Is this likely to be a problem? Herself is very interested in buying a niner RLT9 but she uses short cranks and niner don’t recommend using non external bearing chainsets with the bio centric. Any suggestions?

How short? Is 165mm too big?

She’s got existing 155s from her Madone which got t-boned last Thursday, seems a shame not to use them.

My guess is that tightening the NDS cup will be trying to pull the sides of the bb apart and might distort it?

I can imagine that running old-style cup-and-cone bearings might be an issue.

But… oh…ah… but if you think about how a, say, UN51 BB fits in a frame, it’s actually by PUSHING the two sides apart. That’s no issue in a conventional BB, but when the BB is two seperate halves – that have to be clamped together to clamp in the frame – yeah – I can see that would be a problem.

A square taper BB that has a LOCKRING on the outside, rather than a cup that presses onto the bearing unit should be OK – as that’s “pulling”…

Thanks brant – something like the spangly TA axis do you reckon?

I think so… but I’d check with Niner.

Update – just had a response to my email, from niner’s Director of Fun, that the TA AXIX will work with the Bio-Centric 30 BB.