Disc brakes and QRs making headlines

[Doug Taylor]

James Annan <[email protected]> wrote:

>I have absolutely no objection to, and indeed welcom, a bit of intelligent scepticism: it was only
>due to the (correct) insistence of people like yourself, Jon Isaacs and others that a tight QR
>simply cannot pull directly over a lip, that I eventually got round to the conclusion that the QR
>loosened first. And without that final detail, I'd have just been one more crank to be dismissed
>along with the new revolutionary pedal drive and automatic gear changing.
>
>It is, however, getting a bit tedious seeing the same trivial points over and over again from
>bloke-on-a-bike types who imagine that their off-the-cuff opinion is going to unravel several weeks
>worth of careful analysis and inspection by a range of experts. That criticism certainly doesn't
>apply to all the comments posted here, but it describes most of my mailbox!

As a "bloke [or "dude'" on USA side of the pond)-on-a-bike type who has ridden thousands and
thousands of miles off-road with disc brakes without a QR release, knows hundreds of people who have
ridden many more thousands and thousands of miles with disc brakes without a QR release, here is
what I glean as an ignorant and stupid layman from the conclusions of Annan and Brandt:

If you ride some unspecified but significantly large amount of miles with disc brakes, the
QR eventually will loosen to a degree that it could pop over the dropout tabs and the wheel
will fall off.

My own empirical experience (which must be discounted or ignored since it is merely one sample, and
only of a bloke-on-a-bike) is that this period must be large indeed, as I have competed in three 24
Hour races, with 6-7 hours of personal continuous riding, without touching the QR and no mishap.

As Brandt admits, the majority of off-road bikes are transported with front wheel removed, so that
it is reinstalled often before a ride. Most off-road rides last significantly less than 6 hours (try
1, 2 or 3 hours), when the wheel will be removed again.

Solution to the "problem": adjust the QR before you ride your bike (or every 3 or 4 hours or so ).
The odds are utterly overwhelming that you will NEVER have QR loosen to the point of your wheel
falling off.

--dt

 

[Giganews]

I am more than capable of understanding the calculations on your website. Any first-year engineering
student can understand them. I would expect better quality diagrams from most first-year engineering
students, however. Do not be too impressed with yourself. You have not proved Fermat's Last Theorem,
or even performed a particularly thorough analysis. You are presenting as 'results' some
calculations which no technical journal on earth would publish. They would be sent back to you
asking that you either change your tone to properly present this as a topic worthy of research or
perform some actual testing to back up your claims.

Until you perform proper testing I will remain skeptical. At this point all you are doing is
screaming that the sky is falling. You sound like Ralph Nader, for Pete's sake, and you are
oblivious to the danger that you will force changes in an area that you have not properly shown
to be a difficulty (indeed there is a great deal of anecdotal evidence indicating otherwise)
simply because manufacturers will be scared of lawyers. A proper scientist would have a more
rational approach.

Until someone applies a real scientific approach to this problem, I will continue to ride without
one shred of fear that my front wheel which has been happily staying in place for many thousands of
miles of hard riding will fail to do so.

Bill

"James Annan" <[email protected]> wrote in message news:[email protected]...
> GigaNews wrote:
>
> > I think a simple force balance will also tell you that the force pushing
the
> > wheel out of the dropout is dramatically smaller than the force required
to
> > move the wheel if the skewer is tightened properly or even anywhere near properly.
>
> I think the simple force balance calculation on my web pag contradicts your belief. I think if you
> were capable of understanding it, you wouldn't have posted your comment.
>
> James

 

[Mark Hickey]

[email protected] wrote:

>This was discussed at length the first time this subject came under discussion. Recognizing that
>the disengagement force in the axle is great enough to separate it from the dropout in the absence
>of retention lips, even with properly closed QR, it should be apparent that the QR nut will move to
>its downward limit in the retention lips. Subsequently, on the next road shock, it will move back
>to its upper "normal" position. Repeating this motion, although small, will unscrew the QR,
>especially if the closure lever is at the opposite side from the disc brake.

It seems to me that the effect of a properly-closed QR moving up and down in the dropout will be
obvious. On my own MTB (non-disc BTW), the QR engagement zone is an obvious clean circle, with no
signs of movement of the QR's faces while riding.

However, I'm sure there are a lot of folks out there reading this discussion who have a front disc
brake. How many of them see signs of "QR wandering" on their dropouts? It should be very obvious,
since the initial movement occurs with the QR fully closed and tight (which should leave obvious
"trail of damage" across the faces of the dropout.

It would be interesting to do a quick poll of riders at a race to see how many have dropouts showing
signs of QR movement.

Mark Hickey Habanero Cycles http://www.habcycles.com Home of the $695 ti frame

 

[Jobst Brandt]

James Annan writes:

> It is, however, getting a bit tedious seeing the same trivial points over and over again from
> bloke-on-a-bike types who imagine that their off-the-cuff opinion is going to unravel several
> weeks worth of careful analysis and inspection by a range of experts. That criticism certainly
> doesn't apply to all the comments posted here, but it describes most of my mailbox!

Not to worry. This is typical of the bicycle industry and its faithful. It took 15 years for the
concepts presented in "the Bicycle Wheel" to be generally acknowledged and accepted. Until a couple
of years ago, insulting attacks were common fare here on wreck.bike. The greater audience and the
industry are slow to grasp new concepts but time wounds all heels.

Indexed steering, crank failures, crank spindle failures, pedal attachment, fretting of closely
fitting parts, sealed bearings... These are all well discussed subjects here but are only gradually
being recognized.

Patience!

Jobst Brandt [email protected] Palo Alto CA

 

[Gary Young]

Doug Taylor <[email protected]> wrote: <snip>
> As a "bloke [or "dude'" on USA side of the pond)-on-a-bike type who has ridden thousands and
> thousands of miles off-road with disc brakes without a QR release, knows hundreds of people who
> have ridden many more thousands and thousands of miles with disc brakes without a QR release, here
> is what I glean as an ignorant and stupid layman from the conclusions of Annan and Brandt:
>
> If you ride some unspecified but significantly large amount of miles with disc brakes, the QR
> eventually will loosen to a degree that it could pop over the dropout tabs and the wheel will
> fall off.
>
> My own empirical experience (which must be discounted or ignored since it is merely one sample,
> and only of a bloke-on-a-bike) is that this period must be large indeed, as I have competed in
> three 24 Hour races, with 6-7 hours of personal continuous riding, without touching the QR and
> no mishap.

Hell, my grandpappy smoked two packs a day, and he lived to be 100! I don't know what all this
nonsense about smoking is.

You so accurately diagnose the shortcomings of your reasoning one wonders why you bothered to post
this message at all. Is ignorance a point of pride with you?

> As Brandt admits, the majority of off-road bikes are transported with front wheel removed, so that
> it is reinstalled often before a ride. Most off-road rides last significantly less than 6 hours
> (try 1, 2 or 3 hours), when the wheel will be removed again.
>
Perhaps, but there are probably thousands of riders who don't remove their front wheel very often.
That may be a minority, but it's a significant minority.
>
> Solution to the "problem": adjust the QR before you ride your bike (or every 3 or 4 hours or so ).
> The odds are utterly overwhelming that you will NEVER have QR loosen to the point of your wheel
> falling off.

What a wonderful solution! Too bad about the millions of riders who don't read rec.bicycles.tech and
won't know there's even a danger.

Given the fact that the consequences of this type of failure can be quite severe, what is your
problem with encouraging manufacturers to fix it?

 

[Amerigo]

"GigaNews" <[email protected]> ha scritto nel messaggio news:[email protected]...
>
> I am more than capable of understanding the calculations on your website. Any first-year
> engineering student can understand them. I would expect

no one did it before, you are jealous of his idea

> better quality diagrams from most first-year engineering students,
however.
> Do not be too impressed with yourself. You have not proved Fermat's Last Theorem, or even
> performed a particularly thorough analysis. You are presenting as 'results' some calculations
> which no technical journal on earth would publish. They would be sent back to you asking that you
> either change your tone to properly present this as a topic worthy of research or perform some
> actual testing to back up your claims.

specialized, trek, cannondale and all those morons must make the tests

>
> Until you perform proper testing I will remain skeptical. At this point
all
> you are doing is screaming that the sky is falling.

you will fall

You sound like Ralph
> Nader, for Pete's sake, and you are oblivious to the danger that you will force changes in an area
> that you have not properly shown to be a
difficulty
> (indeed there is a great deal of anecdotal evidence indicating otherwise) simply because
> manufacturers will be scared of lawyers. A proper scientist would have a more rational approach.
>
> Until someone applies a real scientific approach to this problem, I will continue to ride without
> one shred of fear that my front wheel which has been happily staying in place for many thousands
> of miles of hard riding will fail to do so.

ah ah

 

[Doug Taylor]

[email protected] (Gary Young) wrote:

>Given the fact that the consequences of this type of failure can be quite severe, what is your
>problem with encouraging manufacturers to fix it?

Absolutely none. Did you pay attention to the entire thread? Do you have reading
comprehension problems?

My point was and is that the minuscule theoretical chance that my front wheel "could" fall off due
to QR failure does NOT impel me immediately to stop riding my mt. bike as it currently is equipped,
or to buy new equipment. The cost is inversely proportional to the benefit. My QR can be and is
adjusted with enough frequency to avoid the predicted (by rarely encountered in fact) result.

Anyone who is so frightened by Annan's theory that he or she locks his current bike in the basement
waiting for the cure is overreacting in the extreme.

If and when: 1) the theory is proven to be correct; 2) alternative equipment is available which
prevents the catastrophic result; and 3) my existing equipment is ready to be replaced, I, like any
rational person, will purchase the upgraded equipment.

Meanwhile, I will continue to use the components which have worked flawlessly for 3 years while I
had my head buried in the sand with the same lack of concern.

--dt

 

[Maki]

In article <[email protected]>, [email protected] (James
Annan) wrote:

> It's a pretty standard estimate, and I didn't want to go to extremes - that would only have led
> (even more) people to say I was exaggerating and scaremongering. It's not critical to the
> calculation.

<disclaimer>I'm not an engineer and I'm not english, so maybe I'm not expressing myself correctly
below. However I'd like to hear your opinion on some points that IMHO should be considered. If what
I write isn't clear or seems incorrect, please tell me and I'll try to rephrase it. Of course maybe
I'm simply dead wrong.</disclaimer>

I think you reasoning on the problem, while basically correct, is in some way "reversed" and
grossly oversimplified. You start with the deceleration and end up with the forces. In real life
you apply a force on the brake lever and you end up with a deceleration. As far as the calculations
are concerned it works in both ways, but the reversed reasoning may lead to erroneous conclusions.
Lets see what I mean. When you squeeze the brake lever your force is transmitted (and multiplied)
to the brake calipers that push the pads against the disc, thus generating a frictional force on
the disc. This generates a reaction force (that acts as a disengaging force) on the wheel axle with
the same magnitude (actually IMHO less, see below). If the braking force is greater than the grip
of the QR surfaces the axle moves, if not it stays in place. That's all there is to it: *the disc
diameter is not relevant*. If you know the friction coefficient of the brake pads you can easily
calculate the force: if you, as me, don't know it of course you have to apply your "reversed"
formula to real world measures (wheel and disk diameter, deceleration and mass). However, once
you've got the numbers you should not consider the disk diameter or the mass anymore, instead you
continue to consider the deceleration as a constant. Given the same caliper+pads+pump and the same
force on the lever, changing the disk or the mass of the cyclist results in a different
deceleration, and in real world situations the constant is the braking system, not the
deceleration. If you double the wheight you don't double the disengaging force, but halve the
deceleration. So when you say that the same brake on a tandem is more challenged it is not entirely
true, since of course you can increase the force on the lever to compensate the increase in mass,
but not that much. Saying that systems with a smaller disk are more prone to failure isn't really
correct either. People that wants to brake hard use big disks for a reason, that is given the same
caliper the wheel/disk ratio is better. Also with larger disks calipers tend to be bigger (i.e.
more piston surface), thus giving a greater force with the same fluid pressure. A bigger disk isn't
really safer, in some cases it can be even worse. To be more clear: I dont't think that a 165mm XC
disc is ever going to be used in a 0.6g deceleration and anybody using it in a DH race with a 6
piston caliper system has bigger problems in his head than on his bike.

Some other considerations:
- I said above that the reaction force is less than the braking force. In your calculation you
consider the wheel free to rotate around the caliper. It is not, there is a *strong* friction on
the pads that works against that. I don't know how to calculate that force, but you can simply try
to move your wheel with the brake sqeezed and the axle removed to see.
- Real world QRs. The PDF that you quote is too old. After those tests were made the ISO standard
has been updated. Still the test shows that most if not all the QRs tested exceded *by far* the
requirements, some even reached the double of todays standards. This is pretty common, engineers
always consider a "security coefficient" when they do their math. I expect todays QRs to be much
better than pre-1996 ones. I've read nearly all the links you give, as well as past threads on the
subject and as a metter of fact most if not all the people that has had problems solved them
changing their vendor. This leads me to think that revamping the ISO standards is probably a Good
Idea, but the real point here is: who verifies the application of the standards? Good QRs are
already good enough.
- Real world data: 0.6g means that you stop a bike running at 50Km/h in 14 metres. Do you really do
that? off road? with a 165mm disk? I haven't done the math because I don't know where the GC is,
but IMHO you are near the physical limit of a MTB *on flat land* assuming a good grip (asphalt).
Running downhill the limit is lower. The steeper the downhill, the lower the limit: at some point
you can't even brake because you do catapult.
- I never liked QRs even if I'm still with V-Brakes. They just look fragile to me, but maybe I'm
just used to motorcycles. I like through-axle hubs better especially in hard riding. I think
that most of the people who is pushing the limits already adopted through-axle solutions
because, brakes aside, they are stiffer and more reliable. People doing XC don't brake that hard
ina any case.

I'm not saying that your theory is wrong, but the practice shows that thousand of bikers are using
disk brakes without ever seeing this problem. I think the above points can, at least partially
explain the difference between theory and practice. IMHO you should back up your assertions with a
more complete and accurate math model (and especially real data about current QRs performance), or
lower the tones on the argument, because you are spreading terror without any real reason: reading
your pages it seems that all the QRs are going to fail eventually, which is unlikely. IMHO a
properly designed and used QR is not going to disengage and I can't believe that nobody between the
people with years of experience involved in designing brakes, forks and hubs has ever considered the
issue. And I don't think they are afraid to adopt a new standard, as they always search excuses to
make us change everything.

As said I'd like to hear your (and other's people here) opinion on the aabove considerations.

--
Fact of life #15: Heads bleed, walls don't.

 

[James Annan]

GigaNews wrote:
> You are presenting as 'results' some calculations which no technical journal on earth would
> publish.

Well you are right on one point. It's certainly unpublishable, but the reason is that it is entirely
trivial. All I have done is apply a simple calculation to a straightforward high-school level
problem (or lower), which apparently has not been properly considered before. Which makes it all the
more disappointing that so many people fail to understand it! I guess one should never underestimate
the audience...

> At this point all you are doing is screaming that the sky is falling.

I repeat for the hard of understanding: I don't know what the failure rate is. I do know of several
cases where severe injury has occurred, apparently due to this failure. I note that 10 million
bridgestone tyres 'only' generated a handful of serious crashes, but were still considered faulty as
a result. Doubtless you would prefer to still be driving on them.

My wife will be very upset that you do not like her picture. But the photograph of Fuji-san is
rather good, don't you think?

James

 

[Tim McNamara]

A common complaint of most telescoping forks for bicycles is that the two legs of the fork do not
necessarily move equally, resulting in complaints of vagueness of steering, etc. There have been
various attempts at overcoming this, including inverting the stanchion and slider, adding large
cross-braces, etc.

Now, if one leg compresses farther than the other, doesn't this add a bending stress to the skewer
and possibly complicate the problems raised by James Annan?

 

[Maki]

In article <[email protected]>, Tim McNamara
<[email protected]> wrote:

> As far as I can tell, simply locating the caliper in front of the fork would eliminate this
> problem. Or even moving it around the rotor so the resultant force isn't in line with the dropout
> might help; surfing around on motorcyle Web sites suggests that those manufacturers have already
> sussed this issue- their placement of calipers tends to be at the top of the rotor (e.g., see the
> Harley Web site), analogous to the placement of rim brakes, as a matter of fact.

ROTFL. Since when Harley is supposed to make motorcycles? Seriously, every high performance
motorcycle made in the last 20 years that I can think of, be it road or off-road, has the calipers
in the very same position of any MTB fork. It just works better this way. And motorcycle forks don't
have dropouts.

--
Fact of life #15: Heads bleed, walls don't.

 

[James Annan]

Doug Taylor wrote:

> As a "bloke [or "dude'" on USA side of the pond)-on-a-bike type who has ridden thousands and
> thousands of miles off-road with disc brakes without a QR release, knows hundreds of people who
> have ridden many more thousands and thousands of miles with disc brakes without a QR release, here
> is what I glean as an ignorant and stupid layman from the conclusions of Annan and Brandt:
>
> If you ride some unspecified but significantly large amount of miles with disc brakes, the QR
> eventually will loosen to a degree that it could pop over the dropout tabs and the wheel will
> fall off.

I see others have replied, but I'd just like to point out that I did not and do not assert this.
Surely many individual cases are completely safe. If a particular QR bites into a particular fork
sufficiently that it cannot ever move at all under any realistic force, then that case will not fail
by this method.

Quite possibly your fork and QR fall into this category. Quite possibly, the majority do, but
demonstrably many do not. I see no reliable method of distinguishing them a priori.

Maybe you should ask your 'hundreds of people' if any of them have ever experienced their wheel
slipping at all. That is the first step on the way to failure, and the whole process can happen (and
has been reported) on a single descent. Once it starts to loosen, this can accelerate very rapidly.

James

 

[Tim McNamara]

In article <[email protected]>, Doug Taylor
<[email protected]> wrote:

> [email protected] (Gary Young) wrote:
>
> >Given the fact that the consequences of this type of failure can be quite severe, what is your
> >problem with encouraging manufacturers to fix it?
>
> Absolutely none. Did you pay attention to the entire thread? Do you have reading comprehension
> problems?

Apparently you have some sort of reading impairment, however. You certainly do not read with due
attention- I hope you are more alert when you ride your bike.

> My point was and is that the minuscule theoretical chance that my front wheel "could" fall off
> due to QR failure does NOT impel me immediately to stop riding my mt. bike as it currently is
> equipped, or to buy new equipment. The cost is inversely proportional to the benefit. My QR
> can be and is adjusted with enough frequency to avoid the predicted (by rarely encountered in
> fact) result.

It is not a miniscule theoretical chance, which you would understand if you had been paying
attention.

> Anyone who is so frightened by Annan's theory that he or she locks his current bike in the
> basement waiting for the cure is overreacting in the extreme.

You are the only one advocating this interpretation. This suggests that (1) you're a hysteric or (2)
you are trying to distort what James Annan has written in order to prove yourself right. I suspect
it's the latter.

> If and when: 1) the theory is proven to be correct; 2) alternative equipment is available which
> prevents the catastrophic result; and
> 3) my existing equipment is ready to be replaced, I, like any rational person, will purchase the
> upgraded equipment.

(1) The theory appears quite reasonable and has been proven in a number of field tests.
Unfortunately those folks didn't know they were doing field testing, sort of like buying a
Microsoft product. Fortunately for those using the latter, you'll only be inconvenienced if it
fails in some way. (2) Alternate equipment is available- it's called a rim brake. There are
several different designs from which to choose- lighter, safer and less expensive than disk
brakes. (3) Only you can decide when the equipment is ready for replacement.

> Meanwhile, I will continue to use the components which have worked flawlessly for 3 years while I
> had my head buried in the sand with the same lack of concern.

Well, then, good luck. After all, it's your cost-benefit ratio. But I very much doubt you will use
it with the "saame lack of concern." You're going to just double check that QR or clamp it down just
a smidge tighter, make sure there's no dirt on the clamping areas, etc. That's just human nature.

 

[Carlton Reid]

Many on here have the passwords to http://www.bikebiz.co.uk I have no problem with folks
cutting-and-pasting all the QR/disc brake articles I've done. There's been three to date. More will
no doubt follow.

You'll see that the articles include lots of question marks and 'maybes' and words like 'theory'. I
don't think the pieces are sensationalistic. But if there's a real QR problem out there, and I
incline to think there is, I want the bike trade to do something about
it.

The problem is fixable, so let's fix it.

 

[Andreas Oehler]

Fri, 16 May 2003 22:09:48 GMT, Maki:

>Seriously, every high performance motorcycle made in the last 20 years that I can think of, be it
>road or off-road, has the calipers in the very same position of any MTB fork. It just works better
>this way.

Please explain why. I don't see a reason. Important for the braking are the diameter of the disc,
the force of the pads pressed on the disc, the coefficient of friction (and to some degree heat
transfer, wear, stiffness of the mount).

A friend has two bikes equipped with Sachs Powerdisc (the first mass produced hydraulik disc brake
for bicycles). The brake caliper is mounted to the front of the fork. See it on

http://www.enhydralutris.de/Fahrrad/HPV-Bilder/OlafSchultz/ATB/index.html
http://www.objectfarm.org/People/Tomi/HPV/Photos/GreenAmigo.406.Side.Photo.jpg

The brake is a little too heavy but works extremely well.

> And motorcycle forks don't have dropouts.

Yes. Without dropouts it is no problem to have reaction forces, which try to move the axle down.

Andreas

 

[Doug Taylor]

"Tim McNamara" <[email protected]> wrote in message news:timmcn-

(2) Alternate equipment is available- it's
> called a rim brake. There are several different designs from which to choose-

Cantis, which modulate but don't stop, or V-s, which stop but don't modulate...

Annan, with justification I admit, decries the "bloke-on-a-bike" who argues against his theory out
of emotion and without knowledge or critical reasoning in support. Only thing worse is you: a
"bloke-off-a-bike" who appears to be blowing smoke. If you ride off-road more than a few times a
month, I'll eat my QR. The majority of riders who spend a lot of time on mountain bikes use discs
because of superior performance: stopping power AND modulation (old thread). They will not be quick
to spend gobs of cash (see below) replacing them with inferior equipment unless and until there is a
real reason to.

> lighter

Ever hear of XTR? Negligably heavier than V-s; standard equipment in 2003 for world cup x-c racers
who use Shimano group.

>safer

A theory has been proposed, which appears to be sound on paper. There is anecdotal evidence to
support it, and that which does not. It has yet to be "proven" by actual testing and measurement.
Annan will admit as much, I wager.

>and less expensive than disk brakes.

Not if you are going to revamp your current system in reaction to the theory. That will run you new
wheels as well as new brakes. Cost exceeding benefit.

>> You're going to just double check that QR or clamp it down just a
> smidge tighter, make sure there's no dirt on the clamping areas, etc. That's just human nature.

Well, duh! That will fix the problem for the time being. And doesn't cost a dime.

 

[B. Sanders]

"Doug Taylor" <[email protected]> wrote in message news:[email protected]...
> "Tim McNamara" <[email protected]> wrote in message news:timmcn-
>
> (2) Alternate equipment is available- it's
> > called a rim brake. There are several different designs from which to choose-
>
> Cantis, which modulate but don't stop, or V-s, which stop but don't modulate...
>
> Annan, with justification I admit, decries the "bloke-on-a-bike" who
argues
> against his theory out of emotion and without knowledge or critical reasoning in support. Only
> thing worse is you: a "bloke-off-a-bike" who appears to be blowing smoke. If you ride off-road
> more than a few times
a
> month, I'll eat my QR. The majority of riders who spend a lot of time on mountain bikes use
> discs because of superior performance: stopping power AND modulation (old thread). They will not
> be quick to spend gobs of cash (see below) replacing them with inferior equipment unless and
> until there
is
> a real reason to.
>
> > lighter
>
> Ever hear of XTR? Negligably heavier than V-s; standard equipment in 2003 for world cup x-c racers
> who use Shimano group.

I have XTR stuff all over my bikes. What do you mean by "negligibly heavier?" Let's see some numbers
for total bike weight with discs vs. same bike with superlight V-brakes. If there's less than 1.5
pounds of difference, I'll eat my hat. It's more like 2 lbs of difference. There are no superlight
disc-equipped bikes, AFAIK.

> >safer
>
> A theory has been proposed, which appears to be sound on paper. There is anecdotal evidence to
> support it, and that which does not. It has yet to
be
> "proven" by actual testing and measurement. Annan will admit as much, I wager.
>
> >and less expensive than disk brakes.
>
> Not if you are going to revamp your current system in reaction to the theory. That will run you
> new wheels as well as new brakes. Cost
exceeding
> benefit.

I'm avoiding the whole problem by simply not using discs. How is that more expensive? I'd say it
sounds like discs already have a cost that well exceeds benefit, on every score.

> >> You're going to just double check that QR or clamp it down just a
> > smidge tighter, make sure there's no dirt on the clamping areas, etc. That's just human nature.
>
> Well, duh! That will fix the problem for the time being. And doesn't
cost
> a dime.

My $40-per-bike basic Avid V-brakes outperform my $200-per-bike* Avid discs on every score,
including modulation, and don't require off-center dishing on the front wheel as front disc hubs do.
The Avid V's are also 2 *pounds* lighter (including extra wheel and fork weight) than the discs. I
can think of better things to do with $500 than put XTR disc brakes on my bike and add 2 lbs of
weight in the process. BTW: With V-brakes, I rarely locked up the wheels unintentionally. With
discs, I do it all the time. So what were you saying about "superior modulation?" Please cite
studies to document this superiority, including population studies of riders who prefer and use
discs over V-brakes.

Barry

* Total cost to switch to discs is more like $350 to $400, since equivalent quality disc-compatible
wheels, calipers and rotors must be purchased. This of course also presumes that the frame is
disc ready.

 

[Jon Bond]

"B. Sanders" <[email protected]> wrote in message news:NoAxa.919922$S_4.931139@rwcrnsc53...
>snip<
> > Ever hear of XTR? Negligably heavier than V-s; standard equipment in
2003
> > for world cup x-c racers who use Shimano group.
>
> I have XTR stuff all over my bikes. What do you mean by "negligibly heavier?" Let's see some
> numbers for total bike weight with discs vs.
same
> bike with superlight V-brakes. If there's less than 1.5 pounds of difference, I'll eat my hat.
> It's more like 2 lbs of difference. There are no superlight disc-equipped bikes, AFAIK.

>snip<

Ok, trying to compare very similar components, so we'll go Crossmax SL's (disc/nodisc) and new XTR.
I am, however, using manufacturer's specs, but we'll figure they're pretty much off the same since
its the same companies.

DISC SETUP Crossmax SL Discs - 1685g '03 XTR Shift/Lever - 442g XTR Disc Brakes (F+R)- 198g Stan's
Rotors (F+R) - 108g

Total - 2433g
5.36lbs

NON DISC Setup Crossmax SL - 1500g '03 XTR Shift/Lever - 412g XTR V-Brake pair - 398g

Total: 2310g
6.09lbs

That's only just over a quarter pound difference. Even if they aren't counting bolts and cables,
which will almost even out, maybe add a bit more to the discs, you're still well under a pound.

Sorry, hope you like the taste of hat. You can use ketchup if you want.

Jon Bond

 

[Mark McMaster]

Doug Taylor wrote:
> "Tim McNamara" <[email protected]> wrote in message news:timmcn-
>
> (2) Alternate equipment is available- it's
>
>>called a rim brake. There are several different designs from which to choose-
>
>
> Cantis, which modulate but don't stop, or V-s, which stop but don't modulate...
>
> Annan, with justification I admit, decries the "bloke-on-a-bike" who argues against his theory out
> of emotion and without knowledge or critical reasoning in support. Only thing worse is you: a
> "bloke-off-a-bike" who appears to be blowing smoke. If you ride off-road more than a few times a
> month, I'll eat my QR. The majority of riders who spend a lot of time on mountain bikes use discs
> because of superior performance: stopping power AND modulation (old thread). They will not be
> quick to spend gobs of cash (see below) replacing them with inferior equipment unless and until
> there is a real reason to.
>
>
>>lighter
>
>
> Ever hear of XTR? Negligably heavier than V-s; standard equipment in 2003 for world cup x-c racers
> who use Shimano group.

According to Velonews, Shimano sponsored racers are required to use the Shimano disk brake. In other
words, Shimano disk brakes are being used by pro racers not because they are necessarily better, but
because they are contractually obligated to use them.

That points out the irony about contractual sponsorship agreements that seems to be lost on the
buying public: It is hardly a strong endorsement for a product if they have to pay people to use it.

Mark McMaster [email protected]

 

[B. Sanders]

"Jon Bond" <[email protected]> wrote in message
news:0HAxa.920133$S_4.931192@rwcrnsc53...
>
> "B. Sanders" <[email protected]> wrote in message news:NoAxa.919922$S_4.931139@rwcrnsc53...
> >snip<
> > > Ever hear of XTR? Negligably heavier than V-s; standard equipment in
> 2003
> > > for world cup x-c racers who use Shimano group.
> >
> > I have XTR stuff all over my bikes. What do you mean by "negligibly heavier?" Let's see some
> > numbers for total bike weight with discs vs.
> same
> > bike with superlight V-brakes. If there's less than 1.5 pounds of difference, I'll eat my hat.
> > It's more like 2 lbs of difference. There
are
> > no superlight disc-equipped bikes, AFAIK.
>
> >snip<
>
> Ok, trying to compare very similar components, so we'll go Crossmax SL's (disc/nodisc) and new
> XTR. I am, however, using manufacturer's specs, but we'll figure they're pretty much off the same
> since its the same
companies.
>
> DISC SETUP Crossmax SL Discs - 1685g '03 XTR Shift/Lever - 442g XTR Disc Brakes (F+R)- 198g Stan's
> Rotors (F+R) - 108g
>
> Total - 2433g
> 5.36lbs
>
> NON DISC Setup Crossmax SL - 1500g '03 XTR Shift/Lever - 412g XTR V-Brake pair - 398g
>
> Total: 2310g
> 5.09lbs
>
> That's only just over a quarter pound difference. Even if they aren't counting bolts and cables,
> which will almost even out, maybe add a bit
more
> to the discs, you're still well under a pound.

What's the performance of this setup? Are 108grams/pair rotors reliable? Bet they get pretty hot and
warp like crazy. I had excellent CNC'd brakes on my Merlin that were about 280g/set, which adds
another 1/3 of a pound to your total weight difference. Also, let's see real-world weight
measurements on those components. Under 200 grams for both front and rear for XTR calipers? With
hoses? Yeah, right.

So, the moral of the story is that if you live in the upper stratosphere of componentry, and have a
*HUGE* budget for wheels and brakes, then *maybe*, just maybe you might not totally screw up your
bike with disc brakes. You'll still add almost half a pound to your superlight steed, and your
front wheels will be dished. But hey, you'll sport the latest fad, and that's worth a lot, isn't
it? Oops! You seem to have ripped loose one of those super-light hydraulic hoses on a tree branch,
and now your brakes are useless. Guess you'd better order another $50 hose and wait a couple of
weeks for delivery.

Why should I switch from V-brakes? To make an $800 fashion statement? Still haven't seen any
compelling evidence for disc superiority (and yes, I have a disc equipped bike with roughly
equivalent components to my V-equipped bike).

Barry