that old chestnut

"Marz" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Don Whybrow said:

... and there are problems with disks as well. You have to make sure to
keep the surface clean, improperly set up hydraulic systems can get air
bubbles degrading the performance and your wheel could pop out of the
drop-outs under heavy loads.

Not that [censored] about wheels popping out due to disk brakes, please. A
few idiots failed to work out how a QR works and they start blaming the
positioning of the disk brakes.

Um, do you actually know the mechanics behind the issue? And are you aware
that some fork manufacturers have redesigned their dropouts to remove the
problem, and others moved the brake mount to achieve the same?

cheers,
clive

in message <[email hidden]>, Doki

(') said:

"Don Whybrow" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Tony Raven said:

Doki wrote on 07/01/2007 23:45 +0100:

>
> Well, there's the mighty Sheldon to contend with too. TBH I wouldn't
> be happy using any braking system that can lock up suddenly, no matter
> how rare it is, particularly when other reliable systems are
> available. Faceplants aren't nice.

OTOH rim brakes are not without their problems. Poorer performance in
wet weather, susceptible to worn rim failures and overheating on
downhills, can ice over in cold weather leading to complete loss of
braking etc etc.

... and there are problems with disks as well. You have to make sure to
keep the surface clean, improperly set up hydraulic systems can get air
bubbles degrading the performance

You don't have to clean brake disks. Any decent disk is slotted and waved
so that the pad constantly wipes the disk clean. You do have to avoid
getting grease and oil on the disk. Bleeding the brakes is something that
you need to do once in a blue moon, as evidenced by the number of cars
with hydraulic disk brakes that go 10 years without having their brakes
bled without falling off the road.

Quoted message said:

and your wheel could pop out of the drop-outs under heavy loads.

Fix it with a decent QR and proper drop outs.

Errr... or not. Read up on the literature of disk ejection. The only safe
front disk systems in common use are through-axle systems, the Cannondale
Lefty, and the (very similar) USE SUB. None of these have quick releases.
It would be possible to build a fork with quick release which is
protection against disk ejection, but so far I don't believe this has been
done.

--
[email hidden] (Simon Brooke) http://www.jasmine.org.uk/~simon/

;; Men never do evil so completely and cheerfully as when they
;; do it from  religious conviction."          -- Pascal

Simon Brooke said:

in message <[email hidden]>, Doki

(') said:

"Don Whybrow" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

and your wheel could pop out of the drop-outs under heavy loads.

Fix it with a decent QR and proper drop outs.

Errr... or not. Read up on the literature of disk ejection. The only safe
front disk systems in common use are through-axle systems, the Cannondale
Lefty, and the (very similar) USE SUB. None of these have quick releases.
It would be possible to build a fork with quick release which is
protection against disk ejection, but so far I don't believe this has been
done.

Doesn't the Cotic Roadrat, as recently built by Mr Larrington, come with
the forks back to front to provide this protection. I can't tell from
the pics if Depravo has QR's though.

--
Don Whybrow

Sequi Bonum Non Time

'Tis an ill wind that blows no minds.

"Dave" <[email hidden]> wrote in message
news:[email hidden]...
Hello,

I want to buy a new bike (you can see where this is going, im ever so
sorry)

It's my primary mode of transport, the gf has a car but i'd rather
cycle.

I cycle 8 miles each way to work over tarmac with a big old hill in the
middle,
country lanes with potholes that could swallow a deer
(indeed i managed to burst the 2 left tyres on a hire car down this
lane one day when forced wide) and also through a forest path which has
-
up to a foot of mud in places,
branches strewn across the place and
is primarily used as a bridal path for what looks like shire horses!

i currently ride a gt rts3 with slicks and downhill handle bars wide
flatish things, i reckon i;ve done about 6000 miles on it.

the bike i was looking at was the carrera subway 8 but i've read about
poor braking performance from the hubs? some bloke boiled the grease. i
want good brakes as i do break 30mph occasionally
(downhill with a 32mph tailwind).

i was happy with paying about £300 for the new steed (i've had the gt
for about 8 years now.)
but i've since found out about the tax free benefit in kind scheme for
cycles and have arranged with work to buy it, so im happy to spend a
bit more maybe £700.

I like the mudguards and chain guard idea so i can ride it about town
in the wet if im visiting people and not getting dirty.

so there you go, all and any advice greatfully recieved.
thanks
Dave

Do they *make* 4 x 4 pushbikes? sounds like you might need one .....

:o)
--
Ian

Clive George said:

"Marz" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Don Whybrow said:

... and there are problems with disks as well. You have to make sure to
keep the surface clean, improperly set up hydraulic systems can get air
bubbles degrading the performance and your wheel could pop out of the
drop-outs under heavy loads.

Not that [censored] about wheels popping out due to disk brakes, please. A
few idiots failed to work out how a QR works and they start blaming the
positioning of the disk brakes.

Um, do you actually know the mechanics behind the issue? And are you aware
that some fork manufacturers have redesigned their dropouts to remove the
problem, and others moved the brake mount to achieve the same?

cheers,
clive

I read most of it and it was bunk to say the least. Yes, if you're
riding around with incorrectly tighten QRs (loose) and happen to pop a
wheelie while pulling the front brake hard, Annan's theory that the
wheel may eject is possibly correct. But it has not been demonstrated
that the forces acting through the drop outs while braking are great
enough to eject a wheel held in place by correctly tightened QRs.

Annan and others have mentioned that these rotational forces loosen QRs
as the bike is ridden, but so do any vibrations that occur during
riding. And this is why a compentent cyclist checks QR tension before
each ride.

And the fact that manufacturers have reacted in such a way shows a
greater fear of lawyers than of any actual facts. Lawyer lips on forks
weren't put there due to any design fault, but because some folks are
stupid.

Laters,

Marz

"Marz" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

And the fact that manufacturers have reacted in such a way shows a
greater fear of lawyers than of any actual facts. Lawyer lips on forks
weren't put there due to any design fault, but because some folks are
stupid.

Would you ride a bike with front QR, front disk with the dropouts in the
normal orientation, and no lawyer lips?

cheers,
clive

Marz said:

Not that [censored] about wheels popping out due to disk brakes, please. A
few idiots failed to work out how a QR works and they start blaming the
positioning of the disk brakes.

After doing the calculations on rejection forces, and after reading the
relevant B.S. on retention, both for a QR as legally required, and for
the "lawyer lips" when the QR is loose: there is no way I would ride a
bike with the combination of a disk brake with caliper behind the axle and
a U-shaped vertical dropout.

That's for a conventional upright for which the rejection force and the
legally required retaining force are very close to equal; for a heavily
loaded upright, a tandem or a recumbent the achievable rejection force is
somewhat greater than the legal retention force.

I like my margins for error a bit larger than zero. YMMV.

Mike

Clive George said:

"Marz" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

And the fact that manufacturers have reacted in such a way shows a
greater fear of lawyers than of any actual facts. Lawyer lips on forks
weren't put there due to any design fault, but because some folks are
stupid.

Would you ride a bike with front QR, front disk with the dropouts in the
normal orientation, and no lawyer lips?

cheers,
clive

Without wandering outside to check, I think my old Manitou's have
lawyer lips (can you buy forks without them), but everything else
checks out, QR, 6 inch front rotor. Same for my Maguras, but my 66s
have a 20mm through axle and 8 inch rotors.

What's your point?

Laters,

Marz

"Marz" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Clive George said:

"Marz" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

And the fact that manufacturers have reacted in such a way shows a
greater fear of lawyers than of any actual facts. Lawyer lips on forks
weren't put there due to any design fault, but because some folks are
stupid.

Would you ride a bike with front QR, front disk with the dropouts in the
normal orientation, and no lawyer lips?

Without wandering outside to check, I think my old Manitou's have
lawyer lips (can you buy forks without them), but everything else
checks out, QR, 6 inch front rotor. Same for my Maguras, but my 66s
have a 20mm through axle and 8 inch rotors.

What's your point?

Your manitous almost certainly have them. Which means you aren't really in a
position to answer the question.

The thing is, QRs aren't designed to be strong enough to hold against disk
brake ejection forces. Lawyer lips can help them.

Do the sums like James did.

cheers,
clive

Marz said:

Without wandering outside to check, I think my old Manitou's have
lawyer lips (can you buy forks without them), but everything else
checks out, QR, 6 inch front rotor. Same for my Maguras, but my 66s
have a 20mm through axle and 8 inch rotors.

What's your point?

Don't do "stoppies" on the Manitous, nor brake hard with panniers full of
groceries. Anything with a through axle is OK.

Mike

Mike Causer said:

Marz said:

Without wandering outside to check, I think my old Manitou's have
lawyer lips (can you buy forks without them), but everything else
checks out, QR, 6 inch front rotor. Same for my Maguras, but my 66s
have a 20mm through axle and 8 inch rotors.

What's your point?

Don't do "stoppies" on the Manitous, nor brake hard with panniers full of
groceries. Anything with a through axle is OK.

Mike

Err, the forks are fine and the QR has never become loose and allowed
the wheels to eject in about 4 years of use. I'm estimating that my
combined rider-bike-camelpak weight is about 260 pounds and never had a
problem braking or pulling 'stoppies'.

Does anyone know anyone to whom this urban-myth may have happened to?

laters,

Marz

"Marz" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Mike Causer said:

Marz said:

Without wandering outside to check, I think my old Manitou's have
lawyer lips (can you buy forks without them), but everything else
checks out, QR, 6 inch front rotor. Same for my Maguras, but my 66s
have a 20mm through axle and 8 inch rotors.

What's your point?

Don't do "stoppies" on the Manitous, nor brake hard with panniers full of
groceries. Anything with a through axle is OK.

Err, the forks are fine and the QR has never become loose and allowed
the wheels to eject in about 4 years of use. I'm estimating that my
combined rider-bike-camelpak weight is about 260 pounds and never had a
problem braking or pulling 'stoppies'.

Does anyone know anyone to whom this urban-myth may have happened to?

Yes. Which shows how little of this you've read in detail, coz you've even
mentioned him by name.

clive

Clive George said:

"Marz" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Quoted message said:

Does anyone know anyone to whom this urban-myth may have happened to?

Yes. Which shows how little of this you've read in detail, coz you've even
mentioned him by name.

Not to mention Russ Pinder.

--
Dave...

Clive George said:

"Marz" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Mike Causer said:

On Mon, 08 Jan 2007 18:50:10 -0800, Marz wrote:

> Without wandering outside to check, I think my old Manitou's have
> lawyer lips (can you buy forks without them), but everything else
> checks out, QR, 6 inch front rotor. Same for my Maguras, but my 66s
> have a 20mm through axle and 8 inch rotors.
>
> What's your point?

Don't do "stoppies" on the Manitous, nor brake hard with panniers full of
groceries. Anything with a through axle is OK.

Err, the forks are fine and the QR has never become loose and allowed
the wheels to eject in about 4 years of use. I'm estimating that my
combined rider-bike-camelpak weight is about 260 pounds and never had a
problem braking or pulling 'stoppies'.

Does anyone know anyone to whom this urban-myth may have happened to?

Yes. Which shows how little of this you've read in detail, coz you've even
mentioned him by name.

clive

No, not have known or read a report by someone out there on the web,
but actually have a mate/friend/colleague to whom this may have
happened? This group must at least contain about 100000 hours of
individual ride time experiences. Somebody may have directly
experienced this and if so are they able to say that mechanicaly the
bike was fine before the ride (tight QRs) and the wheel ejection was
due to the disk brakes.

I still think this is a bunk concern, an urban myth, BUT I could be
wrong in this and have only been lucky in the last 7 years of disk
brake usage.

In thinking about this problem, I've only ever used reasonable to good
kit on my bikes. For example, never spending less than a tenner on a
set of skewers. Is this more of a problem when using lower quality and
possible inferior productucts which may pass minimum requirements, but
are no where near as good as a quality product from Salsa or Hope?

Laters,

Marz

Marz said:

I still think this is a bunk concern, an urban myth, BUT I could be
wrong in this and have only been lucky in the last 7 years of disk
brake usage.

So, apart from the fact that it hasn't happened to you or anyone you know,
do you have any reason to believe it's an urban myth? The calculations
certainly suggest that there is a potential problem.

Quoted message said:

In thinking about this problem, I've only ever used reasonable to good
kit on my bikes. For example, never spending less than a tenner on a
set of skewers. Is this more of a problem when using lower quality and
possible inferior productucts which may pass minimum requirements, but
are no where near as good as a quality product from Salsa or Hope?

Most boutique skewers are exposed-cam, which generally apply less clamping
force than basic Shimano ones. They're also more likely to have the
serrated surface made of softer aluminium rather than steel.

http://www.sheldonbrown.com/skewers.html

Anthony

"Marz" <[email hidden]> wrote in message
news:[email hidden]...

Quoted message said:

Quoted message said:

Quoted message said:

Does anyone know anyone to whom this urban-myth may have happened to?

Yes. Which shows how little of this you've read in detail, coz you've
even
mentioned him by name.

No, not have known or read a report by someone out there on the web,
but actually have a mate/friend/colleague to whom this may have
happened?

Like I said, yes.

Quoted message said:

I still think this is a bunk concern, an urban myth, BUT I could be
wrong in this and have only been lucky in the last 7 years of disk
brake usage.

a) It's not an urban myth. It happened - look at the photos.
b) If you've got lawyer lips, it's less important, and TBH on a solo you'll
probably get away with it most of the time - but it's still a [censored] design.

Quoted message said:

In thinking about this problem, I've only ever used reasonable to good
kit on my bikes. For example, never spending less than a tenner on a
set of skewers. Is this more of a problem when using lower quality and
possible inferior productucts which may pass minimum requirements, but
are no where near as good as a quality product from Salsa or Hope?

Actually Shimano skewers are supposed to be better than most. Some of the
expensive kit is that which is likely to be worst. (I wouldn't get another
Hope one, but for different reasons - very pretty but the shimano one works
better)

clive

Marz said:

I read most of it and it was bunk to say the least. Yes, if you're
riding around with incorrectly tighten QRs (loose) and happen to pop a
wheelie while pulling the front brake hard, Annan's theory that the
wheel may eject is possibly correct.

Um, if you pop a wheelie while pulling the brake, there's hardly any
ejection force. Given that this is apparently not self-evident to
you, I won't be placing a great deal of weight on the rest of your
opinion on the topic.

regards, Ian SMith

--
|\ /| no .sig
|o o|
|/ \|

Ian Smith said:

Marz said:

I read most of it and it was bunk to say the least. Yes, if you're
riding around with incorrectly tighten QRs (loose) and happen to pop a
wheelie while pulling the front brake hard, Annan's theory that the
wheel may eject is possibly correct.

Um, if you pop a wheelie while pulling the brake, there's hardly any
ejection force. Given that this is apparently not self-evident to
you, I won't be placing a great deal of weight on the rest of your
opinion on the topic.

Bad example, but the only time I've ever witnessed a front wheel being
ejected (falling out) was when friends have popped wheelies.

There's something quite wrong with Annan calculations and I can't put
my finger on what that is. Time to dig out pen, paper and casio...

One thing I do notice is that the forks he bases his calculations on
are a set of Bombers where the disk mount is almost level with the drop
outs. Not something I've seen on many forks and not at all on any of
the forks I've ever owned (SIDs, Magura, Manitou, Marzzochi). So is
this problem only a concern in certain fork designs? Is there a
critical point (relative position of pad to QR) at which disk ejection
becomes a possiblity?

Laters,

Marz

Ian Smith wrote on 10/01/2007 13:54 +0100:

Quoted message said:

The rest of your argument is similarly weak - murder never happens
because you've never murdered anyone, and never seen any of your mates
murder anyone.

OTOH the arguments for are akin to "there's lots of dead people, they
must all have been murdered". Some people have grasped every example of
an accident where a wheel came out and disk brakes were involved as
evidence of the Annan theory.

--
Tony

"...has many omissions and contains much that is apocryphal, or at least
wildly inaccurate..."
Douglas Adams; The Hitchhiker's Guide to the Galaxy

ian henden said:

Do they *make* 4 x 4 pushbikes? sounds like you might need one .....

:o)
--
Ian

🙂 heh i do want my cake and eat it it would seem.
a gary fisher cake with slick tyres was an idea i toyed with for a
while but i think i'd be better off saving the weight.

thank you ladies and gentlemen for your advice and musings

Dave