i would really appreciate a bit of wisdom. i have built a new frame with an old xtr triple chainset with middleburn rings, a 11 to 34 cassette and an xt rear mech.

everything works perfectly on the stand and seems well set up, the chainline is good and all gears work perfectly on the trails except when under pressure in granny ring and the 28 – 34 cogs.
under pedal pressure there is a constant clicky noise. its hard to know what’s going on, it feels like maybe the rear mech is jumping slightly? or is there slight chainsuck in the small ring ?
i can’t replicate it on the stand. any ideas appreciated, thanks

Not enough B screw, jockey wheel fouling cassette?

APF

Chain running through rear deraileur incorrectly? No idea why i thought of this…..ahem.

Loose/wonky mech hanger?  Mech tight on hanger?

thanks guys, maybe the B screw? although I’ve tried to set it correctly.

Did you put a new chain on it? If so, probably that. Install the old one to rule out/in.

Stiff chain link?

B screw would be my first port of call too. What’s the frame? HT or FS?

Chain length if the latter when suspension is compressed?

ok so, i think I’ve been a bit dopey. I changed a running gear that was running perfectly from old frame to new, that’s why I didn’t think of the chain. just tried a new chain and problem solved, the old chain was well stretched!
now need a new cassette to complete the process.
thanks for all the help, yes, I’ve previously managed to thread the chain through the mech incorrectly, set the B screw wrong, etc etc.
just a test ride now then off to Romania for a week of bike packing, happy days!

thanks again

Just an update. Not the mech, not the cassette, not the B screw. It was actually very slight chainsuck. I didn’t think I used the granny ring that much to wear it, it’s a middleburn but probably 10 or 15 years old! Anyway new chain ring now running sweet as a nut!