disk brakes: can they be made safe (now) by customers?
SantaCruzCity rider
about popouts. However I'm not sure of the current solutions.
Apparently there can be problems even with 'lawyer lips' as a
solution. Bolts I guess are foolproof.(?)
I'm trying to decide whether or not to get disk brakes. I'm a student
at UC-Santa Cruz, and this will be the first winter (VERY rainy
season) that I commute by bicycle. Relevancy being: it is a very
long, at many points very steep, downhill from campus to home (about 2
miles downhill). And this downhill will be done in rain the majority
of days, once winter starts. So I am very interested in brakes that
work better in the rain (thus keeping me safer). BUT, if I'm going to
be in more danger from popouts it doesn't make sense to spend lots of
$$s (which I'm scarce on) on something that doesn't increase my
security.
You all have strong opinions and lots of technical knowledge, so I'm
hoping for advice- my thanks in advance for all advice/opinions
offered :-)
Werehatrack
(SantaCruzCity rider) may have said:
>I've read a lot of the posts in this thread; enough to get concerned
>about popouts. ... So I am very interested in brakes that
>work better in the rain (thus keeping me safer). BUT, if I'm going to
>be in more danger from popouts it doesn't make sense to spend lots of
>$$s (which I'm scarce on) on something that doesn't increase my
>security.
Just my opinion: With lawyer lips and some attention to making sure
your skewer is properly adjusted, I doubt that you would be able to
get the wheel to eject in the type of riding you describe, even if you
tried really hard. But, if you're the least bit worried, get a solid
axle, eschew the skewer, and don't worry about the problem at all.
From where I'm sitting, I firmly believe that the severity of the risk
can be reduced to an acceptable level by either of those means.
Bearing in mind that the number of reported incidents of wheel
ejection thus far is apparently fairly small, it does not appear that
the risk of ejection is great in any case. I'd expect the risk of
brake ineffectiveness due to water to be the greater hazard; as such,
using the disc brake seems to be the prudent course.
--
My email address is antispammed;
pull WEEDS if replying via e-mail.
Yes, I have a killfile. If I don't respond to something,
it's also possible that I'm busy.
Mike S.
> >about popouts. ... So I am very interested in brakes that
> >work better in the rain (thus keeping me safer). BUT, if I'm going to
> >be in more danger from popouts it doesn't make sense to spend lots of
> >$$s (which I'm scarce on) on something that doesn't increase my
> >security.
>
> Just my opinion: With lawyer lips and some attention to making sure
> your skewer is properly adjusted, I doubt that you would be able to
> get the wheel to eject in the type of riding you describe, even if you
> tried really hard. But, if you're the least bit worried, get a solid
> axle, eschew the skewer, and don't worry about the problem at all.
> From where I'm sitting, I firmly believe that the severity of the risk
> can be reduced to an acceptable level by either of those means.
>
> Bearing in mind that the number of reported incidents of wheel
> ejection thus far is apparently fairly small, it does not appear that
> the risk of ejection is great in any case. I'd expect the risk of
> brake ineffectiveness due to water to be the greater hazard; as such,
> using the disc brake seems to be the prudent course.
>
I'll second the motion. I've ridden discs on my mtn bike for several years
and have never heard of, seen, or had a disc equipped wheel eject from my
dropouts. Mtn biking is going to be a lot harder on the brakes than merely
commuting down a paved road in the rain.
If you're really stressed about it, get yourself a bolt-on front axle.
Between the bolt-on axle and the lawyer lips, you should be bulletproof.
If you're even more stressed than that, don't buy discs. Rim brakes have
been doing OK in the road world (and everywhere else for that matter!) for a
VERY long time.
Mike
S. Anderson
news:afjrov0nb504sfsrv...@4ax.com...
>
> Just my opinion: With lawyer lips and some attention to making sure
> your skewer is properly adjusted, I doubt that you would be able to
> get the wheel to eject in the type of riding you describe, even if you
> tried really hard.
I'd agree. Emergency rooms aren't filled with people with busted bones as a
result of wheel ejection. The problem is real, but with regular checks for
tightness (like, every ride if you're nervous) I'm sure the benefits
outweigh the probability of ejection.
Cheers,
Scott..
Tim McNamara
> I've read a lot of the posts in this thread; enough to get concerned
> about popouts. However I'm not sure of the current solutions.
"Solutions" are scarce on the ground. You're right to be concerned,
IMHO, but than I am one of the people that thinks there is a problem
and that it's significant. This topic has been hashed, rehashed and
rerehashed in this newsgroup. Suffice to say, the evidence is being
gathered and the magnitude of the problem is becoming better
quantified. Once that information is collected, thepath forward will
be clearer.
None of which helps your decision today! Now, speaking personally,
I've never felt a need for disk brakes on a bike whether riding on the
road or trails, mountain bike racing, 'cross racing, road racing,
etc. I avoid riding when the trails are muddy because it's
destructive and I don't want the trails closed because of erosion
damage.
I do ride in the rain, and find that with the polished aluminum rims I
use and Mathauser or KoolStop salmon brake pads, my wet-weather
stopping is fine. However, with rims with anodized sidewalls,
wet-weather stopping is abysmal until some of the anodizing is
scrubbed off the rims. Rims with machined sides address that problem
(although there are trade-offs).
If it was my decision, given the conditions you mention, I'd pick rim
brakes with a carefully chosen combination of rim and pads. There are
several reasons, including investment- why spend money for a theft
magnet that's going to be sitting out in the rain all day? For
commuting, ride a cheap bike.
Matt O'Toole
"S. Anderson" <scott.a...@zsympaticoz.ca> wrote in message
news:Xfkjb.3577$Z_2.3...@news20.bellglobal.com...
I agree too. Just don't get lax about things like tightening quick releases.
Accidents happen when people put off tightening the QR properly until later, or
leave their brakes undone after fixing a flat because they ran off to answer the
phone. Whenever you put the wheel in the dropout, *always* make sure it's
tightened properly. And never leave a bike with its brakes undone either.
One neat thing about disks is that you can't leave them undone! (They just slip
in and out with nothing to undo.) So by going to disks you've made one problem
worse, but you've eliminated another. :-)
Matt O.
Matt O'Toole
"Tim McNamara" <tim...@bitstream.net> wrote in message
news:m2ad82m...@localhost.bitstream.net...
> Now, speaking personally,
> I've never felt a need for disk brakes on a bike whether riding on the
> road or trails, mountain bike racing, 'cross racing, road racing,
> etc. I avoid riding when the trails are muddy because it's
> destructive and I don't want the trails closed because of erosion
> damage.
>
> I do ride in the rain, and find that with the polished aluminum rims I
> use and Mathauser or KoolStop salmon brake pads, my wet-weather
> stopping is fine. However, with rims with anodized sidewalls,
> wet-weather stopping is abysmal until some of the anodizing is
> scrubbed off the rims. Rims with machined sides address that problem
> (although there are trade-offs).
I agree with this too. I've never felt the need for disks, no matter what the
weather and trail conditions. They would be nice for snow, where rims get iced
up, but few people ride in those conditions regularly. However, they do make
sense for mountain bikers who ride in mud a lot. This can wear out rims in a
jiffy. I've talked to mountain bikers from the UK and BC who used to go through
rims every few months. In the long run, disks are cheaper in these conditions,
as well as safer (worn rims can collapse). Also, disks give more precise
control in wet conditions.
> If it was my decision, given the conditions you mention, I'd pick rim
> brakes with a carefully chosen combination of rim and pads. There are
> several reasons, including investment- why spend money for a theft
> magnet that's going to be sitting out in the rain all day? For
> commuting, ride a cheap bike.
Good advice. Santa Cruz definately has *that* element...
Matt O.
Sheldon Brown
> I've read a lot of the posts in this thread; enough to get concerned
> about popouts. However I'm not sure of the current solutions.
> Apparently there can be problems even with 'lawyer lips' as a
> solution. Bolts I guess are foolproof.(?)
>
> I'm trying to decide whether or not to get disk brakes. I'm a student
> at UC-Santa Cruz,
Oooh, so is my daughter Tova! I hear it's really nice out there, but
haven't yet visited.
> and this will be the first winter (VERY rainy season)
Are you telling me it _rains_ in California?
> that I commute by bicycle. Relevancy being: it is a very
> long, at many points very steep, downhill from campus to home (about 2
> miles downhill). And this downhill will be done in rain the majority
> of days, once winter starts. So I am very interested in brakes that
> work better in the rain (thus keeping me safer). BUT, if I'm going to
> be in more danger from popouts it doesn't make sense to spend lots of
> $$s (which I'm scarce on) on something that doesn't increase my
> security.
The wheel popping problem does evidently occur, but is quite uncommon.
It is my impression that it mainly affects folks who ride rugged, bumpy
trails.
I believe you'll be safe if you check the tightness of your QR skewer
regularly, and keep it good and tight.
In addition, I would advise avoiding the inferior skewers that have
exposed cams. Get a Shimano or Campagnolo skewer with an internal cam
and don't worry.
Sheldon "Exposed Cams Not Good" Brown
+-------------------------------------------------------------+
| Give a man a fire, and he will stay warm for a day. |
| Set a man on fire, he stays warm for the rest of his life. |
+-------------------------------------------------------------+
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
Prometheus
It rains in NORTHERN california.
Santa Cruz is universally considered the most bike-friendly town in the US.
if rain was such a problem, people wouldn't ride as much. you're trying to
justify having cool disc brakes (not that I blame, because I looked into
this myself, and Pittsburgh is MUCH more rainy than Santa Cruz).
Mike, Los Angeles native.
Mechanical Engineering 2006, Carnegie Mellon University
Remove nospam to reply.
--On Wednesday, October 15, 2003 11:50 PM -0400 Sheldon Brown
Simon Brooke
> I'm trying to decide whether or not to get disk brakes. I'm a student
> at UC-Santa Cruz, and this will be the first winter (VERY rainy
> season) that I commute by bicycle.
According to <URL: http://ggweather.com/ca_climate/rain_mean.htm >
Santa Cruz sees an average of 30.37 inches of rain annually, with a
wettest month of January with 6.79 inches. Here in the West of
Scotland we get three times that much, with up to 9.4 inches falling
on a single day.
See
<URL: http://www.met-office.gov.uk/climate/uk/location/scotland/#rainfall >
Disk brakes are not required for normal riding here. Indeed, you have
to be doing pretty extreme things for them to be useful. And they have
a lot of downside in terms of weight and complexity. As I've said, my
favourite bike does have disks, but it isn't an every-day bike for use
in normal conditions - I wouldn't even consider it for use on the road.
--
si...@jasmine.org.uk (Simon Brooke) http://www.jasmine.org.uk/~simon/
Hobbit ringleader gives Sauron One in the Eye.
Simon Brooke
> In addition, I would advise avoiding the inferior skewers that have
> exposed cams. Get a Shimano or Campagnolo skewer with an internal cam
> and don't worry.
Why is this? Is there a mechanical reason for choosing skewers with
shrouded cams, or do you simply find these brands to be more reliable?
--
si...@jasmine.org.uk (Simon Brooke) http://www.jasmine.org.uk/~simon/
my other car is #<Subr-Car: #5d480>
;; This joke is not funny in emacs.
Michael
> In addition, I would advise avoiding the inferior skewers that have
> exposed cams. Get a Shimano or Campagnolo skewer with an internal cam
> and don't worry.
Interesting. I'd like more specific info. By exposed cam, do you
mean the cam is built into the lever (that you push on to close the
skewer)? I think my Salsa skewers are like that.
Why would an exposed cam be inferior for this application? Are you
implying that it doesn't hold as well, or is the fact that it's
exposed relevant (perhaps dirt may accumulate and reduce claming
effectiveness)?
Thanks,
Michael
jim beam
riding them on a mountain bike on some "interesting" terrain for nearly
two years. never loosened and /definitely/ never ejected. and i've
never seen it or even heard of it from any of my friends or friends of
friends. in the absence of hard statistical evidence to the contrary,
i'm going to let my personal experience guide me in this one!
it may also be interesting to note that the individual whose website
seems to be provoking the biggest debate on this subject has some
pictures of their equipment on their site, including this:
http://www.ne.jp/asahi/julesandjames/home/disk_and_quick_release/stratos.jpg
this clearly shows the deployment of twisted spokes on a front disk
braked wheel! twisted spoking is very unsatisfactory for torque
transfer. such a conceptual flaw does not inspire confidence in other
arguments.
jb
Sheldon Brown
>>In addition, I would advise avoiding the inferior skewers that have
>>exposed cams. Get a Shimano or Campagnolo skewer with an internal cam
>>and don't worry.
Michael Press asked:
> Interesting. I'd like more specific info. By exposed cam, do you
> mean the cam is built into the lever (that you push on to close the
> skewer)?
The cam is always built into the lever, but the good skewers have a
smaller cam, completely hidden from view because it's all inside the
dome-like housing.
The bad skewers have a larger diameter cam, actually usually split into
two parallel sections. There is no housing, the cam presses onto a
curved washer which in turn presses on to the part that grips the left
side of the fork.
> I think my Salsa skewers are like that.
Yes, I believe they are.
> Why would an exposed cam be inferior for this application? Are you
> implying that it doesn't hold as well, or is the fact that it's
> exposed relevant (perhaps dirt may accumulate and reduce claming
> effectiveness)?
When you close the skewer, your hand strength is accomplishing two
things: It's applying a clamping force to the skewer, and it's
overcoming the mechanical friction of the mechanism.
The exposed cam can not be kept clean and well lubricated as the
shielded one can.
In addition, the exposed cam is a larger diameter, so the friction is
acting on a longer moment arm (the radius of the cam.)
The result is very much less clamping force for a given amount of hand
force on the lever.
The best skewers also have a better shape to the cam, so it goes slighly
_past_ the tightest position as it locks, making it much less likely to
loosen up.
In my experience, Shimano skewers are the best, closely followed by
Campagnolo.
The exposed-cam skewers are generally OK for vertical dropouts in back,
and for forks with "lawyer lips", but should not be relied on with
horizontal dropouts or plain forks. Recent reports also suggest that
they're not safe with typical front disk brakes.
I do plan to write an article on this when I find the time...
Sheldon "Inside Man" Brown
+---------------------------------------------------------+
| It is good to learn from your mistakes; |
| It is better to learn from the mistakes of others. |
+---------------------------------------------------------+
Matt O'Toole
"Sheldon Brown" <capt...@sheldonbrown.com> wrote in message
news:3F8EB9A9...@sheldonbrown.com...
Don't forget there's more raw leverage with the smaller cam. Leverage equals
length of the lever times the radius of the cam, and Shimano/Campy cams are half
the size, or less.
> The best skewers also have a better shape to the cam, so it goes slighly
> _past_ the tightest position as it locks, making it much less likely to
> loosen up.
>
> In my experience, Shimano skewers are the best, closely followed by
> Campagnolo.
>
> The exposed-cam skewers are generally OK for vertical dropouts in back,
> and for forks with "lawyer lips", but should not be relied on with
> horizontal dropouts or plain forks. Recent reports also suggest that
> they're not safe with typical front disk brakes.
>
> I do plan to write an article on this when I find the time...
Several years ago, Mountain Bike Action tested the clamping force of all the
popular skewers. This was back when light weight was "in," and everyone and his
brother was making Ti skewers with purple anodized levers. Campy and Shimano
skewers had the highest clamping force by far, with the next best being Salsa
steel units. Some of the more popular ones, particularly the best-selling
Ringle, were a joke. Since then, the designs have changed a lot (thankfully),
but Shimano and Campy are still best, for all the reasons Sheldon just
mentioned.
Matt O.
Carl Fogel
> adventur...@yahoo.com (SantaCruzCity rider) writes:
>
> Here in the West of
> Scotland we get three times that much, with up to 9.4 inches falling
> on a single day.
>
Dear Simon,
Dear God, I hope that's a typo!
Here in the South of Colorado, we got under 3 inches
in 2002, but average (pardon my boasting) as much as
12-14 inches every year.
After forty years of careful consideration, I purchased
a rain coat from Performance. Quite handsome and useful
as a windbreaker for cold riding, but I can't really say
whether it works in the rain.
I suppose that I could step into the shower and test it . . .
Here I'm counting the tarantulas that I see on my
daily ride--they're migrating across the roads. What
is the equivalent in Scotland? Toads? Salamanders?
Or perhaps cats-and-dogs?
Carl Fogel
Traveller v.116
news:8bbde8fc.03101...@posting.google.com:
Try horned toads up in the Texas panhandle. Self-mobile tire spikes.
Or armadillos. Moving speed bumps.
And the occasional rattlesnake.
It sure was fun learning to dodge all those critters when I was growing up
there. But I think I'de prefer the big hairy spiders.
g.daniels
several times sans brakes due to wetness visavee imimentnt death.
this discussion-there were several hundred other riders with the same
glandular problems-went on for 6-7 months-with the upshot being thait
was too much off a royal pain in the butt to bother with
leading to several discussions of wet brake pads of a fish like
colouupgrades with a different clamp system(see sheldon brown
homebrews)
and what i did-clean the rim and pads with cut strips from old sweat
socks using the knit insides wet with iso/cho via the superduper. b4
riding or
eeeeeeeeeoooowwww during riding.
now thersa revolutionary thought.
if one can't stop. stop and clean the areas.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
revolutionary thinking cures
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Carl Fogel
[snip]
> it may also be interesting to note that the individual whose website
> seems to be provoking the biggest debate on this subject has some
> pictures of their equipment on their site, including this:
>
> http://www.ne.jp/asahi/julesandjames/home/disk_and_quick_release/stratos.jpg
>
> this clearly shows the deployment of twisted spokes on a front disk
> braked wheel! twisted spoking is very unsatisfactory for torque
> transfer. such a conceptual flaw does not inspire confidence in other
> arguments.
Dear Jim,
I hadn't a clue what you meant by "twisted spokes," so I
looked at the link that you provided and was delighted--it's
as good as stumbling across a platypus for the first time.
Curious, I searched for what Jobst Brandt had to say about
what looks like the chain-link-fence school of wheel design
and found a thread from 1995 that included these comments
on what might be wrong with bending one spoke around another:
>> The big feature is that you cannot stress relieve these bends and if
>> you break a spoke you lose two. It is difficult to build and much
>> harder to replace a spoke, something that is much more likely to be
>> necessary with this pattern.
There may be other drawbacks, but those are a pretty good start.
I'm not sure about "torque transfer"--all that I remember from
my efforts to pretend that I understood "The Bicycle Wheel" is
that Jobst found that the torque on the rear wheel didn't produce
much wind-up between the hub and the rim, but I may not be
thinking of the right terms and perhaps a mountain bike front
wheel endures more torque.
In any case, I can't recall any of these entwined spokes on
off-road motorcycles, but I'm going to ask around. If there
are benefits, then I'd expect the motocross crowd to be
cross-breeding their spokes with climbing ivy.
Thanks again for that fascinating picture.
Carl Fogel
Simon Brooke
> Simon Brooke <si...@jasmine.org.uk> wrote in message news:<87zng14...@gododdin.internal.jasmine.org.uk>...
> >
> > Here in the West of
> > Scotland we get three times that much, with up to 9.4 inches falling
> > on a single day.
>
> Dear God, I hope that's a typo!
No, it's for real. Mind you, further north it's worse, around Fort
William it averages 118 inches and 250 days of rain each year.
> Here in the South of Colorado, we got under 3 inches
> in 2002, but average (pardon my boasting) as much as
> 12-14 inches every year.
>
> Here I'm counting the tarantulas that I see on my
> daily ride--they're migrating across the roads. What
> is the equivalent in Scotland? Toads? Salamanders?
Toads, certainly - masses of them in the spring. No salamanders, too
cold.
--
si...@jasmine.org.uk (Simon Brooke) http://www.jasmine.org.uk/~simon/
;; gif ye hes forget our auld plane Scottis quhilk your mother lerit you,
;; in tymes cuming I sall wryte to you my mind in Latin, for I am nocht
;; acquyntit with your Southeron
;; Letter frae Ninian Winyet tae John Knox datit 27t October 1563
James Annan
>
> No, it's for real. Mind you, further north it's worse, around Fort
> William it averages 118 inches and 250 days of rain each year.
But it's still not really all that wet. Your 9.4 inches (238mm) was a
one-day record from decades ago, but here in Japan we have days like
that every year.
Of course we all know it's the weather and hills that stops people from
riding bikes.....sure....
James
James Annan
>
> http://www.ne.jp/asahi/julesandjames/home/disk_and_quick_release/stratos.jpg
>
>
> this clearly shows the deployment of twisted spokes on a front disk
> braked wheel! twisted spoking is very unsatisfactory for torque
> transfer. such a conceptual flaw does not inspire confidence in other
> arguments.
Oh you nitwit. Why didn't you think to ask why the spokes are twisted
before jumping to conclusions? It's already been explained on usenet if
you know how to use Google.
I presume you cannot even think of any similarly half-assed comments on
the 'other arguments', however low your confidence in them is, otherwise
you would no doubt have enlightened us all.
James
Simon Brooke
> I'm not sure about "torque transfer"--all that I remember from
> my efforts to pretend that I understood "The Bicycle Wheel" is
> that Jobst found that the torque on the rear wheel didn't produce
> much wind-up between the hub and the rim, but I may not be
> thinking of the right terms and perhaps a mountain bike front
> wheel endures more torque.
In any hub braked wheel, the brake exerts a torque on the hub which
must be transferred to the rim by the spokes. Since the deceleration
of which good brakes are capable is greater than the acceleration
which most people can put into a bike, the torque forces in a hub
braked wheel must be greater than those in a normal rear wheel, and
the spoke pattern must be capable of transferring this torque to the
rim (and thus to the tyre and thus to the contact patch).
Benjamin Weiner
> SantaCruzCity rider wrote:
> > I'm trying to decide whether or not to get disk brakes. I'm a student
> > at UC-Santa Cruz,
> Oooh, so is my daughter Tova! I hear it's really nice out there, but
> haven't yet visited.
> > and this will be the first winter (VERY rainy season)
> Are you telling me it _rains_ in California?
It is nice. It does rain in winter, but the pattern isn't like East
Coast rain. Rather, it can rain like hell for a few days, occasionally
several inches per day, then be nice again. Number of rainy days depends
on whether it's an El Nino winter or not.
> > that I commute by bicycle. Relevancy being: it is a very
> > long, at many points very steep, downhill from campus to home (about 2
> > miles downhill). And this downhill will be done in rain the majority
> > of days, once winter starts. So I am very interested in brakes that
> > work better in the rain (thus keeping me safer). BUT, if I'm going to
> > be in more danger from popouts it doesn't make sense to spend lots of
> > $$s (which I'm scarce on) on something that doesn't increase my
> > security.
Get discs if you want, but you don't need them to ride this descent
safely. Decent brake pads are sufficient. Do get full fenders if you're
interested in commuting comfort.
jim beam
have fun over there. there's no need to be rude on this forum.
regarding the real issue, your assertion that disks are fatally flawed,
your web page has an interesting analysis. however, i believe it
too simplistic to support the radical hypothesis you are looking to
promote.
while theoretically, the rough outline of your analysis seems in order
[certain assumptions and omissions aside] the factor that you [and the
analysis in http://www.engr.ukans.edu/%7Ektl/bicycle/QRReport1.pdf] fail
to take account of, is the significant influence the use of common fork
materials have on the pull-out force. [the report only addresses
material's effect on clamp closing force, not pull-out].
as you have doubtless observed, all modern quick-release hubs have
serrated clamping faces on their spindles. these serrations get
_embedded_ into the fork material, particularly over time. this is
especially evident with softer fork materials like aluminum & magnesium
alloys. therefore, from a shear mode viewpoint, the spindle is held in
place not just by the clamping friction, but by the intimate placement
of serration with indentation. the shear stress necessary to disengage,
[i.e. shear through] approx 100mm^2 of enmeshed material [from my
measurement of an ultegra hub - which happens to be on my desk as i
write] is going to be an order of magnitude more than the force you are
demonstrating. the serrations are no less important to structural
integrity than the threads on the clamping bolt itself.
this is not to criticise the concern behind your analysis, but i believe
you need to broaden some of your considerations to reflect practical
reality.
jb
Tim McNamara
<snip>
> as you have doubtless observed, all modern quick-release hubs have
> serrated clamping faces on their spindles. these serrations get
> _embedded_ into the fork material, particularly over time.
<snip>
Jeez, jb, we've already *had* that argument and it's been shown that
this is not correct. Nor is it correct that all QRs have serrated
faces. Yadda yadda yadda. Refresh your memory with the several
hundred prior posts arguing that Annan is all wet for any one of three
dozen reasons, if you must.
At this point it's about independent corroboration or refutation, and
about data gathering on incidence. The ball is in the industry's
court and the rest of us are just waiting... and double checking those
QRs. FWIW there is rather grudging admission from industry quarters
that Annan's analysis is indeed fundamentally correct- that there is
an ejection force and that this force is of high magnitude.
In the meantime, watch the video Annan has of a front wheel being
ejected from a fork. It ain't gentle and it ain't pretty. Especially
for the guy riding the bike at the time.
jim beam
>>as you have doubtless observed, all modern quick-release hubs have
>>serrated clamping faces on their spindles. these serrations get
>>_embedded_ into the fork material, particularly over time.
>
> <snip>
>
> Jeez, jb, we've already *had* that argument and it's been shown that
> this is not correct. Nor is it correct that all QRs have serrated
> faces. Yadda yadda yadda. Refresh your memory with the several
> hundred prior posts arguing that Annan is all wet for any one of three
> dozen reasons, if you must.
i'm open to persuasion! i'm merely commenting based on what i know and
my personal experience. all of /my/ [disk] hubs are deeply serrated &
all of /my/ forks are correspondingly deeply indented. my comments are
naturally based on that! if someone can show me the inside surface of a
fork that has been serrated, yet still ejected and it does not show
evidence of shear, then i'll show you a q.r. that was not fastened
properly. period.
> At this point it's about independent corroboration or refutation, and
> about data gathering on incidence. The ball is in the industry's
> court and the rest of us are just waiting... and double checking those
> QRs. FWIW there is rather grudging admission from industry quarters
> that Annan's analysis is indeed fundamentally correct- that there is
> an ejection force and that this force is of high magnitude.
you're right about the ball being in industry's court, to a point, but
why does industry have to prove anything when there's no evidence that
this is actually an issue seen in practice? as mentioned, i have asked
around friends & friends of friends to see if anyone has ever heard of
this kind of problem. negative. i've even asked in 3 different lbs's
[this theory is interesting enough for me to actually bother to do
that!] - but again, negative. is there a massive conspiracy to keep
this thing hushed? i really don't think so.
if there /is/ any issue, sheldon hit the nail on the head with his q.r.
comment. the only axle q.r. i've ever used that has exhibited any
loosening [on a rear non-disk axle] is one of those external cam types.
and i returned it to the shop immediately. awful. the external cam i
have on my seat post clamp, when it gets full of mud? impossible to
close! but my shimano [and campy road] skewers are absolutely
fundamentally superb. as sheldon says, they have a much higher leverage
and therefore superior clamping abilities. and they keep clean. as i
said before, i've ridden some pretty whacky terrain this last couple of
years, with disk brakes, and i've never had a [shimano] q.r. loosen.
even slightly. so, if james wants to nail people up, let it be boutique
q.r. manufacturers - there's nothing wrong with the brake/fork concept
in my opinion.
regarding force, even with only 25mm^2 of serration engagement and a
shear stress of only 200N/mm^2 for the fork material, that's still
5,000N necessary to cause material yield. that's grossly
over-simplified, but you get the idea that it isn't simply a case of
saying that 1825N is a big number - it isn't!
> In the meantime, watch the video Annan has of a front wheel being
> ejected from a fork. It ain't gentle and it ain't pretty. Especially
> for the guy riding the bike at the time.
great vid. so why can't i replicate it? i've got basically the same
gear. i'm a fully paid up member of the o.t.b. club, busted bones,
eggshell helmets, the works, but never from axle ejection! personally,
i'd be more worried about fatigue in my frame welds.
j
James Annan
> i'm open to persuasion! i'm merely commenting based on what i know and
> my personal experience. all of /my/ [disk] hubs are deeply serrated &
> all of /my/ forks are correspondingly deeply indented. my comments are
> naturally based on that! if someone can show me the inside surface of a
> fork that has been serrated, yet still ejected and it does not show
> evidence of shear, then i'll show you a q.r. that was not fastened
> properly. period.
I think you presume too much about the ubiquity and uniformity of
performance of the knurling on the hub locknuts. Sure, it will be one
factor that may differ between components, but the pull testing cited on
the web site was intended to be a realistic test, and there are plenty
of others who have seen hub movement and QRs unscrewing with a range of
equipment used.
> is there a massive conspiracy to keep
> this thing hushed? i really don't think so.
Try asking any major manufacturer for some public comment on the issue.
> there's nothing wrong with the brake/fork concept
> in my opinion.
Well, you are entitled to your opinion, but even most of those who still
deny that there is a significant problem in practice, can see that an
ejection force well in excess of the design standard for wheel retention
is an obvious design flaw that should be corrected.
James
jim beam
James Annan wrote:
> jim beam wrote:
>
>> i'm open to persuasion! i'm merely commenting based on what i know
>> and my personal experience. all of /my/ [disk] hubs are deeply
>> serrated & all of /my/ forks are correspondingly deeply indented. my
>> comments are naturally based on that! if someone can show me the
>> inside surface of a fork that has been serrated, yet still ejected and
>> it does not show evidence of shear, then i'll show you a q.r. that was
>> not fastened properly. period.
>
>
> I think you presume too much about the ubiquity and uniformity of
> performance of the knurling on the hub locknuts. Sure, it will be one
> factor that may differ between components, but the pull testing cited on
> the web site was intended to be a realistic test, and there are plenty
> of others who have seen hub movement and QRs unscrewing with a range of
> equipment used.
you probably have a point about different manufacturers quality
criteria, but regarding the pull-out test cited, despite best
intentions, the one thing it does /not/ do is compare the effect of
pull-out for different materials. it just uses a single test steel
fork. different fork materials are compared for clamping only. that's
a vital variable to have missed for the reasons i mentioned earlier.
as an analogy, consider the wire ropes used in an elevator. there are
different anchoring methods, but a common one is to open the end of the
rope into its constituent ropelets, insert a wedge, then embed it into a
lead or white metal lined cone on the elevator's frame. embedding the
rope into this soft metal is the key factor in satisfactory anchoring.
if you tried doing the same thing with hard steel, it would just slip.
if you think about it, bike brake and gear cables employ the the same
principle on their cable clamps too - one hard face to apply pressure,
one soft alloy face for anchoring.
>> is there a massive conspiracy to keep this thing hushed? i really
>> don't think so.
>
> Try asking any major manufacturer for some public comment on the issue.
with respect, could your style have anything to do with that? your
approach is very combative.
> even most of those who still
> deny that there is a significant problem in practice, can see that an
> ejection force well in excess of the design standard
well, this all comes down to "the design standard". maybe you can show
a contrary example, but reality is that manufacturers, by and large,
/have/ to produce product that works! if there was a "design standard"
for chains and it was 1/8" width, should we all have to stick to riding
around on 6-speeds? clearly not! just because "design standard" is
only 500N, doesn't mean that anyone is fool enough to design down to
that level just because the "standard" says so.
best
jb
James Annan
> you probably have a point about different manufacturers quality
> criteria, but regarding the pull-out test cited, despite best
> intentions, the one thing it does /not/ do is compare the effect of
> pull-out for different materials. it just uses a single test steel
> fork. different fork materials are compared for clamping only. that's
> a vital variable to have missed for the reasons i mentioned earlier.
So would it be fine if this problem only happened to steel forks?
Regardless, there's plenty of observations of it happening to a wide
range of common equipment in normal use. Certainly not all of the
stories relate to unusually hard fork ends, although I have not
checked their metallurgy in detail and see no purpose in doing so.
Even where it hasn't yet failed, the design is still a bad one.
> >> is there a massive conspiracy to keep this thing hushed? i really
> >> don't think so.
> >
> > Try asking any major manufacturer for some public comment on the issue.
>
> with respect, could your style have anything to do with that? your
> approach is very combative.
I mean you, jim beam, could try asking. After all, it's interested you
sufficiently to post a few messages here, it wouldn't take any more
effort to email your favourite manufacturers. I didn't start off so
'combative', but so far they've come up with nothing more than evasion
and incompetence. The problem was described 6 months ago and all the
nit-picking, hand-wringing and dodging since then isn't actually
solving anything.
> well, this all comes down to "the design standard". maybe you can show
> a contrary example, but reality is that manufacturers, by and large,
> /have/ to produce product that works!
Well, they have a product in which a complete failure is rare, but it
still fails, in a manner which the manufacturers have always
previously insisted in impossible in principle. A partial failure (of
axle movement and some QR loosening) seems quite common in some
circles, and can be reproduced at will, even if it is usually caught
before wheel ejection.
James
Carl Fogel
Dear James,
Perhaps you would enlighten this nit-wit?
What's the theory behind twisting pairs of spokes
around each other?
Google offered me over 700 hits, but I stumbled over
no explanations, beyond an apparently serious one about
it being a way to make too-long spokes work on a rim
when the right parts weren't available.
A friend who's been a Honda mechanic for thirty years
shook his head and said that he wasn't aware of any
off-road motorcycles using twisted spokes.
So I'm stumped and hoping for an explanation.
Thanks,
Carl Fogel
James Annan
> Perhaps you would enlighten this nit-wit?
>
> What's the theory behind twisting pairs of spokes
> around each other?
>
> Google offered me over 700 hits, but I stumbled over
> no explanations, beyond an apparently serious one about
> it being a way to make too-long spokes work on a rim
> when the right parts weren't available.
Looks like you found my post then. The original rim was buckled during a
remote week-long MTB race (Transrockies).
James
jim beam
> stories relate to unusually hard fork ends, although I have not
> checked their metallurgy in detail and see no purpose in doing so.
we /definitely/ disagree on this point. honestly, how can you expect to
be taken seriously when approaching a manufacturer if you're not
prepared to consider all of the relevant design elements? i admire your
passion and creativeness james, but you've /got/ to look at the big
picture in order to know which direction to move.
<snip>
> The problem was described 6 months ago and all the
> nit-picking, hand-wringing and dodging since then isn't actually
> solving anything.
isn't solving what? habeus corpus.
jb.
James Annan
> honestly, how can you expect to
> be taken seriously when approaching a manufacturer if you're not
> prepared to consider all of the relevant design elements?
I think that it's obvious enough to anyone with any engineering nous
that it is ridiculous to have to rely on the integrity of a
sub-millimetre depth of interlocking of the surface roughness of
locknuts and (painted) fork end against a massive force trying to pull
the wheel out, in an environment where there is likely to be mud. It's
not even worth the time I wasted typing that sentence.
> i admire your
> passion and creativeness james, but you've /got/ to look at the big
> picture in order to know which direction to move.
>
> <snip>
>
> > The problem was described 6 months ago and all the
> > nit-picking, hand-wringing and dodging since then isn't actually
> > solving anything.
>
> isn't solving what? habeus corpus.
If you are claiming that the various observations of the problem
listed and linked from my web page are all invention, mistaken or
otherwise incorrect then IMO it's you who is not looking at 'the big
picture', or indeed any picture at all. It's not as if there is
anything particularly controversial or difficult to understand about
the problem, and the various contrived dog-ate-my-homework excuses
that have been supplied as alternative explanations smack of
desperation.
So, what did the manufacturers say to you?
James
Adam Rush
> ejected from a fork. It ain't gentle and it ain't pretty. Especially
> for the guy riding the bike at the time.
Do you have the URL?
Simon Brooke
> well, this all comes down to "the design standard". maybe you can
> show a contrary example, but reality is that manufacturers, by and
> large, /have/ to produce product that works! if there was a "design
> standard" for chains and it was 1/8" width, should we all have to
> stick to riding around on 6-speeds? clearly not! just because
> "design standard" is only 500N, doesn't mean that anyone is fool
> enough to design down to that level just because the "standard" says
> so.
The thing is that it isn't at all difficult to produce a 'design
standard' which doesn't have the potential problems that James Annan
has highlighted. It would be easy to put a crown-nut on the threaded
end of the skewer, with a split-pin passing through a hole in the end
of it, which would stop the nut rotating without interfering in any
way with the quick-release function. A front fork does not _have_ to
have dropouts - motorcycle forks don't, for example - they have axle
bolts which pass through holes in the ends of the forks (usually with
a crown nut and split-pin. The dropouts do not have to face down; they
could, for example, face forward, which would cause braking forces to
push the axle against bthe closed end of the dropout. The caliper
could be positioned forward of the fork leg, which would create forces
upwards into the drop out.
The skewer with crown nut and split-pin idea could easily and
inexpensively be retrofitted to existing bikes (hey, there's a free
business idea for anyone with a fairly basic machine shop). On some
existing bikes it will be possible to reverse the fork sliders without
adversely affecting the geometry.
--
si...@jasmine.org.uk (Simon Brooke) http://www.jasmine.org.uk/~simon/
I'm fed up with Life 1.0. I never liked it much and now it's getting
me down. I think I'll upgrade to MSLife 97 -- you know, the one that
comes in a flash new box and within weeks you're crawling with bugs.
James Annan
I should point out that this was not a wheel pulled out through
application of a disk brake. It was due to a stripped thread in the QR,
possibly due to overtightening, and then the wheel fell out. It's an
illustration of why 'just do up the QR tighter' isn't an answer, and
neither is 'so what, MTBers fall off all the time'. Even at low speed on
a level surface it isn't an everyday sort of fall.
http://www.ne.jp/asahi/julesandjames/home/ride.mpg
James
Jose Rizal
What you really must mean is that "just do up the QR tighter until it
strips" isn't the answer. There's nothing wrong with ensuring that the
QR is "tight enough" before every ride.
Well done on pointing out the actual mechanism involved in the mpg. I
think mentioning this movie in any discussion about the issues in your
disk ejection website (as several people have already done in this
newsgroup) is scaremongering at best, since it depicts none of the
mechanisms proposed and only serves as "fear factor", much like watching
shots of plane crashes.
jim beam
by your standards, all auto manufacturers would be up against the wall
because of the /possibility/ of wheels coming off if lug nuts weren't
tightened properly - as though it were some kind of fundamental design flaw.
there is nothing wrong with lug nuts when properly deployed. similarly,
there is nothing wrong with current bicycle front wheel mounting
systems, when properly deployed.
you are entitled to a contrary opinion, and in that, i wish you luck.
thanks for the debate.
j.
James Annan
> james
>
> by your standards, all auto manufacturers would be up against the wall
> because of the /possibility/ of wheels coming off if lug nuts weren't
> tightened properly - as though it were some kind of fundamental design flaw.
No, the very clear difference is that 'tightened properly' doesn't
work reliably for QRs, as experiments, observations and theory
illustrate. They were never designed for this application. It happens
that the failure rate is low enough for there to be plenty of people
like you who have not seen it, and therefore cannot believe it
happens. I personally do not know anyone who had a Bridgestone tyre
fall apart, rolled their Mercedes A-class car while avoiding a moose
or had a hole knocked in their space shuttle wing, but those faults
still exist.
James
Carl Fogel
[snip]
> as an analogy, consider the wire ropes used in an elevator. there are
> different anchoring methods, but a common one is to open the end of the
> rope into its constituent ropelets, insert a wedge, then embed it into a
> lead or white metal lined cone on the elevator's frame. embedding the
> rope into this soft metal is the key factor in satisfactory anchoring.
> if you tried doing the same thing with hard steel, it would just slip.
> if you think about it, bike brake and gear cables employ the the same
> principle on their cable clamps too - one hard face to apply pressure,
> one soft alloy face for anchoring.
[snip]
Dear Jim,
Regardless of the existence of conspiracies elsewhere,
I'm a willing victim of what seems to be a conspiracy
of posts like yours, which pander shamelessly to my
love of analogies with fascinating details--I had no
idea what the devil holds the elevator up.
Thanks,
Carl Fogel
P.S. Being no engineer, I can only repay you with
some faintly amusing 19th-century elevator-and-politics
doggerel from Ambrose Bierce, the only elevator
poem (as opposed to music) that I know of:
SAFETY-CLUTCH, n. A mechanical device acting automatically to prevent
the fall of an elevator, or cage, in case of an accident to the
hoisting apparatus.
Once I seen a human ruin
In an elevator-well,
And his members was bestrewin'
All the places where he had fell.
And I says, apostrophisin'
That uncommon woful wreck:
"Your position's so surprisin'
That I tremble for your neck!"
Then that ruin, smilin' sadly
And impressive, up and spoke:
"Well, I wouldn't tremble badly,
For it's been a fortnight broke."
Then, for further comprehension
Of his attitude, he begs
I will focus my attention
On his various arms and legs --
How they all are contumacious;
Where they each, respective, lie;
How one trotter proves ungracious,
T'other one an alibi.
These particulars is mentioned
For to show his dismal state,
Which I wasn't first intentioned
To specifical relate.
None is worser to be dreaded
That I ever have heard tell
Than the gent's who there was spreaded
In that elevator-well.
Now this tale is allegoric --
It is figurative all,
For the well is metaphoric
And the feller didn't fall.
I opine it isn't moral
For a writer-man to cheat,
And despise to wear a laurel
As was gotten by deceit.
For 'tis Politics intended
By the elevator, mind,
It will boost a person splendid
If his talent is the kind.
Col. Bryan had the talent
(For the busted man is him)
And it shot him up right gallant
Till his head begun to swim.
Then the rope it broke above him
And he painful come to earth
Where there's nobody to love him
For his detrimented worth.
Though he's livin' none would know him,
Or at leastwise not as such.
Moral of this woful poem:
Frequent oil your safety-clutch.
Porfer Poog
(Bierce routinely made up silly names
for his own rhymes. Col. Bryan is William
Jennings Bryan, who held that rank during
the Spanish-American War, serving in disease
infested Florida and then startling his
supporters by turning into an anti-imperialist:
http://www.spanamwar.com/bryan.htm
A farm populist, Bryan is chiefly remembered
for his opposition to the gold standard
that uncoupled the currency from silver
and for his disastrous attempt to oppose
Clarence Darrow in the Scopes evolution
trial.)
Simon Brooke
James, I'm just on the point of deciding the kit for my partner's
christmas present, and the question of disk brakes vs V brakes is very
topical. Do you know of any current models of forks which you feel are
satisfactory? I'm looking for reasonably lightweight, reasonably high
quality cross-country forks, not lunatic never-mind-the-weight
downhillers.
--
si...@jasmine.org.uk (Simon Brooke) http://www.jasmine.org.uk/~simon/
;; not so much a regugee from reality, more a bogus
;; asylum seeker
James Annan
> James, I'm just on the point of deciding the kit for my partner's
> christmas present, and the question of disk brakes vs V brakes is very
> topical. Do you know of any current models of forks which you feel are
> satisfactory? I'm looking for reasonably lightweight, reasonably high
> quality cross-country forks, not lunatic never-mind-the-weight
> downhillers.
I don't know in much detail (our tandems are right off the oppposite end
of the scale), but there are a few mid-weight bolt-through forks which
may be just about acceptable for a medium sized person (eg Marzocchi).
There may be a suitable Cannondale Lefty.
I've heard that Pace have leapfrogged the competition and put some
abnormally large lawyer lips on their new forks, but I haven't seen them
up close. According to various tame journalists all the manufacturers
are working on fixes, but all the while trying to pretend that they
aren't really, cos they cannot actually admit there is anything wrong
with the current designs...
James
Simon Brooke
> Simon Brooke wrote:
>
> > James, I'm just on the point of deciding the kit for my partner's
> > christmas present, and the question of disk brakes vs V brakes is very
> > topical. Do you know of any current models of forks which you feel are
> > satisfactory? I'm looking for reasonably lightweight, reasonably high
> > quality cross-country forks, not lunatic never-mind-the-weight
> > downhillers.
>
> I don't know in much detail (our tandems are right off the oppposite
> end of the scale), but there are a few mid-weight bolt-through forks
> which may be just about acceptable for a medium sized person (eg
> Marzocchi). There may be a suitable Cannondale Lefty.
A lefty is what I have on my own bike, but she doesn't want a
Cannondale - she's in boycott America mode.
--
si...@jasmine.org.uk (Simon Brooke) http://www.jasmine.org.uk/~simon/
See one nuclear war, you've seen them all.
onefred
This is nothing new. The rider didn't properly tighten his quick release, jumped an
obstacle, and ate crud. It has nothing to do with disc brakes.
Dave
Alan Hoyle
While I can't speak definitively for the original poster, I believe
the video isn't meant to show a specific example of disc-braked wheel
ejection. Rather, it shows an example of what can happen when a front
wheel is lost, irrespective of the underlying cause.
-alan
--
Alan Hoyle - al...@unc.edu - http://www.alanhoyle.com/
"I don't want the world, I just want your half." -TMBG
Get Horizontal, Play Ultimate.
James Annan
> > http://www.ne.jp/asahi/julesandjames/home/ride.mpg
>
>
> This is nothing new. The rider didn't properly tighten his quick release,
Actually, he overtightened it, and the thread stripped. Given the
number of people who say that they do up the QR as tight as possible
to stop it from slipping, it's only surprising there aren't more of
these accidents.
James
onefred
> wheel is lost, irrespective of the underlying cause.
Oh. Ok. Well, yes, these things do happen. It looked very painful and I'm glad that it
wasn't me in that video.
Dave
David Damerell
>While I can't speak definitively for the original poster, I believe
>the video isn't meant to show a specific example of disc-braked wheel
>ejection. Rather, it shows an example of what can happen when a front
>wheel is lost, irrespective of the underlying cause.
But this is not a new fact. While I agree that Mr. Annan has identified a
real problem, this video is pure scaremongering. We know ejection is
nasty, like any major failure of the wheel or forks; the question is
whether it happens, not whether it's nasty.
--
David Damerell <dame...@chiark.greenend.org.uk> Distortion Field!
James Annan
> But this is not a new fact. While I agree that Mr. Annan has identified a
> real problem, this video is pure scaremongering. We know ejection is
> nasty, like any major failure of the wheel or forks; the question is
> whether it happens, not whether it's nasty.
That may be _your_ question, but you must have missed the posters who
said that a front wheel loss is not such a big deal, because MTBers are
used to crashing. There have also been plenty who argue that the
"solution" is to do up the QR tighter. I think this video is of direct
relevance to both of those arguments, but obviously it would be useful
to have someone film a QR coming loose too.
James
Simon Brooke
> Alan Hoyle <al...@unc.edu> wrote:
> >While I can't speak definitively for the original poster, I believe
> >the video isn't meant to show a specific example of disc-braked wheel
> >ejection. Rather, it shows an example of what can happen when a front
> >wheel is lost, irrespective of the underlying cause.
>
> But this is not a new fact. While I agree that Mr. Annan has identified a
> real problem, this video is pure scaremongering. We know ejection is
> nasty, like any major failure of the wheel or forks; the question is
> whether it happens, not whether it's nasty.
I think the question really is, how frequently it happens, and whether
it ever happens with a skewer that was initially correctly adjusted. I
think the fact that it _can happen_ has been adequately
demonstrated. But we work (and ride) with a number of potential
accidents which _can happen_. The rational thing to do is to seek to
assess the risk.
--
si...@jasmine.org.uk (Simon Brooke) http://www.jasmine.org.uk/~simon/
do not sail on uphill water
- Bill Lee