Avoid Nimbus Seat Posts

Unicycle(dot)com is sending out a bad batch of these Nimbus Alloy Seat Posts. That, or their photo is very misleading.

The image online:

What you actually get:

Why it sucks:

  • Strength is a function of diameter. A seat-post should not neck-down like this.
  • Sharp corners are stress-points. These welds aren’t great for that either.

Response from UDC after bringing it to their attention:
(paraphrasing here):

“Thanks. You need to pay to ship it back to us, then buy something else”.

So save yourself the hassle, and just spend the extra $5-$10 to buy a quality seat post.

Good luck and happy riding.


I’ve had good experience with UDC Germany so far, but that is just ridiculous. It looks like the robot welding the seatposts was setup wrong, and absolutely missed the bevel it was supposed to weld in. Clear quality control error that is not acceptable, and they should take care of.

EDIT: I have the seatpost pictured on top on my oracle, and it well… looks like in the top picture, so they did get it right in the past

Contact first your shop to solve the issue !

That’s what he did. From their (paraphrased by joshpit2003) response, they don’t want to recognize this as an issue.

I guess that confirms it’s a manufacturing defect. Thanks for the info.

I had ordered 2, and both showed up with the same defect. I reached out to UDC with photos and explanations. Since I was asked to pay to ship 'em back, I assume they consider the defect normal and these exact seat posts (or similar) will be shipped out to other customers.

Hence the warning.

I have to agree. I have three of those seatposts sitting around and none of them neck down like that. Mine are all the older model without the gusset-type thing at the top, but that shouldn’t change anything. The UDC web site has an unboxing video for the new version of the post, and it doesn’t neck down much.

So yeah, defective, and they should really take it back at no charge and quit selling that batch.

It is kind of hard to claim the part is structurally deficient just based on the external appearance. The strength at the smallest tube section is based on the actual diameter and tube wall thickness at that location. If the tube wall thickness is thicker at that point then is could be just as strong as a larger diameter tube with a thinner wall thickness.

It does look like most seat tube failures occur on the flat part that attached to the seat. I guess the only real way to say if it is a problem it to do some structural testing or just put it to use and see what happens.

Naw, I feel bad enough paying (return shipping) to do their Quality Control. I’d feel a lot worse if I paid (physically) to do their stress-testing.

I just purchased an Impact seat post for $5 more and peace of mind.

Impact is also Nimbus ;).

LOL. Doh!

Well, on a positive note: I can confirm the Impact seat posts are as-pictured and seem plenty strong.

Had some “perpendicularity” issues

Does your saddle seems “slanted” from left to right?
Then check the seat post mounting flange.
Mine was off a bit, so much that I had to put some washers to level it off.

However, if you bought it from unicycle.com, they will send you a replacement right away.

Keep on.

I recently received a 200mm club post from UDC that the top plate is visibly not square to the post. Crappy quality control on UDC’s part. I’ve not yet called UDC about it.