Just fitted the Hope 40 T rex to a used 11-36 xt cassette.
The cassette is fine when used as 11-36 but after I’ve tweaked the b tension screw and put the 40t on it skips like ****.
Any ideas please?
It’s a new chain, jockey wheels aren’t that worn nor is the cassette.
The issue seems to be with having the b tension screw in so far to get the clearance.
I’m using an xtr clutch rear mech.

It’s a new chain, jockey wheels aren’t that worn nor is the cassette

Have you tried the new chain on the cassette in 11-36? May well be the new chain and part worn cassette causing the issue. I’ve heard folks claiming it should be ok but I’ve never has a new chain work on even a nearly new cassette.

Tough to say without seeing it but you say the cassette is used but not worn…could be this plus as you say having to max out the B tension screw.

+1 on the worn cassette.

Adjusting the b screw has probably highlighted the issue due to having less less chain wrap.

Thinking about it, having the b screw adjusted all the way in could lead to premature cassette wear/slippage.

With the 11-40 it slips in 11/13/15.
I’ve put the 11-36 back on and adjusted the b tension screw and no slip.
Could be the rear mech hanger slightly out of line so I’ve ordered a new one.
Maybe I should splash out on a new cassette.

It won’t be the hanger.

You need to try it with the cassette only but b tension screw set for 42T.

Then replace the cassette 😀

I had exactly this with a 42t one up, slipped in 11,13,15 changed the chain but it wasn’t that, changed the cassette and all is good again.

Prize goes to cynic-al!
Changed the cassette and tweaked the b tension screw so the cage just clears the 36 sprocket and all is good.
Thanks folks!

I set-up my bike 1 x10 with a OneUp 42 & 16 tooth conversion. Cassette is lightly used, chain is new, & rear mech is XT Shadow+ long cage.

The shifting is good & I had to remove the B screw plastic washer to get the screw in far enough to get the mech to clear the large sprocket.

My problem is chain slippage in the smallest 3-4 sprockets. I would imagine this is due to a new chain on used cassette but the chain slips on the new 16T sprocket.

Any suggestions to solve the slip?