandem user
> here in 'my' USA market. And I think the German Magura Guys wouldn't do
> it either in Europe.
You must have reasons for this and that certainly isn't TOP SECRET, so
how about telling us what it is that makes your brake inappropriate
for use on various bicycles.
> Tandems are different, way different! And a rehashed MTB brake
> doesn't cut it. No matter what brand!
What do you mean by "rehashed MTB brake"? As I see it, a brake is a
brake and should perform on a bicycle. That a 200lb rider on a MTB
using only one brake can achieve the same braking limits that a tandem
can is also apparent. So where is the problem?
> My personal favourite are Magura Rim brakes either Drop Handles or
> MTB Levers front and rear. For touring in the Rockies or Alps or
> similar areas I would add an old Arai drum brake to the equation.
> Current design Disk brakes I would not use! At least not at the
> moment.
Why? And, what is wrong with "the moment"? Is there something else
we don;t know about these brakes that we should know? Other disk
brake manufacturers don't put such restrictions on their brakes, so
what is different about Magura?
> Now, what I like to see in a Tandem Disc. Vented rotors, with big
> enough vents to channel enough air through (<not cross-drilled or
> slotted but VENTED) Stainless Steel rotors
What do you mean by "vented" if it's not holes in the disk? Are you
suggesting cast disks with pump impeller type internal channels? This
is getting stranger all the time. Bicycle disks do not turn fast
enough to make centrifugal pumping effective and the weight of a cast
disk makes it useless. Stainless steel is such a poor thermal
conductor that it would make a horrible brake, the surface
temperatures rising to brake fade levels immediately.
> double floating piston, (on one side, in order to have the least
> spoke dish , just like our current brake) the little hissing sound,
> this design makes, I wouldn't mind!
Maybe you ought to look at some motorcycle brakes instead of designing
an unworkable brake here on the net. What's this hissing sound you
speak of?
The exclamation mark "!" is usually used for emphasis. You have an
awful lot of emphasis on technical aspects, for one who has just said:
"I give up, too many experts. Its getting too theoretical!"
Jobst Brandt <jbr...@hpl.hp.com>
Jobst Brandt
Evans (who?) writes:
> Heat flow is proportional to the temperature difference, and so
> there's no doubt a hysterisis loop that suggests that intermittent
> braking should allow less heat to radiate. However, there are two
> other considerations, one also analytical, the other practical.
If you are going to give a physics refresher you might note that "heat
flow" is redundant, heat being thermal energy in transit. Besides,
radiant heating and cooling is proportional to the fourth power of the
temperature difference of the source and sink, the emissivities and
the Boltzmann constant. Therefore, radiation plays an insignificant
part in cooling leaving the task to convection.
> The mechanism by which tyres blow must have some time-component -
> the rubber creeps, or gets softer, or both; and as well the transfer
> from the rim to the tyres must lag that from the pads to the rims.
> [...]
> The practical advantage is that if a tyre does blow, it'll most
> likely do so when the rim is hottest, at the end of your braking
> section, when you are going the slowest. For this reason, if in
> survival mode, do the bulk of your braking (well) before the turns.
That's a lot of theorizing. Those who have had this occur can tell
you that such tires at times blow out when no braking is taking place.
It has a lot to do with pressure as well as the temperature at the rim
contact with the bead.
Jobst Brandt <jbr...@hpl.hp.com>
Scott Seligman
jbr...@hpl.hp.com (Jobst Brandt) writes:
>
> With continuous braking the average temperature is reached, with
> pulsed braking, the peak temperature must be higher than the average
This is clearly true. Assuming that you brake for one second on, say,
and one second off, will the peak temperature be much higher than the
average? Enough to make a noticeable difference?
Scott Seligman
thorsten schaette
On Wed, 04 Feb 1998 11:28:58 -0500, Matt Castelein <nig...@rpa.net>
wrote:
>Jobst Brandt wrote:
>
>> With continuous braking the average temperature is reached, with
>> pulsed braking, the peak temperature must be higher than the average
>> because the same amount of energy must be dissipated in a shorter
>> time. You cannot fool the energy equation. The best you can do is to
>> allow the bike to roll as fast as is safe and dissipate more energy to
>> wind drag and then use the brakes only when necessary. This will
>> reduce peak temperatures.
>
>Yeah, or you could just get Hayes disc brakes and not worry about it.
>They have solved the heat/expansion/drag problem quite niceley.
>
And how is that ?? In their advertising or in the real world ??
Thorsten
thorsten schaette
>representative of Magura brakes and you clearly made a series of
>provocative technical statements. I think you are confusing the word
>"theoretical" with "technical".
Can I not be provocative??? ( by the way " " " " ??????????)
>> I will not sell our current Downhill Disc (GustavM) to a Tandem user
>> here in 'my' USA market.
>how about telling us what it is that makes your brake inappropriate
>for use on various bicycles.
particular the use of current available Disc brakes as Drag brakes.
And no, the reasons why I wont sell a GustavM to a Touring Tandem are
not top secret .
>> doesn't cut it. No matter what brand!
just beef it up a little and than it should perform on a Tandem.
I love Tandem's and most people, who ride them. So I think a Tandem
component should be specifically designed for a Tandem.
>brake and should perform on a bicycle. That a 200lb rider on a MTB
>using only one brake can achieve the same braking limits that a tandem
>can is also apparent. So where is the problem?
by two persons. The weight and the wheelbase of the whole setup makes
it possible that the wheels do not lock up as easy as with a single
bike. Therefore the friction on the brakes would reach much higher
temperaturs. Compared to a Mtb Wheel which would lock up much easier
>> My personal favourite are Magura Rim brakes either Drop Handles or
>> MTB Levers front and rear. For touring in the Rockies or Alps or
>> similar areas I would add an old Arai drum brake to the equation.
>> Current design Disk brakes I would not use! At least not at the
>> moment.
>Why? And, what is wrong with "the moment"? Is there something else
>we don;t know about these brakes that we should know? Other disk
>brake manufacturers don't put such restrictions on their brakes, so
>what is different about Magura?
everything is different about Magura. While other Manufacturers
seemingly let people buy everything they make, we limit ourselves to
the uses, which we think is apropiate for that product. We are in for
the long haul and want satiesfied long term customers, instead of the
fast buck.
And yes there just might be something different, but that is top
secret. :-)
>> Now, what I like to see in a Tandem Disc. Vented rotors, with big
>> enough vents to channel enough air through (<not cross-drilled or
>> slotted but VENTED) Stainless Steel rotorsStainless steel is such a poor thermal
>conductor that it would make a horrible brake, the surface
>temperatures rising to brake fade levels immediately.
Ha ! Got you ! What material do the other Disc Guys use for their
rotors, .......... stainless Steel !
But you are right, a vented cast disk would be very heavy and not
very useful because of slow speeds.
>> double floating piston, (on one side, in order to have the least
>> spoke dish , just like our current brake) the little hissing sound,
>> this design makes, I wouldn't mind!
>Maybe you ought to look at some motorcycle brakes instead of designing
>an unworkable brake here on the net. What's this hissing sound you
unworkable......... motorcycle brakes , what do you mean ?
>The exclamation mark "!" is usually used for emphasis. You have an
>awful lot of emphasis on technical aspects, for one who has just said:
>"I give up, too many experts. Its getting too theoretical!"
That is typical German . You have to play Teacher , dont you !
Everbody knows that you have an attitude, some people might even hate
you, I take it, being a German myself . And again, I am here to learn
and listen. I am not here to get flammed, not even from you !
Thorsten
>Jobst Brandt <jbr...@hpl.hp.com>
Happy Trails
Now please dont tell me to write all the words small , or that i have
forgotten some ,,,,,,,,,,, here and there.
;-)
Jobst Brandt
Scott Seligman writes:
>> With continuous braking the average temperature is reached, with
>> pulsed braking, the peak temperature must be higher than the
>> average.
> This is clearly true. Assuming that you brake for one second on,
> say, and one second off, will the peak temperature be much higher
> than the average? Enough to make a noticeable difference?
The point is that pumping the brakes is: 1. Only possible if you are
traveling at a trivial rate on a trivial slope. 2. It does not
achieve what its proponents claim anyway. It is a theoretical
proposal that appeals to the hypothetical rider. It isn't there and
it doesn't do any good.
Jobst Brandt <jbr...@hpl.hp.com>
but...@apollo.hp.com
Thorsten Schaette writes:
> Now, what I like to see in a Tandem Disc. Vented rotors, with big
> enough vents to channel enough air through (<not cross-drilled or
> slotted but VENTED) Stainless Steel rotors
Does that mean that the cross drilled rotors on my motorcycle aren't
sufficient? They seem to work ok, despite the 700 lb loaded weight and
speeds up to 165 mph.
--
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=
Tim Butler Massachusetts Language Lab - Hewlett Packard
email: but...@apollo.hp.com
Hans-Joachim Zierke
Matt Castelein schrieb:
> Yeah, or you could just get Hayes disc brakes and not worry about it.
> They have solved the heat/expansion/drag problem quite niceley.
And how did they do this?
hajo
Matt Castelein
They used an open hydraulic system; one with an expansion chamber to
take up the fluid expansion from the heat. They've got a few other
tricks too. Why don't you talk to them yourself? 1.800.686.3472
Hans-Joachim Zierke
Matt Castelein schrieb:
> They used an open hydraulic system; one with an expansion chamber to
> take up the fluid expansion from the heat.
Oh well, the Magura uses an expansion chamber as well. This does not change
the fact that heat transfer by the disk has some limits.
> They've got a few other
> tricks too. Why don't you talk to them yourself? 1.800.686.3472
First, you do not post to a local newsgroup, and 1-800 does not work here.
Second, "a few other tricks" sounds like somebody who is a fan of an item,
but does not know why.
hajo
Matt Castelein
Hans-Joachim Zierke wrote:
> First, you do not post to a local newsgroup, and 1-800 does not work here.
> Second, "a few other tricks" sounds like somebody who is a fan of an item,
> but does not know why.
>
> hajo
Sorry, forgot about the 1-800.. I don't have another number, but here's
the address:
Hayes Brake, Inc.
5800 W. Donges Bay Rd.
Mequon, WI 53092 USA
And about that other bit, I simply was too tired to post all the info
they
gave me. thats why I gave the number. I'm not what I'd call a fan, I
just
think their setup looks pretty sharp to me. some of the other 'tricks'
include:
lightweight disk that resists warping better*
non-organic pads+
(* This is their claim, I have not tested it myself)
(+ same material as harley davidson motorcycles)
This is all just for information only. I'm not trying to prove a point
or sell this product, I'm just encouraging everyone else to check it
out for themselves.
thorsten schaette
On Sun, 08 Feb 1998 03:28:39 -0500, Matt Castelein <nig...@rpa.net>
wrote:
>Hans-Joachim Zierke wrote:
>
>> First, you do not post to a local newsgroup, and 1-800 does not work here.
>> Second, "a few other tricks" sounds like somebody who is a fan of an item,
>> but does not know why.
>>
>> hajo
>
>Sorry, forgot about the 1-800.. I don't have another number, but here's
>the address:
>
>Hayes Brake, Inc.
>5800 W. Donges Bay Rd.
>Mequon, WI 53092 USA
>
>And about that other bit, I simply was too tired to post all the info
>they
>gave me. thats why I gave the number. I'm not what I'd call a fan, I
>just
>think their setup looks pretty sharp to me. some of the other 'tricks'
>include:
>
>lightweight disk that resists warping better*
>non-organic pads+
>
>(* This is their claim, I have not tested it myself)
>(+ same material as harley davidson motorcycles)
>
>This is all just for information only. I'm not trying to prove a point
>or sell this product, I'm just encouraging everyone else to check it
>out for themselves.
Hi Matt
no heat problem because of heat expansion reservoir. Yup, that works !
But how big is that reservoir ? Is it big enough to allow all the
fluid to expand , when the going gets tough ?? What works for mild
cross country might not be enough for a real downhill !
Why is Hayes using enviromental harmfull dot brake fluid ? Sure not
because they have no heat expansion problem. You write about warping
discs, better than whom's discs ???
You are not a fan but have the 800 Number and full adress ready on
hand ?
Than this old Harley thingy. Can you find anybody on this planet who
tells you that Harley brakes are any good ??? Or can you find actually
hundreds of brake people who manufacture Harley replacement brakes .
And what brakes is every Harley Racer using ( if it is allowed by the
racing authorities to change the brakes ) Hayes ???
Just that you know, I am working for Magura, and have no qualms
telling everybody. Actually I am proud of the fact.
3 times consecutive Worldchampion, 1,2 pro Men 1,2,4 Pro Women USA
Downhill Championships, Silver in the DH Worlds ( 2 consecutive times
also ) gives Hayes a little to catch up to. And I am sure they are
trying !
Thorsten
am i biased ? YUP you bet I am !
Hans-Joachim Zierke
Matt Castelein schrieb:
> lightweight disk that resists warping better*
> non-organic pads+
>
> (* This is their claim, I have not tested it myself)
> (+ same material as harley davidson motorcycles)
AFAIK, all bicycle diskbrakes use pads of the suppliers to car or
motorcycle manufacturers.
In practical use, this can bring problems, because some brake behaviour is
fine with a heavy vehicle, and quite a problem with a bicycle. For example,
the Sachs Aluminum disc has a very sharp transition from wet braking to
no-longer-wet braking. You won't feel this with a fast heavy vehicle,
because it would happen during the first tenth of seconds, but is a severe
problem for bicycle use.
The brakepad manufacturer also makes the Porsche brakepads, but this does
not tell us a lot. It is just good for marketing.
hajo
--
Waiting for uucp-i/2
Hans-Joachim Zierke
thorsten schaette schrieb:
( 50 lines of quoting... :-( )
> Or can you find actually
> hundreds of brake people who manufacture Harley replacement brakes .
:-) Not bad an argument...
> 3 times consecutive Worldchampion, 1,2 pro Men 1,2,4 Pro Women USA
> Downhill Championships, Silver in the DH Worlds ( 2 consecutive times
> also )
This is less good an argument. I do not care about sponsorship at all.
Measured by sponsored winners in road races, Suntour or Sachs parts were
hardly usable, but I know better.
How much of your marketing money is put into sponsorship?
hajo
Matt Castelein
thorsten schaette wrote:
> no heat problem because of heat expansion reservoir. Yup, that works !
> But how big is that reservoir ? Is it big enough to allow all the
> fluid to expand , when the going gets tough ?? What works for mild
> cross country might not be enough for a real downhill !
They are, acording to hayes, made first and foremost for DH.
And I'm sorry, but I haven't had a chance to measure one!
> Why is Hayes using enviromental harmfull dot brake fluid ? Sure not
> because they have no heat expansion problem.
I don't know, what does everyone else use?
> You write about warping
> discs, better than whom's discs ???
Better than average.
> You are not a fan but have the 800 Number and full adress ready on
> hand ?
I have a publication that lists them.
> Than this old Harley thingy. Can you find anybody on this planet who
> tells you that Harley brakes are any good ???
I bet I could, if I cared enough to want to go searching.
> Or can you find actually
> hundreds of brake people who manufacture Harley replacement brakes .
I think I could find hundreds of people who manufacture replacement
ANYTHING, harley or otherwise. Thats a bit silly..
> And what brakes is every Harley Racer using ( if it is allowed by the
> racing authorities to change the brakes ) Hayes ???
I have absolutley no idea. I told you FOR INFORMATION ONLY. You
seem to need more information than I can provide. Perhaps you
should contact Hayes yourself and talk to them? Oh look, theres
the number!
> Just that you know, I am working for Magura, and have no qualms
> telling everybody. Actually I am proud of the fact.
Congratulations.
> 3 times consecutive Worldchampion, 1,2 pro Men 1,2,4 Pro Women USA
> Downhill Championships, Silver in the DH Worlds ( 2 consecutive times
> also ) gives Hayes a little to catch up to. And I am sure they are
> trying !
And I'm sure you will always be right there, ready with your company
propaganda in hand. Lay off me, will ya!?!
> am i biased ? YUP you bet I am !
I wish I HAD bet, I'd be a rich man.
Brodkin Panu
thorsten schaette (gor...@omegabbs.com) wrote:
: no heat problem because of heat expansion reservoir. Yup, that works !
I think that the boiling is still a problem. With expansion reservoir
You'll lose all braking power when the fluid boils .... No good ...
: But how big is that reservoir ? Is it big enough to allow all the
: fluid to expand , when the going gets tough ?? What works for mild
: cross country might not be enough for a real downhill !
Does the mineral oil used in Maguras expand so much (tens percents) ??
: Why is Hayes using enviromental harmfull dot brake fluid ? Sure not
Why should the fluid leak to the ground ?? (Does Your leak ?)
: because they have no heat expansion problem. You write about warping
Maybe they do not have such expansion problem because of the use of
brake fluids - I'll bet there is a reason for calling it the brake
fluid ..
: discs, better than whom's discs ???
Formulas (Paiolis) discs are similar to motorbike discs (especially
the flotating mounting) - I'll bet again that the motorbike construktion
has the reasons ...
: Just that you know, I am working for Magura
Then You should have some technical facts and arguments for
choosing the construktion !!
: Thorsten
: am i biased ? YUP you bet I am !
I'm sure that You are !! Still I think that automotive and
motorcycle manufacturers have solved this problem allready.
--
--------------------------------------------------------------------
Osoite: Panu Brodkin "Erehtyyhän sitä -
Insinöörinkatu 60D247 Useimmiten !!"
33720 Tampere
Email: Panu.B...@cc.tut.fi
--------------------------------------------------------------------
Tim Heinemann
>Why is Hayes using enviromental harmfull dot brake fluid ? Sure not
>because they have no heat expansion problem. You write about warping
>discs, better than whom's discs ???
How much does Magura´s oil expand under heat compared to DOT3 or 4?
>Than this old Harley thingy. Can you find anybody on this planet who
>tells you that Harley brakes are any good ??? Or can you find actually
>hundreds of brake people who manufacture Harley replacement brakes .
They are actually not much better: You can buy showchromed dics from
some of them........................
>And what brakes is every Harley Racer using ( if it is allowed by the
>racing authorities to change the brakes ) Hayes ???
Brembo
Matt O'Toole
In article <6bo6rh$8...@hplntx.hpl.hp.com>, jbr...@hpl.hp.com says...
> Two things can be done to prevent this, the first is to insulate the
> piston from the brake pad, the second is to use automotive brake fluid
> of which huge quantities are available in the industry.
This is true, but anyone who's ever had brake fluid on his hands knows
how nasty it is. The plain oil used in bicycle suspensions should work
fine, and it's a lot less messy and nasty to deal with. It's also
already being used in bike shops. Brake fluid is used in cars to keep
water from collecting into droplets that cause corrosion. I'm not so
sure water intrusion is such a problem in bicycle brakes.
> As a
> secondary improvement, disks should not be made of stainless steel
> because it has such a poor thermal conductivity that unnecessarily
> high surface temperatures are readily achieved. This in turn
> overheats the pads and ultimately the brake fluid.
Yes, indeed.
I vote for Alumninum MMC as a disk material. It has excellent thermal
conductivity, light weight, good hardness, and is fully "buzzword
compliant."
> I think it is embarrassing how little you understand about the brakes
> and expound on it with such certainty. You are not doing Magura any
> favors.
Don't be so hard on the guy, Jobst. At least he's making an effort,
which is more than I can say about reps from other companies, who are
afraid to show themselves here. Yes, the technical ignorance is
disguting, but you should know that it's par for the course in an
industry run by ex-jocks-turned-sales-managers. If they're all afraid to
come out and be "corrected" by the likes of yourself, no one will ever
learn anything!
Matt O.
Jobst Brandt
Thorsten Schaette writes:
> No heat problem because of heat expansion reservoir. Yup, that
> works! But how big is that reservoir? Is it big enough to allow
> all the fluid to expand , when the going gets tough?? What works
> for mild cross country might not be enough for a real downhill!
I think you have your science backwards. Expansion of fluid is not
the problem for hydraulic brakes but rather the vaporization. This is
not resolved with expansion chambers or any other such volume because
the gas is generated in the receiving cylinder and it is compressible.
No doubt, fluid being pushed back into the transmitting (hand lever)
cylinder by generated gas causes fluid to emerge from the reservoir,
but this has only a secondary relevance, the gas in the actuator
cylinder being the brake debilitating cause.
Two things can be done to prevent this, the first is to insulate the
piston from the brake pad, the second is to use automotive brake fluid
of which huge quantities are available in the industry. As a
secondary improvement, disks should not be made of stainless steel
because it has such a poor thermal conductivity that unnecessarily
high surface temperatures are readily achieved. This in turn
overheats the pads and ultimately the brake fluid.
> Why is Hayes using enviromental harmfull dot brake fluid ? Sure not
> because they have no heat expansion problem. You write about warping
> discs, better than whom's discs ???
If you used water as a brake fluid it would be even more
environmentally friendly but alas, automotive brake fluid is designed
for this purpose and it works. The pittance of fluid used by bicycles
is like a drop of salt water in the soup, it cannot be detected. Just
the oil dropped from cars in one hour of commute traffic on one mile
of freeway makes all the oil dropped by all bicycles in a year
insignificant.
> Just that you know, I am working for Magura, and have no qualms
> telling everybody. Actually I am proud of the fact.
I think it is embarrassing how little you understand about the brakes
and expound on it with such certainty. You are not doing Magura any
favors.
> 3 times consecutive Worldchampion, 1,2 pro Men 1,2,4 Pro Women USA
> Downhill Championships, Silver in the DH Worlds ( 2 consecutive times
> also ) gives Hayes a little to catch up to. And I am sure they are
> trying !
So? That's a bunch of advertising hype. World champions rode
Campagnolo Delta brakes as well and they were one of the worst caliper
brakes ever made. I don't get much from sponsorship advertising
because it has little relation with what works well. Some sponsored
equipment is renewed for each event because it is so unreliable.
Jobst Brandt <jbr...@hpl.hp.com>
thorsten schaette
>>no heat problem because of heat expansion reservoir. Yup, that works !
>> But how big is that reservoir ? Is it big enough to allow all the
>> fluid to expand , when the going gets tough ?? What works for mild
>> cross country might not be enough for a real downhill !
>They are, acording to hayes, made first and foremost for DH.
>And I'm sorry, but I haven't had a chance to measure one!
Why are so few people using them for DH ? And yes please try out a set
I will be glad to borrow you my bike ( or better , check the Parktool
workstation at one of the races, and borrow a Bike with our ( Magura)
brakes on it. than compare .
>> Why is Hayes using enviromental harmfull dot brake fluid ? Sure not
>> because they have no heat expansion problem.
who told you that Hayes has no expansion problem?
Hayes (Hope, and most the others ) are using DOT because of the heat.
DOT brake fluid is better to dissipate the heat and doesnt expand as
much . BUT it is enviromentally harmful and if you spill something,
while you work on the brakes ( and you will ! ) you ruin your
paintjob.
>I don't know, what does everyone else use?
we use mineral oil, shock oil, ready available, you can even use
cooking oil. all the oil we use is enviromental friendly.
>> You write about warping
>> discs, better than whom's discs ???
>Better than average.
Average ! Please tell us, what discs you have tested, or where you
find an average . Than if one of our discs warps, send it it and get
warranty replacement ! How about that ?
>> Than this old Harley thingy. Can you find anybody on this planet who
>> tells you that Harley brakes are any good ???
>I bet I could, if I cared enough to want to go searching.
I am sure you will( might take you a little while though ) , but
believe me, although Harleys are nice, the brakes are not a strong
point. On BMW motorcycles however, the brakes are mated to the
performance and generally getting praises .
And although I dont want to make this a huge own advertising, : BMW's
Motorcycles have Magura Brakes on it.
>> Or can you find actually
>> hundreds of brake people who manufacture Harley replacement brakes .
I dont know of anybody who makes aftermarket brakes for BMW. There is
simply no need to improve on an excellent brake.
>I think I could find hundreds of people who manufacture replacement
>ANYTHING, harley or otherwise. Thats a bit silly..
Nope, if there is no need to improove something, than there will be
very little activity in this marketsegment.
>> And what brakes is every Harley Racer using ( if it is allowed by the
>> racing authorities to change the brakes ) Hayes ???
Lets say most racers are using Magura Mastercylinder, some also use
Performance Machine.
>I have absolutley no idea. I told you FOR INFORMATION ONLY. You
>seem to need more information than I can provide. Perhaps you
>should contact Hayes yourself and talk to them? Oh look, theres
>the number!
I know. But again. I was trying to ask questions, instead of simply
touting our own horn.
> 3 times consecutive Worldchampion, 1,2 pro Men 1,2,4 Pro Women USA
>> Downhill Championships, Silver in the DH Worlds ...
see, thats what I mean, I dont want to sound obnoxious Of course I
believe in our own stuff. The DH results across the world are facts,
NOT advertising.
>And I'm sure you will always be right there, ready with your company
>propaganda in hand. Lay off me, will ya!?!
I didnt start to praise Magura. It was you, who knew so much about
hayes. It sounded like their ads.
Please Matt, I dont want to sound agressive, I just think if somebody
makes pretty big claims, that he should have the possibility to back
them up. And I apologize , if I have hurt your feelings, it is not my
intention. Now instead of 'fightin' lets dust off the old bike and go
for a little ride. If you have any questions please email me and I
will try to answer them. And please, take my advice, try booth brakes
out, and you might even like the hayes better, than go for it !
Happy Trails
Thorsten
thorsten schaette
On 9 Feb 1998 16:39:19 GMT, bro...@ele.tut.fi (Brodkin Panu) wrote:
>thorsten schaette (gor...@omegabbs.com) wrote:
>
>: no heat problem because of heat expansion reservoir. Yup, that works !
>I think that the boiling is still a problem. With expansion reservoir
>You'll lose all braking power when the fluid boils .... No good ...
You are right. But less fluid boils easier !
>: But how big is that reservoir ? Is it big enough to allow all the
>: fluid to expand , when the going gets tough ?? What works for mild
>: cross country might not be enough for a real downhill !
>Does the mineral oil used in Maguras expand so much (tens percents) ??
yup it does, thats why we have a huge ( comparable) reservoir
>: Why is Hayes using enviromental harmfull dot brake fluid ? Sure not
>Why should the fluid leak to the ground ?? (Does Your leak ?)
nope WE dont leak, and even if , than we have a great warranty against
that. ( 2 years !)
>: because they have no heat expansion problem. You write about warping
>Maybe they do not have such expansion problem because of the use of
>brake fluids - I'll bet there is a reason for calling it the brake
>fluid .
Everybody has a heat expansion problem, there are just more or better
ways to solve the problem.
>: discs, better than whom's discs ???
>Formulas (Paiolis) discs are similar to motorbike discs (especially
>the flotating mounting) - I'll bet again that the motorbike construktion
>has the reasons ...
Ours are much more like a motorcycle, Our piston floats and has two
pistons on one side, just like car or motorcycle brakes. Yes there are
some Motorcycles with floating disks ( like formulas ) but very few.
>: Just that you know, I am working for Magura
>Then You should have some technical facts and arguments for
>choosing the construktion !!
We sure do, and I am happy to discuss this further.
just email me and we can 'talk' .
I am also more than happy to send you some technical information,
which might explain a few things better, than i can, typing this late
in the evening. : -)
>I'm sure that You are !! Still I think that automotive and
>motorcycle manufacturers have solved this problem allready.
Kind of ! But bicycle discs are a different kind of animal all
together.
>
The reason I was asking questions instead of getting nasty about big
advertising slogans, was simply, that I didnt want to blow my own
horn. Now I have ! And I am sorry about this !
I dont want to make anybody feeling less apreciated, but I also want
facts instead of advertising.
I hope I didnt offend you in any way, if I did, please accept my
apologies.
Happy Trails
Thorsten
Hans-Joachim Zierke
Matt O'Toole schrieb:
> This is true, but anyone who's ever had brake fluid on his hands knows
> how nasty it is. The plain oil used in bicycle suspensions should work
> fine, and it's a lot less messy and nasty to deal with. It's also
> already being used in bike shops. Brake fluid is used in cars to keep
> water from collecting into droplets that cause corrosion. I'm not so
> sure water intrusion is such a problem in bicycle brakes.
The Magura rim brakes are one of the most reliable items in bicycle
history, I have been very sceptical in the beginning, but it was proven by
10 years of use by xthousands of commuters.
And since I have worked with the stuff lots of times, I know how easy it is
to spill a little oil when bleeding at the handlebar leaver.
If there is need for "real" brake fluid for extreme conditions like tandem
use, its use should be limited to these conditions.
> I vote for Alumninum MMC as a disk material. It has excellent thermal
> conductivity, light weight, good hardness, and is fully "buzzword
> compliant."
My problem with aluminum disks has been, that the transition from wet
braking to no-longer-wet braking was so sharp, that I got rid of them in
favour of steel disks.
hajo
Hans-Joachim Zierke
Jobst Brandt schrieb:
> As a
> secondary improvement, disks should not be made of stainless steel
> because it has such a poor thermal conductivity that unnecessarily
> high surface temperatures are readily achieved.
Is plated "normal" steel any better?
hajo
Jobst Brandt
Matt O'Toole writes:
>> Two things can be done to prevent this, the first is to insulate
>> the piston from the brake pad, the second is to use automotive
>> brake fluid of which huge quantities are available in the industry.
> This is true, but anyone who's ever had brake fluid on his hands
> knows how nasty it is. The plain oil used in bicycle suspensions
> should work fine, and it's a lot less messy and nasty to deal with.
> It's also already being used in bike shops. Brake fluid is used in
> cars to keep water from collecting into droplets that cause
> corrosion. I'm not so sure water intrusion is such a problem in
> bicycle brakes.
Water intrusion is a major problem because it makes steam. Steam is a
compressible fluid and renders the brakes useless even before a poorly
formulated fluid will vaporize. Corrosion is a secondary problem.
Less apparent is that brake fluid is hygroscopic and for this reason
master cylinders on cars are sealed from the atmosphere by a rubber
bellows expansion element to allow for reduced reservoir fluid due to
brake pad wear.
> I vote for Aluminum MMC as a disk material. It has excellent
> thermal conductivity, light weight, good hardness, and is fully
> "buzzword compliant."
Of what is MMC a matrix? Aluminum works if it is hard anodized,
however, anodizing is an insulator that causes high surface
temperatures as we see on anodized rims. An aluminum disk with a
metal-spray steel coating would be better but expensive.
>> I think it is embarrassing how little you understand about the
>> brakes and expound on it with such certainty. You are not doing
>> Magura any favors.
> Don't be so hard on the guy, Jobst. At least he's making an effort,
> which is more than I can say about reps from other companies, who are
> afraid to show themselves here.
There is a difference between making an effort and blustering
erroneous information as fact under the guise of inside information
from the manufacturer. That is what raises my concern and as you may
have noticed, it is this type of posting that draws my fire.
Netiquette lets us overlook typos or inadvertent proof reading
failures, but does not mean we must suffer in silence those who cannot
format their responses and learn to spell. This is not unfamiliarity
with the language because Torsten's post are equally disjointed when
he posts on the German net rec.fahrrad.de! or was it !!!
Jobst Brandt <jbr...@hpl.hp.com>
Jobst Brandt
Hajo writes:
> The Magura rim brakes are one of the most reliable items in bicycle
> history, I was sceptical in the beginning, but ten years of
> commuting on thousands of trips convinced me.
I think we are mixing subjects here. The brake fluid for disks is
subjected to higher temperatures than rim brakes. This was also true
for automobile drum brakes at the advent of disks. New brake fluid
had to be formulated.
> If there is need for "real" brake fluid for extreme conditions like
> tandem use, its use should be limited to these conditions.
It's not the tandem but the disk brake that requires better brake
fluid.
Jobst Brandt <jbr...@hpl.hp.com>
Jobst Brandt
Hajo writes:
That depends on what is plated onto the disk, but why plate it? It
seems that people are more concerned with appearances than function.
if you inspect the disks on a car you won't find any shiny metal.
Jobst Brandt <jbr...@hpl.hp.com>
Hans-Joachim Zierke
Jobst Brandt schrieb:
> I think we are mixing subjects here. The brake fluid for disks is
> subjected to higher temperatures than rim brakes. This was also true
> for automobile drum brakes at the advent of disks. New brake fluid
> had to be formulated.
Practical experience: I have no problems with my loadracing bike, that is
equipped with Sachs disks front and rear, as long as I stay on the road.
There are also no really long descents during my commuting trips: Maybe 150
m height difference max.
It is also no problem if I carry additional 70 kgs of load.
On the other hand, I quickly noted problems as soon as I traveled off road.
I once traveled down a very narrow, very steep trail with lots of hairpins,
and at the bottom, the brakepads were in slight contact even without
braking.
I'm quite sure I could go down the Großglockner Hochalpenstraße with this
bike without problems. I wouldn't bet for it in fully loaded condition.
But... at least until today, I did not get the idea to pass the "12% auf 16
Kilometer" sign with a 70 kg load...
hajo
Hans-Joachim Zierke
Jobst Brandt schrieb:
> That depends on what is plated onto the disk,
With Sachs disks, it very much looks like nickel plating
> but why plate it? It
> seems that people are more concerned with appearances than function.
> if you inspect the disks on a car you won't find any shiny metal.
The engineers of the German automotive use a disfunctional huge CAD program
like Catia for a single reason: It is better than others suited to create
curved shapes without the slightest of imperfection.
If the consumer could see the disks of a car, they would be plated.
hajo
Matt O'Toole
Hans-Joachim Zierke <ha...@Hanta.Berlin.Zierke.com> wrote in article
<slrn6e112...@hanta.Berlin.Zierke.com>...
> My problem with aluminum disks has been, that the transition from wet
> braking to no-longer-wet braking was so sharp, that I got rid of them in
> favour of steel disks.
Could this problem be solved with a better matched pad material? I imagine
the sudden transition occurs when the last of the water boils off the brake
parts, causing a sharp rise in temperature.
Matt O.
Matt O'Toole
Jobst Brandt <jbr...@hpl.hp.com> wrote in article
<6bq101$r...@hplntx.hpl.hp.com>...
> Water intrusion is a major problem because it makes steam. Steam is a
> compressible fluid and renders the brakes useless even before a poorly
> formulated fluid will vaporize. Corrosion is a secondary problem.
> Less apparent is that brake fluid is hygroscopic and for this reason
> master cylinders on cars are sealed from the atmosphere by a rubber
> bellows expansion element to allow for reduced reservoir fluid due to
> brake pad wear.
Yes, yes, but you're assuming water is getting in there is a given. If you
don't believe the system can be sealed for a reasonable time, then by all
means, go glycol. Cars can successfully use non-hygroscopic silicone brake
fluid for as long as glycol without problems, if it's installed in a fresh,
new, dry, sealed system to begin with. I don't see why an oil based system
can't be the same. Regular fluid changes would be a prudent with glycol
anyway, to make sure it's not too "wet." The same regimen applied to oil
might yield the same result. So, if you're going to be changing your fluid
regularly, why not make it easy, to be more sure it gets done?
> Of what is MMC a matrix?
Yes. Neat-O, cheap-o aluminum with aluminum oxide mixed in (there are
other, more exotic types also). It's being used successfully for brake
rotors in motorsports, mostly by amateur time trialists, etc. It's been
played with enough by (real) engineers that the properties are pretty well
known, good pads are able to be developed, etc. You won't see it much in
most racing, because anything but cast iron rotors are banned, except in
F1, where they use carbon-carbon composites already anyway. MMC rotors may
show up as a weight saving feature in some new, efficiency minded show
cars, etc.
> Aluminum works if it is hard anodized,
> however, anodizing is an insulator that causes high surface
> temperatures as we see on anodized rims.
So, we're back to the same problem we have with steel. Plus, anodizing
will wear off, and we'll have to buy hideously marked up replacements all
the time.
> An aluminum disk with a
> metal-spray steel coating would be better but expensive.
Now there's an idea, but yes, it might be expensive. I bet MMC discs would
be cheaper.
With respect to Mr. Magoo-ra, if you humiliate these guys too much, they
might not come back. Most of them are afraid to enter the fray already.
Their industry BS doesn't get discussed and refuted, and no one learns
anything.
Matt O.
Richard Horrocks
Hans-Joachim Zierke <ha...@Hanta.Berlin.Zierke.com> wrote in article
<slrn6e1pd...@hanta.Berlin.Zierke.com>...
>
> Jobst Brandt schrieb:
> > but why plate it? It
> > seems that people are more concerned with appearances than function.
> > if you inspect the disks on a car you won't find any shiny metal.
>
> Hajo wrote
> If the consumer could see the disks of a car, they would be plated.
>
This is sadly true and was the case on motorbikes for many years. many
people were killed and injured cos the Japanese (mainly) bike manufacturers
were more worried about the looks than the function of their disc brakes.
Ducati/BMW etc all stuck to cast discs like Brembos and sucks to the dull
look and rust if it rains, they WORK!
Cheers
Richard
Brodkin Panu
thorsten schaette (gor...@omegabbs.com) wrote:
: >Does the mineral oil used in Maguras expand so much (tens percents) ??
: yup it does, thats why we have a huge ( comparable) reservoir
BUT dot3&4 -oils does not expand so much. (Silicon based dot5 expands
more .. but not even nearly much as normal mineral oils. In comparison
the dot5 fluids has the highest boiling points - So dot5 seems to be
the best fluid for brakes with big reservoirs. You should try the
dot 5 ..)
: >: Why is Hayes using enviromental harmfull dot brake fluid ? Sure not
Don't know about the environmental or biological effects ...
but silicone dot5 fluids doesn't melt paintings or irritate skin etc.
(I think that this was one of Your reasonings agains the dot3&4.)
: Everybody has a heat expansion problem, there are just more or better
: ways to solve the problem.
You must realise that this problem GREATLY depends on the fluid used.
Fluids with large volume/heat factor expand much and feels soft.
(When you apply pressure to this kind of a fluid it compresses and
heats .. And when you apply heat to the fluid it expands ..)
SO the smaller volume/heat factor the stiffer (resists against
heat / compression & expanding) the fluid - the properties of
fluid effects dramatically the operation of the brake !!
(Therefore the use of brake fluids wich have very high
boiling points and small vulume/heat factor.)
This all makes me wonder the use of mineral oils ..
(DOT5 silicone would make more sense to me.)
: Ours are much more like a motorcycle, Our piston floats and has two
: pistons on one side, just like car or motorcycle brakes. Yes there are
: some Motorcycles with floating disks ( like formulas ) but very few.
OK. But I think that dragging noises does not bother so much on motorcycles.
It doesn't matter much wich part flotates - as long as the brake pads
doesn't touch the rotor when not braking.. (And I have heard that
early Maguras did have dragging problems.)
: We sure do, and I am happy to discuss this further.
: just email me and we can 'talk' .
: I am also more than happy to send you some technical information,
: which might explain a few things better, than i can, typing this late
: in the evening. : -)
I feel that this kind of discussions should be open and
constructive. At least the openess fullfills here in
the newsgroups ..
: Kind of ! But bicycle discs are a different kind of animal all
: together.
Seems to be matter of taste ...
: I hope I didnt offend you in any way, if I did, please accept my
: apologies.
Not much offends me in any way (even if meant ;-)
Tim Heinemann
On 11 Feb 1998 06:46:43 GMT, "Matt O'Toole" <ma...@deltanet.com> wrote:
>
>
>Jobst Brandt <jbr...@hpl.hp.com> wrote in article
><6bq101$r...@hplntx.hpl.hp.com>...
>
>> Water intrusion is a major problem because it makes steam. Steam is a
>> compressible fluid and renders the brakes useless even before a poorly
>> formulated fluid will vaporize. Corrosion is a secondary problem.
>> Less apparent is that brake fluid is hygroscopic and for this reason
>> master cylinders on cars are sealed from the atmosphere by a rubber
>> bellows expansion element to allow for reduced reservoir fluid due to
>> brake pad wear.
>
>Yes, yes, but you're assuming water is getting in there is a given.
It is a given, that´s why they invented the latest avaible standard
for brake fluids, DOT5, which is claimed to be non-hygroscopic...
and even this should be replaced after 5 years (compared to the
2 years for Dot3 or 4)
>If you
>don't believe the system can be sealed for a reasonable time, then by all
>means, go glycol. Cars can successfully use non-hygroscopic silicone brake
>fluid for as long as glycol without problems, if it's installed in a fresh,
>new, dry, sealed system to begin with.
That´s it! You do not get maiden parts if you buy bicycle hydrobrakes,
and so the manufacturer determines what kind of fluid you have to use!
And in case of the Magura I doubt that you might use DOT5 or like in
a system the components of which were designed to be used with
mineral oil.
>> An aluminum disk with a
>> metal-spray steel coating would be better but expensive.
>
>Now there's an idea, but yes, it might be expensive. I bet MMC discs would
>be cheaper.
In MC world there is one standard, and that´s a cast iron floating
dics as you said (appart from GP racing where they use a combination
of cast iron and carbon composite to get the best of both), and that´s
not because of some kind of ideologically based banning but because
these have proven to deliver the best results. Carbon Compo discs are
no alternative as they need high temperatures to work which are not
achieved by bikes 99% of time. And I don´t see the point in MMC, as
the braking surface is aluminum they will have the same effect as
ordinary aluminum.....and as soon as they are worn down to the point
were the "fibre" part begins they will change their braking mode
again....
MMC might have a reason in frame building, that´s were the anisotropic
part of this material might be of use, but I can´t see any kind of
advantage over standard dics made of aluminum (perhaps they are
10g lighter......)
Tim Heinemann
>>> Than this old Harley thingy. Can you find anybody on this planet who
>>> tells you that Harley brakes are any good ???
>>I bet I could, if I cared enough to want to go searching.
>I am sure you will( might take you a little while though ) , but
>believe me, although Harleys are nice, the brakes are not a strong
>point. On BMW motorcycles however, the brakes are mated to the
>performance and generally getting praises .
>And although I dont want to make this a huge own advertising, : BMW's
>Motorcycles have Magura Brakes on it.
AFAIK they use Brembo, as this is what I can read on the calpers of
those BMW around here......and there are a lot of repalcement manu-
facturers like Spiegler (8 piston calipers and discs), Bakker (dutch
manufacturer of the QCS chassis, a dual swinging arm layout, who
build the first 6piston caliper years before Nissin....) G&G who have
a patent of a floating point piston which allows the brake pad to move
slightly so that it allways toches the disc with its full surface (not
sure if they use this in there bicycle brakes if they are on the
market all ready....) and so on...
Brembo is also the oem for Ducati, and these are famous for trouble
with brakes which are of the same type as those on a BMw, Bimota or
the like compared to them....but it´s allways Ducati who need work
on their brakes (appearntly nobody knows why), so there is an
aftermarket for these mcs as well!
>>> Or can you find actually
>>> hundreds of brake people who manufacture Harley replacement brakes .
> I dont know of anybody who makes aftermarket brakes for BMW. There is
>simply no need to improve on an excellent brake.
>>I think I could find hundreds of people who manufacture replacement
>>ANYTHING, harley or otherwise. Thats a bit silly..
>Nope, if there is no need to improove something, than there will be
>very little activity in this marketsegment.
That´s right, the manufactures i mentioned above are way less numerous
than those who say they build a better brake for HD Mcs . I know at
least 10-12 different manufacturers, and a lot of them tell that
their brake calipers look better than standard which tells enough
about the average motivation of Harley owners to change their
brakes........if I had bought this nice ´57 hardtail Panhead instead
of the Norton I use now it would have had a pair of Brembo 4piston
calipers which would have grabbed their teeth in a pair of floating
cast iron discs......but that´s not the subject, I know! ;-)
>>> And what brakes is every Harley Racer using ( if it is allowed by the
>>> racing authorities to change the brakes ) Hayes ???
>Lets say most racers are using Magura Mastercylinder, some also use
>Performance Machine.
I have not seen a lot of Magura Hydraulics on Motorcycles here in
Germany, especially not on the racing sportsters i know...they use
PM if they want a "Custom Look" and Brembos or Nissins taken
from top-range jap big bikesd if they want good brakes!
>>I have absolutley no idea. I told you FOR INFORMATION ONLY. You
>>seem to need more information than I can provide. Perhaps you
>>should contact Hayes yourself and talk to them? Oh look, theres
>>the number!
>I know. But again. I was trying to ask questions, instead of simply
>touting our own horn.
>> 3 times consecutive Worldchampion, 1,2 pro Men 1,2,4 Pro Women USA
>>> Downhill Championships, Silver in the DH Worlds ...
>see, thats what I mean, I dont want to sound obnoxious Of course I
>believe in our own stuff. The DH results across the world are facts,
>NOT advertising.
But they are used for advertising, and the raeson why your and all the
other companys to this is to promote....or do you think Volkswagen
wants to spend all the expences of the GT-Team (or was it Trek)
because it´s nice to waste money?
Tim Heinemann
>: no heat problem because of heat expansion reservoir. Yup, that works !
>I think that the boiling is still a problem. With expansion reservoir
>You'll lose all braking power when the fluid boils .... No good ...
As well as without a reservoir.......
>: But how big is that reservoir ? Is it big enough to allow all the
>: fluid to expand , when the going gets tough ?? What works for mild
>: cross country might not be enough for a real downhill !
>Does the mineral oil used in Maguras expand so much (tens percents) ??
>
>: Why is Hayes using enviromental harmfull dot brake fluid ? Sure not
>Why should the fluid leak to the ground ?? (Does Your leak ?)
In case of an accident, e.g.! Lay your bike down somewhere in the wood
in this unpleasant special way and the loop created by your
hydro-lines might be pulled out by something...and that´s NO matter
what kind ar manufacturer of brake....
>
>: because they have no heat expansion problem. You write about warping
>Maybe they do not have such expansion problem because of the use of
>brake fluids - I'll bet there is a reason for calling it the brake
>fluid ..
>
>: discs, better than whom's discs ???
>Formulas (Paiolis) discs are similar to motorbike discs (especially
>the flotating mounting) - I'll bet again that the motorbike construktion
>has the reasons ...
Magura does the floating in the caliper as well as Sachs, so it´s 1:1
here regarding construction principles....by the way, newer Formula
discs LOOK like floatingly mounted, but they aren´t in fact, They re-
placed the Floating mounts by some horrible kind of rivets on the
disc I bought about a month ago. An older disc had real floating
mounts....by the way, afaik Hayes brakes do have a fixed caliper
and a solid disc, so this would mean no floating at all! Well, Hope
brakes are fixed in every way, and they work quite well.....
Tim Heinemann
>> Than this old Harley thingy. Can you find anybody on this planet who
>> tells you that Harley brakes are any good ???
>
>I bet I could, if I cared enough to want to go searching.
Okay, then ask him if he愀 a liar, he tells you "nop", and you愉e
where you left.......Harley brakes are the worst avaible in these
days, that愀 why they are the first item replaced on a bike owned
by a HD RIDER (not those who do own them as a poseur bike for
Daytona, sturgis and the local ice cream bar.....if they change the
calipers they buy chromed shit, just like a lot of Jap cruisers)
Tim Heinemann
>>: discs, better than whom's discs ???
>>Formulas (Paiolis) discs are similar to motorbike discs (especially
>>the flotating mounting) - I'll bet again that the motorbike construktion
>>has the reasons ...
>Ours are much more like a motorcycle, Our piston floats and has two
>pistons on one side, just like car or motorcycle brakes. Yes there are
>some Motorcycles with floating disks ( like formulas ) but very few.
Oh, there are in fact not a few with floating discs, it愀 the majority
of race bikes and race replicas.......those who need lots of stopping
power have them usually. That does of course not change the fact that
a floating caliper works well, too........
evans-the-swim
"Matt O'Toole" <ma...@deltanet.com> wrote:
>> An aluminum disk with a
>> metal-spray steel coating would be better but expensive.
>Now there's an idea, but yes, it might be expensive. I bet MMC discs would
>be cheaper.
A long time ago I was looking at a plasma-coated Al disk for my
(motor)bike - it was about $100-150 US then. Stock Honda was
stainless; so's the Grimeca on my Gitan, as are the two Shimano
cable-discs on a beater in the garage. Who makes (bi)cycle size
cast-iron ones?
Ole Blokhus
On 12-Feb-98 18:17:46, "Tim Heinemann"
<TimHendrik.Hei...@post.rwth-aachen.de> wrote:
>>: no heat problem because of heat expansion reservoir. Yup, that works !
>>I think that the boiling is still a problem. With expansion reservoir
>>You'll lose all braking power when the fluid boils .... No good ...
>As well as without a reservoir.......
Nope, you'll just end up with rubbing or seized brakes until the fluid cools
down.
>>: because they have no heat expansion problem. You write about warping
>>Maybe they do not have such expansion problem because of the use of
>>brake fluids - I'll bet there is a reason for calling it the brake
>>fluid ..
>>
>>: discs, better than whom's discs ???
>>Formulas (Paiolis) discs are similar to motorbike discs (especially
>>the flotating mounting) - I'll bet again that the motorbike construktion
>>has the reasons ...
>Magura does the floating in the caliper as well as Sachs, so it愀 1:1
>here regarding construction principles....by the way, newer Formula
>discs LOOK like floatingly mounted, but they aren愒 in fact, They re-
>placed the Floating mounts by some horrible kind of rivets on the
>disc I bought about a month ago. An older disc had real floating
>mounts....by the way, afaik Hayes brakes do have a fixed caliper
>and a solid disc, so this would mean no floating at all! Well, Hope
>brakes are fixed in every way, and they work quite well.....
Hope, Formula and Hayes all use dual sided calipers. That way they don't need
a floating disc or floating caliper. Since the dual pistons are hydraulicly
(sp?) connected, the pads will move with the disc if the disc is warped, much
like cantilever brakes on an out-of-true wheel. This is in my opinion a much
better solution than floating this or rattling that. The pads completely
retract from the disc, and no rubbing what so ever occurs.
Ole.
--
Ole Blokhus
ol...@powertech.no
Tim Heinemann
>>>You'll lose all braking power when the fluid boils .... No good ...
>
>>As well as without a reservoir.......
>
>Nope, you'll just end up with rubbing or seized brakes until the fluid cools
>down.
But your brakes decide wether it´s stop or go, and I don´t like
this....what I wanted to express is that you loose control!
>Hope, Formula and Hayes all use dual sided calipers. That way they don't need
>a floating disc or floating caliper. Since the dual pistons are hydraulicly
>(sp?) connected, the pads will move with the disc if the disc is warped, much
>like cantilever brakes on an out-of-true wheel. This is in my opinion a much
>better solution than floating this or rattling that. The pads completely
>retract from the disc, and no rubbing what so ever occurs.
Brake discs are floating because a warped disc does increase wear and
decrease stopping power and modulation as the pads do not touch the
warped disc with their full surface! On a bike this is not as
important as on a motorcycle, that´s true, but there is a very good
reason for floating mounts in engineering.......they are not a
marketing trick! And afaik it was brembo´s design which formula wanted
to copy, maybe that´s marketing, but Brembo´s are (and have been for
long!!) amongst the best disc brake designs.
LCha357877
Someone say tandem? we are using the sucks, opps I mean Sachs
disk on our off road tandem with a MOTO 120 fork. I got it so it would not rub
when I set it up. It works OK, but the V brake worked better. On the first real
test the disk brake failed! downhill
500 lbs of ridders and bike at 56 MPH ! the disk warped and ate the pads up.
Sachs did warranty the parts, we installed the stell disk
wich looks to be holding up but over all I'm not impresed with this brake would
like to try the Hays disk
Brodkin Panu
Tim Heinemann (TimHendrik.Hei...@post.rwth-aachen.de) wrote:
: >: no heat problem because of heat expansion reservoir. Yup, that works !
: >I think that the boiling is still a problem. With expansion reservoir
: >You'll lose all braking power when the fluid boils .... No good ...
: As well as without a reservoir.......
Well .. I think that brakes without reservoir would lock up in some
decree. (The pressure caused by boiling has no way to escape ..)
: >Formulas (Paiolis) discs are similar to motorbike discs (especially
: >the flotating mounting) - I'll bet again that the motorbike construktion
: >has the reasons ...
: Magura does the floating in the caliper as well as Sachs, so it´s 1:1
So does the Formula ... Double sided hydraulically coupled pistons
DO flotate !
: here regarding construction principles....by the way, newer Formula
: discs LOOK like floatingly mounted, but they aren´t in fact, They re-
: placed the Floating mounts by some horrible kind of rivets on the
: disc I bought about a month ago. An older disc had real floating
I got the older Fromula .. I have heard that the flotating mounts
on the disc prevents the heat warping effect.
: mounts....by the way, afaik Hayes brakes do have a fixed caliper
: and a solid disc, so this would mean no floating at all! Well, Hope
: brakes are fixed in every way, and they work quite well.....
I thought that Hope has double sided pistons ... (Please confirm ..)
Brodkin Panu
Tim Heinemann (TimHendrik.Hei...@post.rwth-aachen.de) wrote:
: >Nope, you'll just end up with rubbing or seized brakes until the fluid cools
: >down.
: But your brakes decide wether it´s stop or go, and I don´t like
: this....what I wanted to express is that you loose control!
But malfunction in extreme conditions should be stopping
in BRAKES. (Or You'll end having speed up and no brakes downhill !!)
: >Hope, Formula and Hayes all use dual sided calipers.
That's confirms my thoughts ..
: Brake discs are floating because a warped disc does increase wear and
: decrease stopping power and modulation as the pads do not touch the
: warped disc with their full surface! On a bike this is not as
: important as on a motorcycle, that´s true, but there is a very good
: reason for floating mounts in engineering.......they are not a
: marketing trick! And afaik it was brembo´s design which formula wanted
: to copy, maybe that´s marketing, but Brembo´s are (and have been for
: long!!) amongst the best disc brake designs.
I agree again ..
Ole Blokhus
On 14-Feb-98 11:50:50, "Tim Heinemann"
<TimHendrik.Hei...@post.rwth-aachen.de> wrote:
>Brake discs are floating because a warped disc does increase wear and
>decrease stopping power and modulation as the pads do not touch the
>warped disc with their full surface! On a bike this is not as
>important as on a motorcycle, that´s true, but there is a very good
>reason for floating mounts in engineering.......they are not a
>marketing trick! And afaik it was brembo´s design which formula wanted
>to copy, maybe that´s marketing, but Brembo´s are (and have been for
>long!!) amongst the best disc brake designs.
So how warped does your MTB discs become? On my Hopes, the discs are slightly
warped, but not more than maybe .5mm side to side, and that's once per
roataion. There's no way I can feel any effects of that, the deviation from
parallell to the pads is way too small. Maybe if the disc was warped 1mm on 5
spots... Besides, the discs on most MTBs are thin and flexible, and will
follow the pads when you brake.
Ole Blokhus
ol...@powertech.no
Tim Heinemann
On Sat, 14 Feb 1998 10:50:50 GMT,
TimHendrik.Hei...@post.rwth-aachen.de (Tim Heinemann)
wrote:
>
>>>>You'll lose all braking power when the fluid boils .... No good ...
>>
>>>As well as without a reservoir.......
>>
>>Nope, you'll just end up with rubbing or seized brakes until the fluid cools
>>down.
>
>But your brakes decide wether it愀 stop or go, and I don愒 like
>this....what I wanted to express is that you loose control!
To make this one clear: Of course it愀 better to have a lockup in the
brake system rather than a complete failure if you愉e to descend a
steep mountain, I agree! It愀 perfectly clear that the heat will not
be generated so fast that your brakes will send you off via the
handlebars........maybe I didn愒 express this in the right way!!!!!!!!
But in either case your brake does not work (apart from the difference
which might take you straight into an ambulance or coffin, no
question...)
And I hope we do agree that the best design would be a reservoir to
cope with expansion AND a heat-tolerating fluid to cope with to much
expansion!!
Tim Heinemann
On 15 Feb 1998 16:25:55 GMT, bro...@ele.tut.fi (Brodkin Panu) wrote:
>: >Formulas (Paiolis) discs are similar to motorbike discs (especially
>: >the flotating mounting) - I'll bet again that the motorbike construktion
>: >has the reasons ...
>
>So does the Formula ... Double sided hydraulically coupled pistons
>DO flotate !
needed to push the pistons in (and out on the other side) is much
bigger than that needed to move the disc on its pulley or the caliper
on its mounting! A floating disc is the BETTER design, but this does
not mean a non-floating design does not work, and the differences are
relativly small between these designs, and they might well be too
small to have an effect in bicycle brakes!! And in case of the older
Formula discs the floating might even be spoiled by the fact that the
very small surface of the disc which touches the floating mounts will
dig into its bearing surface....
Tim Heinemann
On 15 Feb 98 18:08:56 +0100, Ole Blokhus <nospam...@powertech.no>
wrote:
>So how warped does your MTB discs become? On my Hopes, the discs are slightly
>warped, but not more than maybe .5mm side to side, and that's once per
>roataion. There's no way I can feel any effects of that, the deviation from
>parallell to the pads is way too small. Maybe if the disc was warped 1mm on 5
>spots... Besides, the discs on most MTBs are thin and flexible, and will
>follow the pads when you brake.
You are perfectly right regarding Bicycle brakes, there is indeed no
real need for floating discs, but -as I said before- there is a reason
for them on MC designs: These disc are way thicker and stiffer, of
course, and on a 270kph+ Ducati 916 you feel the difference between
floating and non-floating brakes I bet! So my conclusion at least is
that -even if you really do not need them on an MTB- floating discs do
no harm either (exception: the price, okay...). By the way, perhaps
you read it before: The new Formula discs are no longer floating in
the true sense of the word, the clip-on bearings were dropped in
favour of rivets which work loose slightly and imitate some kind of
floating, but they work well on my bike. And the Hope was one of the
best brakes in a recent test for a German bike mag which stated that
it had neglactible differences in dry-to-wet handling...
Jobst Brandt
I think there is a basic problem with disk brakes that is being
overlooked, and that is their need for a high mechanical advantage.
The pads are made of hard material that although having a low
coefficient of friction is less affected by moisture and temperature.
The high mechanical advantage required to make these hard pads work
initially caused the auto industry endless grief until it was decided
that the pads may drag when the brake released. This was in the days
when power brakes were not accepted as necessary or desire-able.
Toady, brake pads on motorized vehicles drag most of the time.
For bicycles, that have so little excess power that racers open the QR
on their rear caliper brakes on hill climbs to avoid intermittent pad
contact, disk brakes that drag are not acceptable. For this reason
disks on bicycles are reliving the problems of early auto disks but
even more so because the dragging brake is not only inelegant, it
materially impedes motion. It may not be possible to make a manually
operated disk brake that does not drag and once that is accepted as a
design criterion, some of the other problems may find a solutions.
Jobst Brandt <jbr...@hpl.hp.com>
Matt O'Toole
Jobst Brandt wrote in message <6ccil6$l...@hplntx.hpl.hp.com>...
Several of the brakes currently on the market do run drag-free: at least
until the disc warps. These brakes really do work well for a single rider
on a mountain bike. They're strong, fade free, drag-free, reliable, and
less affected by water and dirt than rim brakes. However, they're
definately targeted at mountain bikes, and may be inadequate for tandem use.
It may be that no one has built an appropriate disc brake for a tandem yet.
It seems to me that a tandem requires a much bigger brake than a mountain
bike, just as a Suburban requires a much bigger brake than a Civic.
Matt O.
Brodkin Panu
Jobst Brandt (jbr...@hpl.hp.com) wrote:
: It may not be possible to make a manually
: operated disk brake that does not drag and once that is accepted as a
: design criterion, some of the other problems may find a solutions.
I thought this one day ...
I think it would be possible to use double piston levers.
There would be bigger one to move the pad clearance with
very low mechanical advandance. (The stroke of the piston
would be adjustable to cover only the clearance part -
stop screw or something ..) The smaller piston would
have high mechanical advantance to be used with power
braking. A reservoir in hydraulic circuit would handle
any density variations of the fluid. (I think that
the mechanical dimensions of the brake system
changes very little with temperature ..)
(Hope You got it ... This morning isn't one of the bests ..)
Jobst Brandt
Brodkin Panu writes:
>> It may not be possible to make a manually operated disk brake that
>> does not drag and once that is accepted as a design criterion, some
>> of the other problems may find a solutions.
> I had this thought one day ...
> I think it would be possible to use double piston levers. There
> would be bigger one to move the pad clearance with very low
> mechanical advantage. (The stroke of the piston would be adjustable
> to cover only the clearance part - stop screw or something ..) The
> smaller piston would have high mechanical advantage to be used with
> power braking.
This concept has interested many inventors and engineers for a long
time. Upon closer examination, it becomes apparent that it violates a
basic law of leverage, and cannot be done passively (without power
assist). Items like this are offered now and again by people who are
not engineers and are not familiar with the technology. It makes me
wonder in how low esteem scientists are held in general, for not
having investigated the "obvious". Hoyt McKagen recently expounded on
that at length, but I take it he is not the norm.
> A reservoir in hydraulic circuit would handle any density variations
> of the fluid. (I think that the mechanical dimensions of the brake
> system changes very little with temperature ..)
The expansion of fluid takes place in the caliper cylinder where the
temperature is high enough to cause steam. This is not merely a
volume problem, but rather a gas spring that makes brake application
impossible while at the same time causing brake drag when released.
Jobst Brandt <jbr...@hpl.hp.com>
John Olsen
Nobody. Nobody would buy them. Even though they provide
a superior braking experience, they rust and they are heavy. All
of the current ATB discs are either stainless, metal matrix, or
hard-anodized aluminum. I've had good luck with both stainless and
anodized aluminum discs.
John Olsen
In article <6ccil6$l...@hplntx.hpl.hp.com>, jbr...@hpl.hp.com (Jobst Brandt) says:
>
>I think there is a basic problem with disk brakes that is being
>overlooked, and that is their need for a high mechanical advantage.
>The pads are made of hard material that although having a low
>coefficient of friction is less affected by moisture and temperature.
>The high mechanical advantage required to make these hard pads work
>initially caused the auto industry endless grief until it was decided
>that the pads may drag when the brake released. This was in the days
>when power brakes were not accepted as necessary or desire-able.
>Toady, brake pads on motorized vehicles drag most of the time.
>
>For bicycles, that have so little excess power that racers open the QR
>on their rear caliper brakes on hill climbs to avoid intermittent pad
>contact, disk brakes that drag are not acceptable. For this reason
>disks on bicycles are reliving the problems of early auto disks but
>even more so because the dragging brake is not only inelegant, it
>operated disk brake that does not drag and once that is accepted as a
>design criterion, some of the other problems may find a solutions.
>
I've used all the mountain bike discs on the market, and several can be
set up (with a moderate amount of care) to not drag at all. Say what you
will about disc brakes, but I wouldn't go back to rim brakes for off-road
use in a wet climate. Even if there were drag, I'd rather be a bit slower
up hills and on the level, but have great braking all the time. That
would not be the case if I rode on roads, or in a dry climate.
John Olsen
Matt O'Toole
John Olsen wrote in message <6ckpf5$1...@ender.techcenter.paccar.com>...
>I've used all the mountain bike discs on the market, and several can be
>set up (with a moderate amount of care) to not drag at all. Say what you
>will about disc brakes, but I wouldn't go back to rim brakes for off-road
>use in a wet climate. Even if there were drag, I'd rather be a bit slower
>up hills and on the level, but have great braking all the time. That
>would not be the case if I rode on roads, or in a dry climate.
So, which one is your favorite, and why? How long do pads and rotors last,
and how much does it cost to replace them? Which ones don't you like, and
why?
I look forward to when good disc brakes are commonplace and affordable.
Long, wet, off road descents take their toll on pads and rims. Discs could
make some really muddy riding a lot more viable, because of the extra tire
clearance. The precise modulation they provide is great for wet, technical
riding. Wet rocks and roots don't look so scary, when you can almost "feel"
your way down through them. Ever had your rims ice up when riding on snow?
Again, discs could be a big help.
I've tried a few disc setups, and liked most of them for the reasons I just
stated. The main thing that prevents me from buying them is the expense,
and not just the initial purchase. Bike companies habitually screw us badly
on replacement parts like brake pads and fork bumpers. A friend's
Rockshox/AMP disc goes through $30+ pads faster than I go through regular LX
pads. I also fear what a replacement aluminum rotor might cost, or worse, a
high-tech sounding "MMC" one.
Matt O.
Tim Heinemann
On Fri, 20 Feb 1998 20:55:57 -0800, "Matt O'Toole" <ma...@deltanet.com>
wrote:
>So, which one is your favorite, and why? How long do pads and rotors last,
>and how much does it cost to replace them? Which ones don't you like, and
>why?
The Formula is IMO the best MTB brake as with carefull adjustment it´s
allmost dragfree and the power is sufficient (my old V-Brake used to
have more stopping power but it was a binary brake and that´s slightly
stupid IMO) I haven´t tried the new lever with expansino chamber yet
but a friend uses this one and he´s not very lucky with it as the
lever´s way to cover the small expansion hole is way to far! I use the
old lever in CC riding, no huge downhills and they work perfectly for
this application and never had a problem with fluid expansion. I can´t
tell you how long the pads last as I haven´t used the brakes for more
than three months yet but wear is not measurable after appr. 500 km.
Compared to the old V this sounds quite nice as this stupid thing used
two pairs of pads during the 400 km I had to ride them as there were
some problems with the old Formula caliper which doesn´t fit a lot of
forks.
Our local university did a test on disc-brakes two years ago and it
were the Formula, Hope and Pro Stop which delivered the best
overall results, the Magura design suffered slightly from it´s
floating piston design but was said to be the most reliable as it had
no problems with overheating during the test--other than the Formula
which does of course lock up when hot, but this is no problem in CC as
I stated before. The AMP was stated to be quite powerfull, but the
cable pull design deteriorated the modulation.
>I look forward to when good disc brakes are commonplace and affordable.
Me too, but this will take some years, I think, so I decided to buy a
disc setup now and not then--and I´m quite happy with it, and at least
on one of my bikes there won´t be anything else than a pair of disc
brakes!
> I also fear what a replacement aluminum rotor might cost, or worse, a
>high-tech sounding "MMC" one.
Hmm, my Fromula manual says that the rotor (only the floating part,
but I´m not sure wether they sell the disc solo, without the pulley)
has to be replaced when it´s under 1mm (which sounds quite strange to
me, I´d rfeplaced at least at 1.5mm). I measured it when new and it
had about 2.6mm and this hasn´t changed on the recent 500km....
Matt O'Toole
I hope Mr. Olsen will respond to my last post.
Tim Heinemann wrote in message <34f0052a.270948@news>...
>The Formula is IMO the best MTB brake as with carefull adjustment it´s
>allmost dragfree and the power is sufficient (my old V-Brake used to
>have more stopping power but it was a binary brake and that´s slightly
>stupid IMO)
If the disc doesn't stop better than a V-brake, why bother with the added
weight, complexity, and most of all, the expense? By "binary," I assume you
mean that the V-brake didn't modulate well. Most I've tried were fine, once
you got used to the low lever effort. Some have adjustable-leverage levers,
and a few different pad compounds are available. Surely, you could find a
good setup, as most people are able to.
There are other reasons to choose discs, however, and I'll give you that.
>I haven´t tried the new lever with expansino chamber yet
>but a friend uses this one and he´s not very lucky with it as the
>lever´s way to cover the small expansion hole is way to far! I use the
>old lever in CC riding, no huge downhills and they work perfectly for
>this application and never had a problem with fluid expansion. I can´t
>tell you how long the pads last as I haven´t used the brakes for more
>than three months yet but wear is not measurable after appr. 500 km.
>Compared to the old V this sounds quite nice as this stupid thing used
>two pairs of pads during the 400 km I had to ride them as there were
>some problems with the old Formula caliper which doesn´t fit a lot of
>forks.
Hmm. It sounds like that product may need some more development.
>Our local university did a test on disc-brakes two years ago
Is this published? Why would a university want to test bicycle brakes? Was
it an engineering student's thesis or something?
>and it
>were the Formula, Hope and Pro Stop which delivered the best
>overall results,
I was really impressed with the Hope. However, my good experience with it
may have been partly due to several stream crossings, which cooled it off
before it faded on me.
>the Magura design suffered slightly from it´s
>floating piston design
How, what does that mean?
>but was said to be the most reliable as it had
>no problems with overheating during the test--other than the Formula
>which does of course lock up when hot, but this is no problem in CC as
>I stated before.
I guess it depends on your "CC" use. Here in California, definately in
Colorado, and probably in other places, "CC" rides consist of a huge climb
of several thousand vertical feet, followed by a huge descent of the same.
On these descents, all brakes fade, and discs suffer their own problems. I
cannot even imagine what descending the Alps on a tandem would be like!
Shimano brake pads fade worse, though. The best braking I've experienced
has been with aftermarket rim brake pads, followed by discs like the Hope
and AMP (they fade too much), and last, brakes with Shimano pads. Those not
only fade terribly, they wear so fast that the levers start to bottom out at
the end of a long descent, requiring an adjustment. Yes, I've had the
mispleasure of doing brake adjustments in the field. Shimano pads do work
well when wet, though.
>The AMP was stated to be quite powerfull, but the
>cable pull design deteriorated the modulation.
I've ridden the AMP, and did not find that to be the case. Modulation was
perhaps not as precise as other discs, but it was more predictable and
precise than V-brakes. Fade due to heat buildup was a problem, however, and
the brakes lost a lot of their power on a long descent. In this respect,
good rim brakes are better.
>Hmm, my Fromula manual says that the rotor (only the floating part,
>but I´m not sure wether they sell the disc solo, without the pulley)
>has to be replaced when it´s under 1mm (which sounds quite strange to
>me, I´d rfeplaced at least at 1.5mm). I measured it when new and it
>had about 2.6mm and this hasn´t changed on the recent 500km....
I hope not! That's not a lot of mileage. From what I've seen of AMP pads,
the cost of using these brakes is unacceptable to me.
It's supposed to be cheaper to ride a bike than drive a car!
Matt O.
Tim Heinemann
On Sun, 22 Feb 1998 22:24:25 -0800, "Matt O'Toole" <ma...@deltanet.com>
wrote:
>If the disc doesn't stop better than a V-brake, why bother with the added
>weight, complexity, and most of all, the expense? By "binary," I assume you
>mean that the V-brake didn't modulate well. Most I've tried were fine, once
>you got used to the low lever effort. Some have adjustable-leverage levers,
>and a few different pad compounds are available. Surely, you could find a
>good setup, as most people are able to.
On my bike the setup was quite miderable due to a slightly worn front
rim, but I tried several other v-setups and none of them had an
adequate modulation compared to a magura rim brake which in turn does
not reach the modulation of my formula setup. With the Formula it
besame much easier to descend a slippery trail as the front brake was
useable by now-- the v-brake tended to lock up as soon as the surface
changed to slightly slippery so I had to be much faster in reaction
than with the disc. As I said I trace this more to the rim than to the
v-principle but the formula is superior on my bike....
>
>There are other reasons to choose discs, however, and I'll give you that.
These --not the stopping power--- were my reasons: modulation, no
more wear on a chassis´s part and of course a faible for high-tech
which helps a lot regarding the overall price......
>Hmm. It sounds like that product may need some more development.
There isn´t a perfect disc brake on the market, each needs some more
development!
>>Our local university did a test on disc-brakes two years ago
>
>Is this published? Why would a university want to test bicycle brakes? Was
>it an engineering student's thesis or something?
It was published in two German bike magazines: bike 2/97 and Mountain
Bike 5/97. It was quite interesting to read that the results were
somehow different allthough it was the same test they referred to.
This test was made at the "Lehrstuhl fuer Maschinenelemente" and they
do a lot of research on bicycles.
>>the Magura design suffered slightly from it´s
>>floating piston design
>
>How, what does that mean?
A floating caliper allways touches the disc as this is it´s working
principle, the piston is free to move laterally but it´s the disc
which holds it in place.....this means friction, of course, and they
said it´s not enough to bother downhillers but to much for CC
>I guess it depends on your "CC" use. Here in California, definately in
>Colorado, and probably in other places, "CC" rides consist of a huge climb
>of several thousand vertical feet, followed by a huge descent of the same.
Well, we have a row of short climbs here, about 100 feet,than a
descent of the same and so on......and the formula gets hot on thos
terrain, so it would not be the brake I´d use in the Alps (or
rockies..), but they suit my riding and the terrain where I ride....
>I hope not! That's not a lot of mileage. From what I've seen of AMP pads,
>the cost of using these brakes is unacceptable to me.
No that´s not a lot of mileage, of course......I´ll tell you as soon
as I replace them how long they work. By the way, at least here in
germany the AMP isn´t a good deal in any way, it´s top of the range
in price, it cost much more than a Formula or Hope, and the rockshox
is not so much cheaper (still more than the other two..) Prices in DM
are: AMP ca. 900,- per wheel, Rockshox 750,- front/ 950,-rear ,
Formula 600,- front, 700,- rear, Hope 700,- front, 900,- rear, Magura
700,- front, 900,- rear.....these are appr. the official prices, but
at least in case of the Formula and Magura they are a lot cheaper to
obtain if you know where to buy (and do not care about a local
service....)
>
>It's supposed to be cheaper to ride a bike than drive a car!
Depends on what kind of bike and car, n-ést-ce pas? ;-)
Cy Galley
Jobst Brandt wrote in message <6ci8qm$h...@hplntx.hpl.hp.com>...
>The expansion of fluid takes place in the caliper cylinder where the
>temperature is high enough to cause steam. This is not merely a
>volume problem, but rather a gas spring that makes brake application
>impossible while at the same time causing brake drag when released.
>
>Jobst Brandt <jbr...@hpl.hp.com>
This is true that the temperatures do go over 212 but that is also why they
do not use water. In aircraft usage, we use 5606 hydraulic fluid for low
speed low loads. (less than 5000 pound loaded planes and touch downs of
less than 125 mph.) A loaded tandem doesn't even come close to these
numbers.
Many disk brake pistons rely on O-ring roll to pull the piston back. When
the piston begins to slide after the O-ring is deformed. (flat sides) then
it time to replace.