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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Things flex, all things on all bikes.
If you were to take any bike and put it against a wall so it couldn't roll and stood on a pedal to tension the chain, you'd find the top of the chainring moves outward with respect to the FD cage.
The flexing can be in the crank, BB, chainring, or just as commonly at the base of the seat tube as the BB shell twists slightly under the load. It's 100% normal and unavoidable, though movement due to bearing play can and should be eliminated.
Usually this isn't a problem, because before using the highest gear at high pedal pressure most folks have already shifted to a lower gear moving the chain inboard a bit.
But, if you ride in outer/outer under high load, adjust the outer limit and cable tension to move the cage out far enough to clear. This may cause trim issues using the large chainring with more inboard rear sprockets, but unless your FD system allows trim is a decision you have to make and adjust for accordingly.
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”
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