Is it a bio pace chainring? they are not round, but elliptical.
Or chainring is very slightly out. Loosen all chain ring bolts at same time then rotate, work fine now? Then tighten each one progressively whilst turning to ensure its centered, then fully tighten each.
Is it a bio pace chainring? they are not round, but elliptical.
Or chainring is very slightly out. Loosen all chain ring bolts at same time then rotate, work fine now? Then tighten each one progressively whilst turning to ensure its centered, then fully tighten each.