Bicycle Mechanics - Chain keeps falling off
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I have a new Cannondale Syapse Carbon 2, front ultegra, compact crank, rear dura-ace, 12-25 cassette. No matter how much I adjust the front derailleur, to the point it rubs even when on the third largest rear cog, when I shift onto the largest rear cog and pedal hard the chain slips off the front. The LBS is baffled. Because of the suspect origin of the bike (too long a story) there is no warranty. Please help!
11-02-06, 02:50 PM
this is a 10sp setup, right? or is it a 9?
has the LBS actually looked at it, or did you just talk to them over the phone?
any stiff links? can the bike go into big-big?
Could you tell us what specifically you have tried? How did you adjust the derailleurs?
Is the FD at the right height for a compact crank?
The bike has a 10 speed cassette. I've played with adjusting the inside stop on the front derailleur. So far have only talked to the LBS. The chain is brand new. Doesn't seem to have any stiff links. It doesn't slip off on the bike stand, only under load. The front derailleur was already on the bike when I took it out of the box. The LBS didn't change the height. How do I know if it is at the right height?
11-02-06, 03:53 PM
the outer cage should be 2 - 3mm above the big ring when positioned over it. 90% of bikes that come from shops have the FD too high.
what kind of cranks?
Cranks are FSA carbon (Cannondale Si). Height of the derailleur looks good.
The rim of the derailleur must be parallel with the ring, too. It's fairly easy for clamp-on FDs to get knocked out of alignment.
Also, you said it slips off the big ring. That would imply that the outer limit needs adjusting, but check the alignment first.
Dustin, you were right. A closer examination of the chain (brand new shimano) showed a pin starting to work it's way out. The LBS couldn't find a new Shimano pin, I didn't think about just bringing the bike home and pressing the pin back myself, and really, I wanted a chain with a removable link. So I bought an SRAM chain and now the derailleur just purrs.
Thanks for all the help.
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