… on the drivetrain, seems to only be one per revolution and I only feel it through my right foot. Bearings on the pedals (v12s) seem smooth, new XT cassette, chain, rings and bottom bracket is super smooth.

Any suggestions?

thats a tricky one – cos id suggest pedals. personally id just take everything off give it a clean – re-lube and rebuild.

Check the nut under the end cap is tight on the pedals.

I only have Wellgo V12 copies so I’m not sure if they’re exactly the same as real V12s, but there must be something equivalent.

If the bolt is even the tiniest bit loose, despite having smooth rotation you’ll get knock-knock-knock…

Haven’t ever actually stripped the pedals so I will give that a try later, cheers.

Possibly a loose crank?

Loose chain ring bolts, does it only do it on one ring?

Once per pedal rev can only be related to cranks really, so either pedal bearings, ring bolts/damage to the teeth, or BB bearings. Assuming you dont have bent/damaged cranks that catch the frame, and assuming its not a full sus where your pedal bobbing makes the sus clunk with each bob.

Any chance you could have bent the pedal spindle?, this you feel when pedaling but maybe not when your examinijg it

just stripped pedals and they are as new, no play or bearing probs with BB or cranks and chainring bolts all fine. It seems to run with a rather rumbling drivetrain which a bit of tlc and a lot of lubing seems to have subsided a little. I think I have tried most or all of the usual suggestions, was just hoping someone might recognise something a little out of the ordinary.