michael roger's tire peeling off

bicycle_disciple said:

On stage 8 of the this year's tour de france, australian michael
roger's from the t-mobile squad had a spectacular crash along with
david arroyo who went over the safety rails and plunged into some
trees. Sad for Rogers, who simply lost the tour right then and
there... a more spectacular event from a mechanical standpoint was
Roger's rear tire peeling off due to the crash... or maybe its what
caused it.. considering that he's a good descender.

How on earth did this happen? Chris Boardman suggested on ITV that it
must have been the severe heating of the black rims that somehow
caused it. But no one for sure knows what happened except Roger
himself. Afterall. he was the one to crash first, so perhaps was it
the sidden braking and the friction + the hot road that somehow
stretched the bead?? Some expert please explain this phenomenen to
me. I took a look at the crash pictures on google, but I can't make
out the wheels he was riding nor the tires (clincher or tubular) at
the time.

Funny that I saw no discussion of this incident here.

B.D
http://cozybeehive.blogspot.com

I don't know what happened either, but beads don't stretch. They are
either steel wire or Kevlar. It is very unlikely that a bead would
break, and even if a bead is cut in several places the pressure will
hold it all together, kind of.

It is possible that he was riding tubulars and they can creep if there
is enough heat to cause the glue to fail.

--
Ted Bennett

In article
<[email hidden]>,

bicycle_disciple said:

On stage 8 of the this year's tour de france, australian michael
roger's from the t-mobile squad had a spectacular crash along with
david arroyo who went over the safety rails and plunged into some
trees. Sad for Rogers, who simply lost the tour right then and
there... a more spectacular event from a mechanical standpoint was
Roger's rear tire peeling off due to the crash... or maybe its what
caused it.. considering that he's a good descender.

How on earth did this happen? Chris Boardman suggested on ITV that it
must have been the severe heating of the black rims that somehow
caused it. But no one for sure knows what happened except Roger
himself. Afterall. he was the one to crash first, so perhaps was it
the sidden braking and the friction + the hot road that somehow
stretched the bead?? Some expert please explain this phenomenen to
me. I took a look at the crash pictures on google, but I can't make
out the wheels he was riding nor the tires (clincher or tubular) at
the time.

Funny that I saw no discussion of this incident here.

B.D
http://cozybeehive.blogspot.com

Not especially mysterious. The same trick can be seen played by
ill-fated Joseba Beloki in 2003:

http://video.google.com/videoplay?docid=-5923038280471012988&q=beloki+cra
sh&total=4&start=0&num=10&so=0&type=search&plindex=0

That video isn't very clear, but at :30 you can just see Beloki's tire
coming off the rim, apparently as a result of his rather dramatic rear
wheel fishtail immediately beforehand.

These are tubular tires, and they can roll off the rim during a really
violent crash. Even clinchers can. Rogers was almost certainly riding
tubulars, the choice of most (but not all) pro teams, and especially so
when carbon rims are involved.

The tire may have rolled due to heat or the crash may have precipitated
it. I think in most cases though, the crash (and attendant extraordinary
side-loads) is what pulls tire free from rim, as appears to have
happened in Beloki's crash.

Beloki has not been the same rider since.

--
Ryan Cousineau [email hidden] http://www.wiredcola.com/
"My scenarios may give the impression I could be an excellent crook.
Not true - I am a talented lawyer." - Sandy in rec.bicycles.racing