Help me diagnose Taxc Neo 2T rhythmic thump or thunk

[C40_guy]

I have a two year old Neo 2T that has a rhythmic thump while applying pressure to the pedals.

Not quite sure where it's coming from, I've tightened/examined the obvious culprits. Before I start swapping parts, I'd appreciate some thoughts on where the source is most likely to be.

I *feel* the thump just after the top of the right pedal revolution, and only when pedaling with at least moderate pressure. I can't seem to replicate it by hand. It doesn't show up when turning the cranks lightly.

Configuration:

Trek aluminum frame
Record or Chorus bottom bracket
older Record carbon crankset with new Centaur chainrings
Old Look CX7 pedals
newish chain
new Chorus cassette
Record silver derailleur

Neo 2T with Raxles update (from new)

If I were to guess, I'd say it's an axle problem, either bottom bracket or pedal...possibly also the Neo itself...

It's not a metallic thunk, so I don't think it's chain related.

Everything is clean, no rust, lightly/occasionally used, no heavy efforts

Thoughts appreciated.

[reuben]

Can someone touch the rear axle, bottom bracket, etc., while you're pedaling in order to feel where the thump is most pronounced? Without losing any small body parts?

Alas, alack, my kingdom for third hand at the end of a long arm.

[glepore]

My first suspect is pedal bearings.
Doubt its the trainer as one rev at pedals doesn't equal one rev at cassette and its happening each pedal rev.
Had this recently on a newish build and turned out to be bad inner bearings (Time pedals with bearings replacing inner bushing).

[DfCas]

Isuggest you join the neo group on fb. There is a gentleman in England named Rich Webb who repairs these. There have been cases of the housing touching the magnets under load andcreating a noise.. there has also been cases of debris sticking to the magnets causing noise, which is more pronounced under load.

[C40_guy]

Originally Posted by DfCas

Isuggest you join the neo group on fb. .

Thanks...been a member there for a while and have posted the question there too.

This is a feel rather than a noise and I suspect a pedal (as mentioned above) or maybe BB axle rather than the NEO.

The thump is at the top of each right pedal stroke...

[Willy]

How about you put another bike (borrow one from a friend if need be) on the Neo to determine if it’s the bike or the trainer?

[C40_guy]

Originally Posted by Willy

How about you put another bike (borrow one from a friend if need be) on the Neo to determine if it’s the bike or the trainer?

Good idea. I might swap the right pedal first, then move another bike over to the trainer if the pedal doesn't do it. Swapping bikes is easier than identifying a crank/bb problem...

The cassette is mounted directly to the trainer, but the fact that the thump is felt every pedal revolution suggests it's probably at the front of the drivetrain.

I appreciate the input! It's helped me to figure out a plan of approach.