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a mtb question for mechanics(3 posts)

a mtb question for mechanicsDog
Oct 25, 2002 11:05 PM
I've recently upgraded to a FRM crank and chainring combo. from a XT. After installing the whole set up-including new chain I find that it refuses to shift properly to the small ring. The chainsuck is horrible too. Ok, so I put on a new front derailluer and this helped on the flat but uphills, the same problem. The BB length is the same. So I put the XT cranks back on and now find the same problem. WTF? the only differnce is I'm using a new chain. My only idea is my frame's a little tweaked and the old chain had more play allowing it to shift to the granny gear easier..Any ideas?
chain may be too short? check cable tension?(nm)merckx56
Oct 26, 2002 6:34 AM
Excellent questionspookyload
Oct 26, 2002 9:17 AM
When I get chain suck, the first thing I look at is chain lube. That is way too obvious here though. The shifting problem is probably attributed to improper front deraileur set up. Make sure you adjust the low gear set screw before installing the cable. Next make sure you don't set the cable tension too tight or the front deraileur won't throw back far enough. Also make sure the inner plate of the FD is parallel with the big chainring not the outer surface of the FD, this does make a big difference. The FD won't throw it far enough if it is angled in or out too much. Another thing to check with is if the FD is set too high. There should be around a 2mm gap between the teeth of the big chainring and the bottom of the FD cage. If it is too high it won't shift right either.

As for the chain suck...check for stiff links. The easiest way to do this is to freewheel the crank backwards and see if the rear deraileur cage moves fore and aft while you are doing this. As it is moving you are seeing the stiff links. Is there any chance you went from a standard crank to a compact crank? All of these problems are very common to that situation.