Finally figured out my chainline was off after a customer's comment

A guy brought in his fixed gear with a clicking noise I could not find for the life of me. I checked the bottom bracket, the chainring bolts, everything. He casually mentioned it only happened under heavy load, like climbing the hill on 5th Street. That made me put it on the stand and really crank the pedals hard, and sure enough, the chain was jumping a tiny bit on the cog. My chainline was off by maybe 3mm because I was just eyeballing it for years. Anyone have a favorite tool or trick for getting chainline perfect on track bikes?

3 comments

3 Comments

erickelly22d ago

I use a cheap digital caliper from Harbor Freight. I measure from the locknut face on the rear axle to the middle of the cog, then match that distance from the bottom bracket shell to the chainring teeth. It gets me within half a millimeter every time, which is close enough for no more weird clicks.

fiona_kim9721d ago

Frame the rear wheel between your knees next time, it's janky but works.

adams.vera21d ago

Truing stand is the way to go if you do it more than once a year... Park Tool TS-2 or even the cheap knockoff from Amazon. I put my wheel on, spin it, and use a zip tie as a pointer to find the high spots. Takes maybe 10 minutes once you get the feel for it. But for the chainline thing... nobody mentioned using a first gear cog as a reference. If you line up the chainring with the middle of your cassette, not the specific cog you use most, you get less noise across all gears. Found that out by accident when I swapped cranksets one time.