So I just transferred a drivetrain from one bike to another, it was working perfectly on the old bike but on the new bike the chain fouls the rear mech when shifting up or down the larger sprockets.

Cassette is a 10spd sunrace and the mech is a XT M786 with a radCage fitted, mech worked perfectly on the old bike with the same cassette range and has never taken a knock. I also have the exact same setup on another bike which works perfectly

Hanger alignment is perfect as I just checked it with the proper tool.

Any ideas what could be causing this?

perhaps the b screw not in far enough? Can we have another pic, pulled back of the shebang and the right way up?

Is this a Direct Mount rear mech that you’ve taken off a compatible frame and now tried to mount on a non-Direct Mount hanger?

Seen that before on frames with out of spec hangers (shelf too high) or where the b-link has been clamped too high, so that the tab on the link is not leaning on the shelf on the hanger. Loosen the mounting bolt and try to push the b-link down and ensure the tab of the link and the shelf on the hanger make contact. If it doesn’t move, then perhaps worth “correcting” the shelf position on the hanger with a file….

Is it tthe chain off the other bike? If so and new bike has longer stays it’ll be too short.

Both standard mount, 2013 Mega TR and OnOne 456, b link used in both cases, b tension screw doesn’t seem to have an affect on the clearance between the cable clamp arm and the cassette. Will get more pictures shortly.

Hanger shelf and b link tab are in contact with each other, it’s a new chain and has been measured with the biggest to biggest plus a link method.

More pics.

Goatlink?

Is this a Direct Mount rear mech that you’ve taken off a compatible frame and now tried to mount on a non-Direct Mount hanger?

This is a good shout

Both definately standard mount, and the b link is being used.

Sorry missed the reply earlier

sillyoldman has it.

+ 1 sillyoldman

similar here:
http://singletrackworld.com/forum/topic/drivetrain-clearance-issues-doing-me-nut-anyone-use-a-goatlink

Well, on that PP frame the B-knuckle was clearly in the wrong position, on this one it’s horizontal, which is more or less correct.

Was the hanger on the other bike aluminium? (i.e thicker?) The steel dropout/hanger is pretty thin, so the derailleur sits a bit closer to the cassette; you could add a washer/spacer between the B-knuckle and the hanger to space out the derailleur a bit.

Cheers guys, I’ll check it against Shimano specs later and get the file out, looks like the Goat-Link may help if that doesn’t fix it.

An update for anyone with the same issue, I filed the hanger tab down a bit but didn’t want to take too much off, so then filed over half the mech tab off, now shifts perfectly, thanks for the help all.