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Discussion Starter · #1 ·
My problem: when sprinting and applying lots of torque while in the 53x12, my chain slips off the chainring (to the outside). My frame is a Giant TCR composite with a compact crank. I am 140 lbs.

I think I might be flexing the frame, or the crankset/chainrings, or both. Anyone have any suggestions for a fix -- aside from buying a new frame?

Thanks.
 

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Adjust FD

It sounds like your front derailleur upper limit screw needs to be turned in a bit. It should be set so that the cage is just past where it would rub on the chain. Also, you might consider changing the angle of the cage relative to the chainring, possibly moving the back of the cage closer to the frame (rotate the derailleur slightly clockwise on the seat tube). Also, you might check to see how much wobble you have in your chain rings - that could be part of the problem.

BTW, congratulations in being able to sprint in a 53/12 - that should be over 37 mph!
 

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Kerry Irons said:
BTW, congratulations in being able to sprint in a 53/12 - that should be over 37 mph!
It's even more impressive on a compact crank! Mine doesn't even have a 53. I kid, I kid ... Kerry's right, adjust the FD limit screw.

Cheers,
Ari
 

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chainring teeth

Also, if it's a consistantly reproducible problem, check your chainring teeth. Happened to me once - turned out that I had a very slightly bent tooth that was causing the chain to ride up and eventually off the ring to the outside.
 

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Discussion Starter · #5 ·
oops, I meant 50x12

For the record, I'm not sprinting per se, just doing powerstarts and strength exercises.
 
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