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drivetrain problems(3 posts)

drivetrain problemstnbiker
Jun 11, 2003 4:25 PM
I have a few month old Spec allez cromo, and I seem to drop the chain frequently. It has a 105 crankset and cassette, with a SRAM chain. What could I do to fix this problem, without having to go to the shop?
re: drivetrain problemsLone Gunman
Jun 11, 2003 5:01 PM
I take it that when you say "drop the chain" it means that it falls off the small ring and onto the BB shell? If so, your front derailleur is out of adjustment. Of course the answer is adjust it. You could go to the shimano website and search for adjustment directions. The actual adjustment you need to do is not that difficult; shift down so that the chain is on the small chainring and the chain is on the big cog(23?25?) on the rear cassette. Unscrew the fixbolt of the FD cable. Discover which screw (one of 2 possibilities here) moves the FD cage to the right closer to the chain so that it is almost touching the chain(we are talking about as much as 1/2 of a revolution of the screw, small adjustments, just watch for movement of the inner cage closer to the chain). Pull your cable taunt and reattach the cable with the fix bolt. Try shifting big to little and see if that works. By the way, it is very hard to mess anything up if you do it in small increments. If it really gets bad, take it to the shop, it is an easy adjustment.
re: drivetrain problemsalmccm
Jun 11, 2003 10:12 PM
There's no reason to loosen the fix bolt or pull the cable. I'd try tightening (turn clockwise) the low adjusting screw about 1/4 turn. This will move the cage towards the big chain ring. Try shifting a few times and if it still falls off try another 1/4 turn. The low adjusting screw should be labeled L and should be closest to the frame.

Whenever you adjust the derailer and it is shifting well on the stand (or with someone holding the bike so the rear wheel is off of the ground) you should also double check it by riding and shifting. It will shift a little differently with tension on the chain.