Seatpost comparison: Nimbus alloy vs. Nimbus CrMO

Weight of Nimbus alloy seatpost, 27.2mm x 400mm, cut to 350mm: 300 grams
Weight of Nimbus CrMO seatpost, 27.2 x 350mm: 450 grams

Just in case anyone ever needs this info, the CrMO seatpost lacks the convenient metric markings on the back, and in general doesn’t look as fancy, but it is 50% heavier. It is also supposed to be stronger. Only one way to find out…


It’s definitely much stronger, and if it does suffer fatigue, it will bend at the top bracket whereas the alloy one will snap as yours did.

Another thing that is different about the CrMO seatpost is that it’s a much thicker 27.2 mm than my 27.2 mm alloy seatpost. Getting it into the frame was such a workout that for a moment I thought I might have to return it. I did manage to remove it the other day, minus a bit of its paint, and put it back in later, but am not sure I will be strong enough to perform this feat again. I guess if I remove my wheel, I could use my broken seatpost as a sort of ramrod to push this one out next time…

EDIT: Brian, your 36er hopping, street and muni riding are incredible! While waiting for my replacement seatpost to arrive, I did attempt a bit of hopping on my 29 and was surprised how much I could do, but your videos are really inspiring.

So I finally managed to extract my new CrMO seatpost from the frame for a second time, but was dripping sweat by the time it finally twisted out.

This problem seems to have solved itself, though, because this time the seatpost came out un-scuffed but with almost no paint left on it. The paint, I think, was what had given it that extra thickness. Anyway, just FYI. If your seatpost ever gets stuck, this might be the reason.


Get the seat tube reamed to 27.2 at a LBS. No production frame is truly 27.2 out of the box.

Well, it was 27.2mm out of the box, at least before they painted it. Once the paint came off, it was a perfect fit! No reaming needed.

Yeh I have had massive problems with these CRMO posts on multiple unicycles.

Got one stuck in an old KH 29 once and had to be removed with lubricant and got them stuck in a KH20. Trying to get it out without lube literally heats up the neck of the frame with the twisting that is needed.

I think from memory the Impact frame may be an even tighter fit that the KH’s.