Hi, I've currently got a shimano crank-set with shimano 6-speed rear and front derailleur. Is it possible to use a different make if I replace the crank-set, for example if I brought a suntour crank-set? thanks for any advice you can give. Also my current crank-set/drive-train has a wobble in when I rotate the peddles, it's not loose or anything, it just doesn't rotate in a straight line, has a slight wobble to it, is there a way to fix this? thanks.
You can probably use just about any crankset with a 6 speed set up. Many newer cranks, especially higher end ones, are made to sit in closer to the bike so you might run into a situation where you need an longer bottom bracket. But you don't need to worry about matching brands.
The wobble could be a couple things. If just one chainring wobbles, it is probably the chainring itself that is bent. You may be able to bend it back straight. If both chainrings wobble identically, it could be that both rings got bent. But more likely that either the crankset itself is bent or that the axle (spindle) of your bottom bracket is bent. To tell which, you could try pulling the crank and put it on the other side of the bike for a test. If it still wobbles on the left - bent crank, if straight - bent spindle. Finally you might try just tightening down the crank, it could be coming loose and not sitting straight because of that.
The are actually 4 possibilities
1. Bent chairing as noted above
2. Crank/spindle interface - try removing the arm and reinstalling after rotating 90 degrees at a time to find the best position.
3. Bent spider arm - what Dave is calling a bent crank.
4. Bent spindle - rare, only one that require a replacement
Okay thanks for your replies, I will try those suggestions out, thankyou.