Beloki losing rear tire... Tubular problem?

"Sheldon Brown" wrote in message
...
..

It appears to me that the skid began _before_ the turn, as Beloki was
trying to slow in preparation for the turn, but he had not begun to
actually lean over into the sharp part of the turn. I believe this
crash would not have happened if he had not used his rear brake.

Lance went over the same pavement, also braking, and didn't fishtail.

Lance clearly stated that Beloki "locked 'em up" in the turn. He was closest
to him and had a good view of his rear wheel. I also assume he knows what a
rear wheel lockup looks like.

whitfit- When reading that Beloki had rolled his rear tire, it brought to
mind
two things; first, Jobst's assertions that tubulars are bad in the
alps due to melting glue, and second, that heavy rear braking in that
situation has been discussed as a bad thing in this group. He was
also using an 18mm tire. BRBR

Pix have shown it to be a clincher....

Peter Chisholm
Vecchio's Bicicletteria
1833 Pearl St.
Boulder, CO, 80302
(303)440-3535
http://www.vecchios.com
"Ruote convenzionali costruite eccezionalmente bene"

Mike J- From the photos, it appears that he was riding on clinchers, not
tubulars
(based on what looks very much like a Velox rimstrip on his wheel). BRBR

Closeups showed it to be a clincher..from the .racing NG...

Peter Chisholm
Vecchio's Bicicletteria
1833 Pearl St.
Boulder, CO, 80302
(303)440-3535
http://www.vecchios.com
"Ruote convenzionali costruite eccezionalmente bene"

Benjamin Weiner wrote:

Sheldon Brown wrote:

if it weren't for my belief
that this crash offers a valuable lesson to all cyclists on the dangers
of inappropriate use of the rear brake.

Again, for those who tuned in late, here's my article on this important
topic. It might save your life: http://sheldonbrown.com/brakturn.html

I'm sure you're right that he braked and locked up the rear wheel,
esp. as he wasn't very far into the turn. It is possible to skid
the rear on hairpins without rear braking, especially if the road
is slick or loose.

I'm certain it is possible to skid the rear without any braking.
I did it on a wet road on my commute home just two days ago.
I probably had about 15 lbs in my panniers.

Obviously, if a surface is slippery enough, you can skid without
braking.

Stergios

(Qui si parla Campagnolo) writes:


Mike J- From the photos, it appears that he was riding on clinchers, not
tubulars
(based on what looks very much like a Velox rimstrip on his wheel). BRBR

Closeups showed it to be a clincher..from the .racing NG...

The picture isn't definitive. However, Lance said that the wheel
exploded; by that I assume he meant he heard the tube violently
rupturing. Does that happen when a tubular is rolled? I wouldn't
expect it. But it definitely occurs when a clincher comes off.

Joe Riel

P.S. Hi Pete---the Ranchos race is this Sunday; we'll discount the
entry fee for a former member.

On Tue, 15 Jul 2003 11:39:20 +0000, Steven L. Sheffield wrote:

On 7/14/03 3:51 PM, in article
, "Mike Jacoubowsky/Chain
Reaction Bicycles" wrote:

From the photos, it appears that he was riding on clinchers, not
tubulars (based on what looks very much like a Velox rimstrip on his
wheel).


Or a sew-up's base-tape that peeled away from the tire and stuck to the
rim.

Nah. That would have been pulled away in spots at least. But a decent
tubular, and one would expect he would have them, would not lose its base
tape, and certainly not completely as that would have to have been. It
was a clincher.

--

David L. Johnson

__o | This is my religion. There is no need for temples; no need for
_`\(,_ | complicated philosophy. Our own brain, our own heart is our
(_)/ (_) | temple. The philosophy is kindness. --The Dalai Lama

"Sheldon Brown" wrote in message
...
.

It appears to me that the skid began _before_ the turn, as Beloki was
trying to slow in preparation for the turn, but he had not begun to
actually lean over into the sharp part of the turn. I believe this
crash would not have happened if he had not used his rear brake.

Lance went over the same pavement, also braking, and didn't fishtail.



I watched the video again, and Lance does skid the rear while
trying to avoid the crash. He gets a little bit sideways while
on the lighter-colored pavement, but his wheel catches again
on the dark patch and he straightens out.

It is most obvious in the "Lance Armstrong talks about the
Stage 9 Beloki Crash, Stage 9 Attacks, and Stage 8 at Alpe d'Huez"
video replay on the oln site.

Stergios

Sheldon Brown wrote in message ...

I'm very sorry that Beloki was injured, and wouldn't normally want to
criticize him in a public forum like this, if it weren't for my belief
that this crash offers a valuable lesson to all cyclists on the dangers
of inappropriate use of the rear brake.

Again, for those who tuned in late, here's my article on this important
topic. It might save your life: http://sheldonbrown.com/brakturn.html

Only problem with this is that locking up the brakes is a reflexive
response to an emergency. Cars, motorcycles, bicycles- when you get
scared you slam your foot or hand down and lock 'em up, not subject to
the intervention of your higher brain which presumably knows better.
Reading articles is a small part of it. Practicing what you read is
the rest.

Ironically, your article suggests that rear braking may have been
appropriate if the corner was slippery. (I'm not sure I agree with
this usually- the front still will give better braking as long as the
brake is properly modulated, unless there is no grab at all from the
front tire, in which case you are porbably going down anyway.) Also,
I'm not sure that 10/10ths riding downhill with the yellow jersey on
the line is where you would dispense with the rear brake altogether,
since even 5% rear braking is of value at that point, but you may very
well be right that he could have gotten through with only the front.
Maybe rear brakes should be banned.

Beloki's problem was probably pushing to hard, to the point where his
reflexes took over, but don't forget also that on a fast, steep,
perhaps slippery downhill, with powerful brakes the rear tire is even
less loaded than usual and relatively easy to lock up. My guess is
that he slammed on both brakes. The two factors may have played into
each other: when his wheel locked up his reflexes kept it that way.
Conversely, Armstrong's dirt experience may have conditioned his
reflexes for the correct braking response.

The problem is to have a braking system that functions properly under
reflexive *and* higher brain control. ABS does this as long as you
learn to slam on the brakes until the ABS kicks in (and not let up
when it does, which seems to also be a reflexive response in most
people) which is the opposite of how you control emergency braking in
a non-ABS car. I could never understand how motorcycle ABS which was
auto-disabled when cornering could work properly- you would have to
develop different (reflexive) braking responses for cornering and
straightup riding.

JP

(Qui si parla Campagnolo) wrote:

Pix have shown it to be a clincher....

So there you have it - avoid riding clinchers in the mountains... ;-)

I watched the clip several times in slo-mo, and think it may have
happened a little differently. Here's what I think happened.

The rear tire slid out on slick tar under braking (Beloki
countersteering to keep the bike up). The wheel rotated, constantly
bringing a fresh, unslick portion in contact with the tar. Suddenly
the wheel moves OFF the tar, and the tire hooks up with the road
surface. The lateral force of this both peels the tire off the rim
(at which point the tube explodes), AND vaults the back of the bike
violently up and to the right. There was no way in the world anyone
was going to stay up at that point.

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

"Mark Hickey" wrote in message
...
(Qui si parla Campagnolo) wrote:

Pix have shown it to be a clincher....

So there you have it - avoid riding clinchers in the mountains... ;-)

I watched the clip several times in slo-mo, and think it may have
happened a little differently. Here's what I think happened.

The rear tire slid out on slick tar under braking (Beloki
countersteering to keep the bike up). The wheel rotated, constantly
bringing a fresh, unslick portion in contact with the tar. Suddenly
the wheel moves OFF the tar, and the tire hooks up with the road
surface. The lateral force of this both peels the tire off the rim
(at which point the tube explodes), AND vaults the back of the bike
violently up and to the right. There was no way in the world anyone
was going to stay up at that point.


Take a look at the following closeup and tell me those are clinchers.
http://www.velonews.com/tour2003/tec...es/4514.1.html

Look exactly like Campy Hyperon carbon tubular wheels to me.
http://www.campagnolo.com/pics/cerchio_carbon.jpg

The crash shot makes it look sorta like a clincher, but my money says it's
either the tubie's base tape you're seeing or maybe a double-sided tape/glue
alternative like TUFO sells. Either way, I agree about Beloki's chance of
not crashing when the rear tire let go. No hope; shame he didn't luck out
and lowside it.

SB