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question on chain ring spacing(5 posts)

question on chain ring spacinghavenoname
Jul 18, 2001 11:08 PM
If you are in the small chainring on a 2 chainring set, and in the second or third smallest rear cog, and your chain rubs on the larger chainring what might be the problem? Spacing? A thinner chain?

ChainlineMike Prince
Jul 19, 2001 12:23 AM
Or the distance between the center of your seat tube and the small chainring. Chainring spacing or the chain may cause the rubbing you describe, but this is unlikely (although worth checking as the fixes are simple, either new rings or chain). More likely your BB spindle puts the chairings too close to the frame which gets the chainline off. Without knowing what your setup is it's hard to diagnose, though. Perhaps if you can provide more detail (i.e. brand/model of crankset, chain and BB and whether all components are 8 spd or 9 spd) you will get a better answer.

Chainline is difficult to measure without calipers, so you may be better off having a shop check it. For reference, Shimano specifies the 9-spd double front chainline to be 43.5 mm.

Hope this helps.
Jul 19, 2001 2:06 AM
As a gross indication turn the crankarms so they line up with the chain stays measure from the inside of the arm to the chain stay, they should be basicaly the same for both sides. Adjust the posistion of the B/B if there is a corection to be made.
crappy mechanincs!!!!havenoname
Jul 19, 2001 9:44 AM
I can't believe the bike store!! The reason my bike seemed messed up is 'cause it was. The chainrings that I had installed were put on backwards, and the chain needed to have a link taken out, and the spacing was wrong!

Basically, the mechanic I had did everything wrong! Today I got a different guy who seems to know what he is doing. Jeez, how can they hire these guys?
There are so many bad mechanics because...peloton
Jul 19, 2001 7:45 PM
bike shops don't pay squat. You get what you pay for.

It's too bad really. Bike shops usually can't afford to keep good mechanics on staff. Too many people ordering mailorder, or not wanting to pay for maintainence. It seems any time that I see a good mechanic in a shop it's because he owns the place.