Ordered an 11-32 rear cassette but didn’t realize the 9150 rear derailleur maxes out at 30t per Shimano’s spec. Searched it and it seems like plenty of people have made 32t work, so I figured I’d give it a go and worst case I’d just get an 11-30 if it didn’t pan out. The spec I found as per this blog post had the gap as 14mm for 11-30t, and 6mm for 11-34t, so I just split the difference and called it 10mm.
After setting it up and adjusting the chain line, everything shifts great and nothing seems out of the ordinary, but wanted to get some feedback to make sure this B gap wasn’t too close (gears are set to large rear / small front). If I run this, are there any concerns I should be cognizant of, e.g. wear on the rear derailleur spring, etc.? Front chainrings are 50/34, if that’s relevant.
by thejackamo1
1 Comment
On road bikes I like to adjust the b-gap by ear. Back it off until you hear the chain/cassette/jockey wheel rubbing, then add b-tension until it goes silent.
You want enough of a gap that there is no interference, but as little as possible to keep the shifts as crisp as can be.
I save all the careful measuring for full sus mtb setups.