Road Gear

Technical FAQ: Rear drop out variation

Why does my rear derailleur pinch my chain on the largest cogs?

Follow up regarding Jim’s jockey wheel pinching the chain to the cassette in the large gears:

I built a new Mongoose Ti frame up with all XTR components and had the same problem. No amount of B-screw adjustment would fix it .I measured the distance from center of axle to center of derailleur mounting bolt on my bike and on others. There was a surprising amount of variation. I spoke to Shimano and they said that in spite of published build specs, many manufacturers did not comply.