Comments on: Technical Q&A with Lennard Zinn: Why did Schleck’s chain come off?

By: rfeagan

rfeagan — Tue, 24 Aug 2010 01:17:35 +0000

So, has anyone here cut off the “extended loop” from their Sram Red/Force/Rival rear der with a dremel? Why not?

By: rfeagan

rfeagan — Mon, 23 Aug 2010 21:17:35 +0000

So, has anyone here cut off the “extended loop” from their Sram Red/Force/Rival rear der with a dremel? Why not?

By: WesTaylorable

WesTaylorable — Thu, 19 Aug 2010 22:01:40 +0000

It was a SRAM, next question.

By: oldclimber

oldclimber — Tue, 27 Jul 2010 00:54:37 +0000

Glad to see someone offering a critique of the "Shift that Lost the Tour". It is irritating when apparent mechanical shortcomings are sanitized out of reports, and we're left with nothing but cliched superlatives on every product.
Still, it's very interesting how ubiquitous SRAM is in such a short time. I'm curious as to how noone else, especially Alberto, has had anything comparable to cope with, given a near-identical bike, etc. Maybe too long a chain? I live how the gumbies here are posting how superior they are to Andy Schleck, because you guys know how to shift? He and all the other Tour riders have probably shifted 1000 times more last year than you guys in your life. Read the new PR bs re:SRAM 2 x 10 "even extreme crossgearing is useable" and you realize the manufacturers are claiming all their stuff works perfectly forever.
Why sprinters who max out every aspect of stress on frames and drivetrains seem to have had no such issues, then, as if in ironic epilogue, Schleck appeared maybe to be demoing to Contador how the problem occurred, on their "faux breakaway" on the final day, in ultra-slo-mo, when something apparently DID go awry again? Wassup with THAT? Sabateurs?
Whatever the final analysis, I predict 12 certainties for his new team next year:
1. That team mechanic will be gonzo.
2. They won't be riding SRAM
Any bets?

By: inwarresolution

inwarresolution — Sun, 25 Jul 2010 20:49:39 +0000

You know, I thought the same thing, but then I realized that Vino was only racing to mark Andy, and if Andy slowed, Vino was going to slow. Vino's move was defensive, and he had no intentions of passing Andy under any circumstances. I don't think Alberto's move was the act of a classy champion.

By: Boofungus

Boofungus — Fri, 23 Jul 2010 17:17:18 +0000

I think some of you need to go back and look at the video. As the chain comes off, Vino is looking BACK at Contador, and he is directly between Cont and Schlek. No way either of them saw the chain come off. Also, Schlek is still PEDALING as both pass. Not a racer on this planet who wouldn't have gone, and gone hard. Now, after he hears on radio about the misfortune we can all debate about whether he should have sat up, but most of you have poorly analyzed the chain drop.

By: Boofungus

Boofungus — Fri, 23 Jul 2010 16:59:45 +0000

By: ExMachina1

ExMachina1 — Fri, 23 Jul 2010 15:22:52 +0000

OMG!!! SRAMs are throwing chains off left and right!! It's a SRAM chain-trowing extravaganza!!! Mothers, protect your children cuz there's a SRAM chain flying your way.Oh, to be back in the good ol' days when chains never dropped. Curse you SRAM.

By: ExMachina1

ExMachina1 — Fri, 23 Jul 2010 15:22:43 +0000

…

By: Bobby Gray

Bobby Gray — Fri, 23 Jul 2010 12:13:51 +0000

I really don't know why the Pros are riding that SRAM crap. And Crap it it is and always as been. The Chilli's of bike components. Perfect crap for the un-educated consumer.

By: Eric

Eric — Fri, 23 Jul 2010 05:23:07 +0000

Sorry to say but SRAM SUCKS!! they lost the tour for Andy .

By: christianride

christianride — Fri, 23 Jul 2010 02:53:12 +0000

Yes! I've been saying all along that Andy's mishap was due to SRAM's fault. I had my chain pop off like that during a climb on my SRAM Force. I thought it happened because it was Force, but to see that happen to Red means that SRAM needs to go back to the drawing board. Andy should be blaming SRAM for his Yellow Jersey loss. Fine, Alberto made a unclassy move but it is a race and something like that a bit of bromance will solve, but SRAM mech. problem that's really bad–like Toyota cars. I hope Andy seek out for Shimano or Campy sponsorship next time.

By: Peter Popp

Peter Popp — Thu, 22 Jul 2010 21:37:50 +0000

I've watched and re-watched it a bunch of times with TiVo in high def, and while I can't tell what caused the drop or whether Andy was shifting at the time, it's very clear in the shots after he gets off his bike that he is using a modified derailleur with Berner-style large pulleys. No doubt about it.BTW, what is the mechanic using to hold the chain in place when he's cleaning Andy's bike?

By: Anonymous

Anonymous — Thu, 22 Jul 2010 16:45:00 +0000

Looked like Contador was hanging on to Sammy, ‘The Great Descender’…… who was also a GC contender. I don’t blame him.

By: jackorion

jackorion — Thu, 22 Jul 2010 01:33:19 +0000

This is the second major chain mishap that has happened to Saxo sense switching to Sram. The first was last year when Fabian snapped a chain in a major classic. Now Schleck, does anyone know of any other incidents? I'm Jack Orion and I choose Campagnolo.

By: FrankDay

FrankDay — Wed, 21 Jul 2010 22:41:30 +0000

It is very difficult to explain how simply locking a rear wheel can cause it to jump several inches off the ground. Why doesn't it happen when one suddenly applies the rear brake with enough force to cause skidding (something I used to do everyday as a kid when I had a coaster brake)? Where are the forces coming from that would cause this? As I have thought about this I think several conditions have to be present to cause it.

It is really a fairly simple physics problem. There must be a sufficient torque around the center of mass to cause the rotation. Expalining where the forces originate that can cause enough torque to cause this is the problem. Here is my analysis.

The sudden locking of the wheel is a necessary but not a sufficient condition to cause wheel jump. Several other conditions have to be present together to see such a sudden large jump in the rear wheel. These conditions are:

1. the rider must be out of the saddle.
2. the rider must be attached to the pedals.
3. the rider must be riding at very high power or cadence or both
4. the rider should be pedaling in a circular fashion (that is, unweighting with some vigor on the back stroke (this is not a necessary condition but only contributes to the intensity of the lift)

To explain further,

1. The rider must be out of the saddle because this separates the riders mass from that of the bicycle. To lift the rear wheel does not require lifting the rider also. This substantially reduces the forces required to rotate the bicycle.

2. The rider must be attached to the pedals because that is a necessary condition to apply a torque that would tend to lift the rear wheel off the ground at the pedals.

3. Once the rider is separated from the bicycle by being out of the saddle and attached to the pedals the forces put on the pedals by the rider are also torques tending to rotate the bicycle. Pushing on the down stroke tends to push the front wheel into the ground and pulling up on the backstroke tends to raise the back wheel off of the ground. when riding normally, these forces are small because the pedals are moving away from the feet. But, when the wheel suddenly locks all of the muscular force (and momentum of the limbs) is suddenly transmitted to the pedals causing a large impulse force tending to rotate the bicycle. The downward rotation of the front wheel is resisted by the earth. But, only gravity prevents movement up by the back wheel. Coming out of the saddle also does one other thing. It moves the mass of the rider forward compared to the center of mass of the bicycle, putting more weight on the front wheel and making it easier to lift the rear wheel off the ground. If the rider is attached to the pedals the upward momentum and forces can lift the wheel off the ground if they are large enough.

4. Pedaling in circles simply adds to the forces on the backstroke (described above) tending to lift the back wheel off the ground such that the more one is doing the more likely the wheel will come off the ground and the higher the wheel would come off the ground.

The reason my back wheel did not jump off the pavement several inches when I locked up my rear wheel as a kid with my coaster brake (even if I were out of the saddle) is because I wasn't pedaling at the time and even if I were I was not attached to the pedals and could not apply any lifting force when the upwards moving pedal suddenly stopped.

Of course, I am open to other explanations as to what could cause this rear wheel jump I saw.

By: pyops

pyops — Wed, 21 Jul 2010 21:16:24 +0000

My friend Robert put SRAM on his new Trek, and not once but TWICE his rear derailleur locked up. One time it broke the chain a hundred yards before the finish of a lead out Rapha Ride on the Tour of CA Santa Cruz Stage. It twisted in and ruined his wheel as well, then snapped off.

The second time was on a descent, and his wheel locked, just like the 'bounce' you see with Schleck.

SRAM should revisit their design.

By: thenail

thenail — Wed, 21 Jul 2010 20:13:30 +0000

I'm running the full red group and when shifting from the large chainring on my red compact 52/34 to the small chainring with on a 25 rear cog I have had the derailluer rotate up and lock up the cassette. This has happened a couple times but I have never been on the pedal hard enough to throw the chain but it is exactly the same scenario.

By: DAMan

DAMan — Wed, 21 Jul 2010 18:23:19 +0000

I hope that SRAM paid you for these comments.

By: VeloJon

VeloJon — Wed, 21 Jul 2010 15:41:27 +0000

Schleck was using the Berner oversized jockey wheels in his RD which does not have the suspect loop described byu Lennard above. But even without the loop, the cage looks like it protrudes out the back more than normal. Could this have been part of the problem – these things are new and not really race-tested at this point. http://road.cc/content/news/19678-have-you-seen...