Roller brakes: running friction?
pat.n...@iname.com
different from conventional brakes in that the inside of the brake drum
is filled with grease. This may cause the turning of the wheel to be
slightly heavier than usual, particularly in cold weather"
1. So they have running friction. Does anybody know anything more about
this?
2. They say that there should be 15 mm of play in the brake lever. That
is a lot of movement. Perhaps the gap between pad and drum needs to be
large to reduce the drag caused by the grease in the gap. Is that the
reason?
Pete Biggs
> Shimano says the following about their roller brakes: "Inter-M brake
> is different from conventional brakes in that the inside of the brake
> drum is filled with grease. This may cause the turning of the wheel
> to be slightly heavier than usual, particularly in cold weather"
>
> 1. So they have running friction. Does anybody know anything more
> about this?
Friction hasn't been a problem with the Shimano Nexus 7 roller brake that
I have some experience of, at least not in London's winters (which aren't
all that cold). The Inter-M roller brake is probably similar or better.
Special grease is available to add via a port, by the way.
Much more of an issue is the amount of drag in the actual hub gear system.
Hopefully that's been improved in the Inter-M.
> 2. They say that there should be 15 mm of play in the brake lever.
> That is a lot of movement. Perhaps the gap between pad and drum needs
> to be large to reduce the drag caused by the grease in the gap. Is
> that the reason?
I suppose so, but the play is only apparent when rocking a stopped bike
back and forth with the brake on. You don't notice it when braking
normally.
~PB
Pete Biggs
> pat.n...@iname.com wrote:
>> 2. They say that there should be 15 mm of play in the brake lever.
>> That is a lot of movement. Perhaps the gap between pad and drum needs
>> to be large to reduce the drag caused by the grease in the gap. Is
>> that the reason?
>
> I suppose so, but the play is only apparent when rocking a stopped
> bike back and forth with the brake on. You don't notice it when
> braking normally.
Sorry, I misunderstood what "play" you were referring to (there is some
fore & aft play too). I would what Shimano are talking about: "lever
travel".
>> That is a lot of movement. Perhaps the gap between pad and drum needs
>> to be large to reduce the drag caused by the grease in the gap. Is
>> that the reason?
Yes indeed.
Don't expect it to be a powerful brake! Advantages, though: reduced
cleaning and maintenance, zero rim wear, no need to have rim perfectly
true.
~PB
Not Responding
> Shimano says the following about their roller brakes: "Inter-M brake is
> different from conventional brakes in that the inside of the brake drum
> is filled with grease. This may cause the turning of the wheel to be
> slightly heavier than usual, particularly in cold weather"
Having ridden on these hubs for over a year, I'm fairly happy that any
effect is minimal and maybe only psychological. If I hadn't read the
Shimano website, I would be blissfully unaware of any theoretical
slowdown in cold weather.
> 1. So they have running friction. Does anybody know anything more about
> this?
I took the front wheel off did some comparative spinning with a
conventionally hubbed wheel. There wasn't a significant difference.
> 2. They say that there should be 15 mm of play in the brake lever. That
> is a lot of movement. Perhaps the gap between pad and drum needs to be
> large to reduce the drag caused by the grease in the gap. Is that the
> reason?
>
As another poster observes, you don't get disc brake standard instant
stopping with hub brakes but it is more than perfectly adequate.
My only dislike about the set up is that you can't /see/ anything. I get
these paranoid moments when I become convinced the brakes are dragging
and out of adjustment. With conventional brakes, a quick glance tells me
that no, it's not the brakes, it's me that is dragging and out of
adjustment.
pat.n...@iname.com
from Shimano:
"Turn the cable adjusting bolt of the brake unit or brake lever so that
there is about 15 mm of play in the brake lever."
"The amount of movement in the inner cable must be 14.5 mm or more when
the brake lever is depressed. If it is less than 14.5 mm, braking
performance will suffer, and the brakes may fail to work."
Perhaps that last sentence indicates that:
friction -> heat -> reduced performance
"If you apply the front Inter-M brake strongly while the bicycle is
stopped and then shake the wheel, you will notice that there is a small
amount of play in the brakes. This is normal, and will not cause any
problems at all while riding."
"The front Inter-M brake has a built-in power modulator which controls
the braking force applied to the hub. Noise is generated by the
operation of the power modulator when the brake is applied, but this is
not a sign of a malfunction."
Curiouser and curiouser.
Alex Rodriguez
n...@nowhere.dev.nul says...
>As another poster observes, you don't get disc brake standard instant
>stopping with hub brakes but it is more than perfectly adequate.
Adquate for what? I have a Nexus 7 and I can grab the brake till it touches
the bar and it only slows the bike down a bit. An adequate brake should be
able to lock up the wheel. If my bike had cantilever studs I would have gotten
rid of this brake. Especially since I just found out the brake weighs over
a pound.
-----------------
Alex
pat.n...@iname.com
>An adequate brake should be able to lock up the wheel.
Shimano says that the power modulator (a clutch) in the brake "prevents
the wheel from locking-up if the brake force is getting too strong."
See their picture at:
http://cycle.shimano-eu.com/publish/content/cycle/seh/nl/en/technical_service/faq_s/city_and_comfort_bike/how_does_the_power.html
usuals...@dev.null.invalid
i am looking at a ridgeback switch at the moment.
i was trying to get one with disk brakes but they're out of stock.
the guy in the shop said hub brakes are better anyway.
are you saying this isn't true?
what about hub gears (nexus 8) vs regular derailleurs (shimano deore)?
Clive George
news:d9pkqv$s47$3...@newsmaster.cc.columbia.edu...
> Adquate for what? I have a Nexus 7 and I can grab the brake till it
> touches
> the bar and it only slows the bike down a bit. An adequate brake should
> be
> able to lock up the wheel.
Apply the front brake sufficiently and it will be able to :-)
Seriously, the back brake shouldn't be doing much of the slowing anyway, so
being a bit crap isn't much of a problem. Unless the front brake is also
crap.
(This does not apply to tandems :-) )
cheers,
clive
Pete Biggs
> "Alex Rodriguez" <ad...@columbia.edu> wrote in message
> news:d9pkqv$s47$3...@newsmaster.cc.columbia.edu...
>
>> Adquate for what? I have a Nexus 7 and I can grab the brake till it
>> touches
>> the bar and it only slows the bike down a bit. An adequate brake
>> should be
>> able to lock up the wheel.
>
> Apply the front brake sufficiently and it will be able to :-)
>
> Seriously, the back brake shouldn't be doing much of the slowing
> anyway, so being a bit crap isn't much of a problem.
Agreed.
> Unless the front brake is also crap.
Roller brakes can be used up front as well. It's one way to make you ride
extremely carefully, I suppose ;-)
~PB
David L. Johnson
> the guy in the shop said hub brakes are better anyway.
>
> are you saying this isn't true?
Depends on what you mean. They don't lose stopping ability in the rain,
as many rim brakes/pads do. They last much longer. But in dry conditions
they do not stop as well, and there is the weight and residual drag.
>
> what about hub gears (nexus 8) vs regular derailleurs (shimano deore)?
Same sort of comments apply. They are less prone to
damage/fouling/fussiness than derailleurs, but adjustment is critical, and
they are less efficient.
I use a roller brake and a nexus-7 hub gear on my rain bike. Makes sense
for that.
--
David L. Johnson
__o | You will say Christ saith this and the apostles say this; but
_`\(,_ | what canst thou say? -- George Fox.
(_)/ (_) |
BJ
shimano roller rear brake (no clutch there, unlike the front). My bike
has cantilever bosses, so I kept the 7 spd hub but went back to v-brakes.
And that's one less cable to disconnect to get the wheel off as well. The
thing is packed with grease inside, and I think that contributed to the
rather draggy feel. Maybe it was just due to shedding the weight, but I
gained pretty much one gear on the hills of my commute after ditching it
(I got the thing in the first place as it seemed a reasonable idea for
all-weather commuting in a rainy climate).
news:d9pkqv$s47$3...@newsmaster.cc.columbia.edu:
Simon Brooke
('usuals...@dev.null.invalid') wrote:
> what about hub gears (nexus 8) vs regular derailleurs (shimano
> deore)?
Hub gears typically have /slightly/ more drag than deraileurs but
require /much/ less maintenance. Consequently for a non-racing urban
bike they make a lot of sense.
--
si...@jasmine.org.uk (Simon Brooke) http://www.jasmine.org.uk/~simon/
to err is human, to lisp divine
;; attributed to Kim Philby, oddly enough.
Mark van Gorkom
Not all Rollerbrakes are created equal: I have the kind that fits in
lieu of a disc brake, and had no problems with it, coming down Irish
hills with a fully laden recumbent. Can't fit Magura rim brakes, alas,
and had no end of problems with disc brakes.
Mark van Gorkom
Alex Rodriguez
>i am looking at a ridgeback switch at the moment.
>i was trying to get one with disk brakes but they're out of stock.
>the guy in the shop said hub brakes are better anyway.
No, the Nexus roller brakes are quite poor. For a rear brake it is not a
big deal. I would not ride a bike that had a front brake that is as poor as
the rear roller brakes are. I
>what about hub gears (nexus 8) vs regular derailleurs (shimano deore)?
The Nexus 8 is supposed to be better than the Nexus 7. I regualrly ride a
Nexus 7 and I can feel the difference between it and a derailleur bike. I
am aware of this, but I like have the drivertrain in the hub shell, less
maintenance. My commute is short, so it is not a big deal.
---------------
Alex
Alex Rodriguez
>
>
>Alex Rodriguez <ad...@columbia.edu> wrote in
>I agree about the disturbingly gradual buildup of stopping power in the
>shimano roller rear brake (no clutch there, unlike the front). My bike
>has cantilever bosses, so I kept the 7 spd hub but went back to v-brakes.
>And that's one less cable to disconnect to get the wheel off as well. The
>thing is packed with grease inside, and I think that contributed to the
>rather draggy feel. Maybe it was just due to shedding the weight, but I
>gained pretty much one gear on the hills of my commute after ditching it
>(I got the thing in the first place as it seemed a reasonable idea for
>all-weather commuting in a rainy climate).
Maybe Shimano will come out with a disk brake that will work with the Nexus
hub. That would be ideal. My front brake is a Avid disk brake and it works
well in all weather conditions.
----------------
Alex
Alex Rodriguez
cl...@xxxx-x.fsnet.co.uk says...
>Apply the front brake sufficiently and it will be able to :-)
>Seriously, the back brake shouldn't be doing much of the slowing anyway, so
>being a bit crap isn't much of a problem. Unless the front brake is also
>crap.
Quite true, and the reason I still have this set up. My front brake is an Avid
mechanical disk brake and it has plenty of stopping power in all conditions.
------------------
Alex
merryfreakinxmas
"Clive George" <cl...@xxxx-x.fsnet.co.uk> wrote in message
news:42c076a3$0$30811$ed26...@ptn-nntp-reader01.plus.net...
or long wheel based recumbents
Alex
Have you tried taking up the slack in the cable so the lever will not touch
the bar?
> cheers,
> clive
>
>
>
Alex Rodriguez
says...
>Alex
>Have you tried taking up the slack in the cable so the lever will not touch
>the bar?
Yes I have. The rear brake still can't lock up the rear wheel.
---------------
Alex
Sheldon Brown
>
>>i am looking at a ridgeback switch at the moment.
>>i was trying to get one with disk brakes but they're out of stock.
>>the guy in the shop said hub brakes are better anyway.
>
>
> No, the Nexus roller brakes are quite poor. For a rear brake it is not a
> big deal. I would not ride a bike that had a front brake that is as poor as
> the rear roller brakes are. I
>
_worse_ than the rear!
Shimano puts a slip clutch into their Rollerbrake front hubs as a
putative "safety" feature.
Seems a bit bizarre to me that a device that reduces braking power could
be considered a "safety
feature" though.
Some, but not all, Nexus front Rollerbrakes have annoying rattles in the
cable linkage.
>>what about hub gears (nexus 8) vs regular derailleurs (shimano deore)?
> The Nexus 8 is supposed to be better than the Nexus 7.
That's true, I own a Nexus 7 and two Nexus 8s. I just LOVE the Nexus 8,
commuted on one of them this morning...
(I left the Rollerbrakes off of all three of my Nexus bikes, don't need
a weak rear brake that weighs a pound and a quarter. I use rim brakes
on all three of these bikes.
http://sheldonbrown.org/raleigh-competition
http://sheldonbrown.org/raleigh-international
http://sheldonbrown.org/iro
Sheldon "Space Technology: Planetary Gears!" Brown
+------------------------------------------------+
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+------------------------------------------------+
Harris Cyclery, West Newton, Massachusetts
Phone 617-244-9772 FAX 617-244-1041
http://harriscyclery.com
Hard-to-find parts shipped Worldwide
http://captainbike.com http://sheldonbrown.com
pat.n...@iname.com
>Seems a bit bizarre to me that a device that reduces
>braking power could be considered a "safety feature" though.
I have no objection to the concept of modifying torque or preventing
skidding. ABS does both and is considered a safety feature.
I am only concerned about the implementation. ABS modifies torque if
vehicle motion exceeds wheel motion and operates low or high friction
surfaces. The Shimano system merely puts an upper limit on torque.
Shimano quotes ISO 4120 and DIN 79100-2. This requires a weight of 100
kg and a brake lever force of 100 N. I understand that the requirement
is to exceed 2.2 m/s^2 wet and 3.4 m/s^2 dry.
Shimano quotes a deceleration capability of 3 m/s^2 for the SG-8c20
rear hub. Magura claims rim brakes can achieve 4 m/s^2 and discs 8
m/s^2. It would be interesting to know the torque or deceleration
values for the Shimano front hub.
Ted Bennett
> Sheldon Brown wrote:
> >Seems a bit bizarre to me that a device that reduces
> >braking power could be considered a "safety feature" though.
>
> I have no objection to the concept of modifying torque or preventing
> skidding. ABS does both and is considered a safety feature.
As Sheldon would say, apples and locomotives. ABS has nothing at all to
do with the Shimano device, which arbitrarily cuts off braking with no
regard to the traction available, or whether or not the wheel is
skidding.
> I am only concerned about the implementation. ABS modifies torque if
> vehicle motion exceeds wheel motion and operates low or high friction
> surfaces. The Shimano system merely puts an upper limit on torque.
That's the problem. If the aim is to prevent skidding by limiting
torque, the geometry of the situation (position of the center of mass
relative to the front tire contact patch) as well as the total mass
being braked, must be considered. For very many riders, the
torque-limiting device enters into play before maximum braking is
achieved.
> Shimano quotes ISO 4120 and DIN 79100-2. This requires a weight of 100
> kg and a brake lever force of 100 N. I understand that the requirement
> is to exceed 2.2 m/s^2 wet and 3.4 m/s^2 dry.
>
> Shimano quotes a deceleration capability of 3 m/s^2 for the SG-8c20
> rear hub. Magura claims rim brakes can achieve 4 m/s^2 and discs 8
> m/s^2. It would be interesting to know the torque or deceleration
> values for the Shimano front hub.
An ordinary bike can achieve up to roughly 0.6g, or 5.8 m/s^2, before it
rotates on the contact patch. Any decent brake, whether rim or disc,
can do that. Where did you get those figures? They could not have been
generated by a rider on a bicycle.
--
Ted Bennett
Jasper Janssen
<p@honeydewbiggs{remove_melon}.tc> wrote:
>
>extremely carefully, I suppose ;-)
50-60% or more of the bikes on the road here have Sturmey, Sachs, or
Shimano 'roller' drum brakes on both wheels. Most of the rest are coaster
brake models. They work well enough for most people, although it's true
all drum brakes are fairly pathetic in absolute terms. I don't know,
though, if the Shimano roller front is much worse than a Sturmey Archer,
that could be a problem. OTOH, if it doesn't go out of adjustment as much
(and after a bit of wear, most Sturmeys are permanently out of
adjustment), it'd still be a net win.
Jasper
Simon Brooke
('jas...@jjanssen.org') wrote:
> On Mon, 27 Jun 2005 23:50:20 +0100, "Pete Biggs"
> <p@honeydewbiggs{remove_melon}.tc> wrote:
>>
>>Roller brakes can be used up front as well. It's one way to make you
>>ride extremely carefully, I suppose ;-)
>
> 50-60% or more of the bikes on the road here have Sturmey, Sachs, or
> Shimano 'roller' drum brakes on both wheels. Most of the rest are
> coaster brake models. They work well enough for most people
Where is 'here', and how high/steep are the local hills? I think this
sort of statement needs to be qualified in those terms. For values of
'here' which include much of southern Scotland, I think roller brakes
would be so inadequate as to be actively dangerous.
--
si...@jasmine.org.uk (Simon Brooke) http://www.jasmine.org.uk/~simon/
;; my other religion is Emacs
Mark van Gorkom
<si...@jasmine.org.uk> wrote:
>in message <ebaoe1dflq64si4ul...@4ax.com>, Jasper Janssen
>('jas...@jjanssen.org') wrote:
>
>> On Mon, 27 Jun 2005 23:50:20 +0100, "Pete Biggs"
>> <p@honeydewbiggs{remove_melon}.tc> wrote:
>>>
>>>Roller brakes can be used up front as well. It's one way to make you
>>>ride extremely carefully, I suppose ;-)
>>
>> 50-60% or more of the bikes on the road here have Sturmey, Sachs, or
>> Shimano 'roller' drum brakes on both wheels. Most of the rest are
>> coaster brake models. They work well enough for most people
>
>Where is 'here', and how high/steep are the local hills? I think this
>sort of statement needs to be qualified in those terms. For values of
>'here' which include much of southern Scotland, I think roller brakes
>would be so inadequate as to be actively dangerous.
Not all rollerbrakes are created equal; I have the kind that fit on a
disc brake fork, and had no problems going down some rather steep
hills in Ireland (on a lowracer with a fair amount of luggage).
Best brakes, IMHO, are Magura HS33, but I have no bikes that I can fit
them on. Would like to try the new I-brakes, but that's anotther wheel
rebuild.
Mark van Gorkom.
Jasper Janssen
>('jas...@jjanssen.org') wrote:
>>
>> 50-60% or more of the bikes on the road here have Sturmey, Sachs, or
>> Shimano 'roller' drum brakes on both wheels. Most of the rest are
>> coaster brake models. They work well enough for most people
>
>Where is 'here', and how high/steep are the local hills? I think this
>sort of statement needs to be qualified in those terms. For values of
>'here' which include much of southern Scotland, I think roller brakes
>would be so inadequate as to be actively dangerous.
'Here' would be the Netherlands. Hills? What are those? We've got
humpbacked bridges. That's about it. At least, while there are some hills
in the country, those would not usually be the place where these bikes go
in modern times, and they're fairly tame by any serious hillfolk's
standards anyway. Still, though, back in the 50s, 60s, and 70s there were
plenty of people riding these threespeeds, and even singlespeed
coaster-brakes, to the Ardennes mountains or even the Alps.
Jasper
Dan Gregory
> Still, though, back in the 50s, 60s, and 70s there were
> plenty of people riding these threespeeds, and even singlespeed
> coaster-brakes, to the Ardennes mountains or even the Alps.
Yes, I remember my first trip round France in 1956. Somewhere between
Dijon & Lyon there was a large grassy bank next to the road and on it
were dozens of Dutch and German cylists (all teenagers like me) and they
were all on "sit up & beg" single speed bikes.
I met some on the Tourmalet too!
All the best
Dan Gregory