Koxx bearing size?

Please help a helpless (maybe hopeless) Dad, for possibly a young kids best Christmas ever.

My son recently acquired a Koxx-One Tryall wheel. Apparently it has an odd size hub (For the bearings) A 22mm bearing does NOT fit. A quick measure appears that it is a 25mm ID.

So after HOURS of looking online, I can not seem to find a source for a 25x40(or42)X12 bearing.

Can anyone help me with as source to purchase bearings? Or at least the bearing number off of a K-1 hubbed-Uni?

Then… another question would be… does anyone know what width of spacer would be appropriate? And a possible source for those also.

Much appreciation to any help!

On a french website (which I didn’t know about until I googled), they have those:

Is that what you need?

They have very strange size 25x42x12mm.
We were looking for such bearing for our friend but found only these cart hub bearings…

The French site shows that as the bearing. But if you do a google on the numbers they list as a 9mm width. I had found that size earlier, but was not sure about the width if that would be an issue. Thanks for the help!

Most hubs use a 6mm spacer to the crank, one of the trials riders here might be able to give specifics.

I believe these bearings are going to become a lot more common soon as a 25mm axle allows the use of aluminium in heavier duty applications. Mad4one and QuAx have gone this way in two different designs and while it is sad to see proprietary standards re-emerging, it will hopefully lead to better hubs and likely a new standard.

I asked Romain, the man behind “CDK”, the biggest french unicycle shop, he says:
Those bearings are no longer available.
Best is to remove the little aluminium part on which the Koxx bearing are placed. Remove it, replace it with spacers to push the bearings away from the flanges. And then just use normal uni bearing directly onto the hub.

Hope it helps.

Take the old bearings off and the shim. Then replace the spacer with an equivalent length piece of tubing, it is either 10 or 12mm long. Then fit standard ISIS bearings. 22x42x12mm these are cheaper and better… also replaceable!


the monocirk bearings are the right ones.

&Roger is of cause also right;)