Join Date: Apr 2009
Location: New Rochelle, NY
Bikes: too many bikes from 1967 10s (5x2)Frejus to a Sumitomo Ti/Chorus aluminum 10s (10x2), plus one non-susp mtn bike I use as my commuter
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Start by finding what the actual chainline is. You can do this empirically by measuring from the chainrings to the downtube and adding half the diameter of the tube. Then compare to the standards
or to the cassettes chainline (distance from inside of dropout, subtracted from the dropout width).
You can also measure it directly by placing a straightedge (edgewise, not flat) on a secant against the outer chainring, and carrying it back to the cassette, then allowing for the offset to the center of the chainrings seeing where it compares to the center of the cassette.
Based on that, you can decide if you're best option is to move the cranks outboard, check rear triangle centering, increase chainring separation, or use a narrower chain.
An ounce of diagnosis is worth a pound of cure.
“Never argue with an idiot. He will only bring you down to his level and beat you with experience.”, George Carlin
“One accurate measurement is worth a thousand expert opinions”
- Adm Grace Murray Hopper - USN
WARNING, I'm from New York. Thin skinned people should maintain safe distance