What caused Andy's rear wheel to pop up?

[Ninety5rpm]

You can see Andy's rear wheel pop up at about :08/:09 in this clip:

www.youtube.com/watch?v=HP9OR-Pz2Yk

What would cause that? Would the chain slipping off do that? I don't think so. Did he happen to hit a bump? If so, why didn't his front wheel pop up first?

If he's pulling up with his clips and suddenly the chain slips off, I would expect the "pull up" on the rear wheel to lessen, not increase.

Can anyone explain this or at least speculate as to what happened?

 

[MacRoadie]

You can see Andy's rear wheel pop up at about :08/:09 in this clip:

www.youtube.com/watch?v=HP9OR-Pz2Yk

What would cause that? Would the chain slipping off do that? I don't think so. Did he happen to hit a bump? If so, why didn't his front wheel pop up first?

If he's pulling up with his clips and suddenly the chain slips off, I would expect the "pull up" on the rear wheel to lessen, not increase.

Can anyone explain this or at least speculate as to what happened?

I'm having a hard time with the whole "missed shift" idea to be honest. Schleck is riding steady tempo, eyes focussed ahead, and really isn't in a spot where a gear shift makes any sense, certainly not one that would contemplete changing chainrings. Maybe dropping down a cog, but anyone ever dropped a chain doing that?

Look at 00:47 of the video. Both hands wrapped around the hoods, no fingers on the levers. He wasn't shifting.

 

[riobonito92]

Speculation 1:

He tried to multiple change gears at the back and this caused the rear mech to jam just as he puts in a big effort - and that is what throws the chain - and he reacts by putting on the front brake.

 

[patricknd]

i think the guy on the grassy knoll had something to do with it.

 

[cyclopeon]

Maybe this.

The spacing between the inner chainring and the frame are really tight on some of the new bikes, such that one cannot manually get the chain into the gap! So when the chain dropped, I think it jammed momentarily between frame and chainring, and with the force on his pedal at the time the chain pulled the wheel up (his weight being more to the front of the bike helped too).

I'm rather surprised that the chain free'ed up right away though.

 

[RedsharkO]

Something similar happend to me 3 weeks ago and my rear wheel also pops up. When the chain slips down, it get wedged into the small chainring and the BB shell, so the pedal stroke is not more transfered by the chain to the sproke and al the legs torque is applied to the BB shell and pops up the bike.

 

[riobonito92]

I will correct myself - I don't think he touches the brake - but I still think a jamming rear mech is possible.

 

[MacRoadie]

I will correct myself - I don't think he touches the brake - but I still think a jamming rear mech is possible.

Except that if you watch 00:44 though 00:48 of the video, his hands only move to the left lever AFTER the slip. Nowhere near them before. He wasn't shifting.

 

[erader]

You can see Andy's rear wheel pop up at about :08/:09 in this clip:

www.youtube.com/watch?v=HP9OR-Pz2Yk

What would cause that? Would the chain slipping off do that? I don't think so. Did he happen to hit a bump? If so, why didn't his front wheel pop up first?

If he's pulling up with his clips and suddenly the chain slips off, I would expect the "pull up" on the rear wheel to lessen, not increase.

Can anyone explain this or at least speculate as to what happened?

chainsuck. you'll note it happened when schleck attacked so i've got to go with sloppy shift.

you'll also notice how quickly contador passed him....he probably thought andy wanted to play trackstand again and was having none of it .

erader

 

[Steel4Ever]

His finger.

 

[Steel4Ever]

i think the guy on the grassy knoll had something to do with it.

Can't be me. I mow my knoll once a week.

 

[Big GMaC]

Is on the button?

 

[131313]

Except that if you watch 00:44 though 00:48 of the video, his hands only move to the left lever AFTER the slip. Nowhere near them before. He wasn't shifting.

I have to disagree. Looking at the clip you posted, in high res, it looks to me like he shifted, probably from the 12 to the 11, while in the small ring. His right hand appears to move right before.

Regardless, he was riding way too crossed up (another photo still shows that). The chain caught the big ring, had momentary chain suck and that's what popped his rear wheel up and then tossed his chain.

He should have put it in the big ring before his attack. Standing and sprinting in a 39x11 just isn't a great idea.

 

[Dr. Maserati]

Easy - the motor kicked in.

 

[Big GMaC]

Easy - the motor kicked in.

Was it a VtEC?

 

[tigger509]

Andy knows how to shift, Contador knows how to shift better. Andy likes deep fried turkey.. that must be his secret!

http://www.youtube.com/watch?v=UzPq0hDdDhs&feature=related

 

[Hillavoider]

Karma jammed the rear deraileur and fabian was too far away to neutralise and frank had already fallen off his bike, so.... whatever he did when he changed gears before the attack was not completely in place, chain jumping across two gears, then the chain gets tight and the deraileur gets caught up and the back wheel jumps. bad gear down change got him.

 

[riobonito92]

I have to disagree. Looking at the clip you posted, in high res, it looks to me like he shifted, probably from the 12 to the 11, while in the small ring. His right hand appears to move right before.

Regardless, he was riding way too crossed up (another photo still shows that). The chain caught the big ring, had momentary chain suck and that's what popped his rear wheel up and then tossed his chain.

He should have put it in the big ring before his attack. Standing and sprinting in a 39x11 just isn't a great idea.

So he was simultaneously changing from the 12 to the 11 AND from the 39 to 53 while out of the saddle going up hill in order the accelerate? Perhaps - and I don't have a good enough video to see this - he is changing from the 39 to the 53 and also from the 12 into about a 16 - that would probably jam the chain.

 

[bobs nob]

chainsuck. you'll note it happened when schleck attacked so i've got to go with sloppy shift.

you'll also notice how quickly contador passed him....he probably thought andy wanted to play trackstand again and was having none of it .

erader

+1 to the bolded. This was my first reaction when I tried to imagine how AC would have perceived it, "This kid is nuts and he wants to play chicken again."

maybe next time AC can watch the race in his air conditioned apartment and decide what to do under the circumstances.

 

[editedbymod]

Without knowing it I think Andy just the invented the best way to stop doping.

Any rider banging over 500 watts on a climb their bike is programmed to drop the chain. Job done. Instant 30 second penalty whilst you put your stinking chain back on.

 

[Anonymous]

You can see Andy's rear wheel pop up at about :08/:09 in this clip:

www.youtube.com/watch?v=HP9OR-Pz2Yk

What would cause that? Would the chain slipping off do that? I don't think so. Did he happen to hit a bump? If so, why didn't his front wheel pop up first?

If he's pulling up with his clips and suddenly the chain slips off, I would expect the "pull up" on the rear wheel to lessen, not increase.

Can anyone explain this or at least speculate as to what happened?

Aliens .........

 

[embankmentlb]

Andy chose SRAM! He will never forget it...

 

[BroDeal]

Andy chose SRAM! He will never forget it...

Astana is using SRAM also...

As to what happened to Shrek, in the high tech we call this "user error."

 

[MacRoadie]

Astana is using SRAM also...

As to what happened to Shrek, in the high tech we call this "user error."

In the Campy world, we just call it "SRAM".

 

[StyrbjornSterki]

Maybe this.

The spacing between the inner chainring and the frame are really tight on some of the new bikes, such that one cannot manually get the chain into the gap! So when the chain dropped, I think it jammed momentarily between frame and chainring, and with the force on his pedal at the time the chain pulled the wheel up (his weight being more to the front of the bike helped too).

I'm rather surprised that the chain free'ed up right away though.

You're exactly right. I've watched the video frame-by-frame and I'm convinced that's exactly what happened. When the wheel went airborne, his chainrings flung the chain almost immediately. I think the slack in the chain and the impact of the landing un-jammed the cogset.

I'd thought about chain suck, too, but the lower chainline remains taught until the instant the rear derailleur moves, indicating the point at which Andy attempts to shift. Then it gets a little slack but it's hanging off the front of the chainring, not wrapping around the back. Next thing, the wheel hops.

The first event definitely was the chain jamming in the cogset. The rest will have to wait until that Zapruder fella gets his film back from the drug store.