Onza brake mounts

Having recently bought an '05 onza trials, I noticed the other day that the brake mounts don’t appear to be in line with the rim edge, i presumed that it was designed to be used with Magura HS33s but i think if i fitted a pair they would only work on the tyre, which is no good. The lower of the two threaded bolt holes is about level with the rim, as far as i can remember the cylinder is equally placed between the two mounting holes on one of those brake cylinders, so it would miss by quite some way. Can anyone shed any light on this? Does it require different brakes, different mounting hardware, or have I somehow got a duff frame?

Yeah it’s pretty much centered.

coker brake mount1 small.jpg

Another picture.

Cheers pdc, this is what mine looks like, anyone got any ideas?


YIKES! I dont think there is a fix for that other than cutting off brazing on a new one and re powdercoating. Can you return/exchange it to the vendor?

Is that a 20" or a 24"?

It’s a 20", I think it’s going back to UDC, i just wanted to check on here first to make sure i wasn’t being stupid. If mine’s been incorrectly made then presumably there’s a whole batch of them out there, check your Onzas people!

Wow dave, I didn’t even notice! Thats a very long way off, its too far up for even a 20" rim, so I can only assume that they used the 24" measurements or the 24" jig to locate the mounts, without realising that the frame was a 20". Return & replace the frame, Roger’ll sort it out. Before you send it, make a measurement of bearing holder to mount distance, and we’ll compare it to my onza 24" at christmas.


Why do you want HS22’s on a trials unicycle?

I’ll bet they measured the brake location for a 20" BMX wheel rather than the 19" trials wheel. A 19" trials rim is slightly smaller than a 20" BMX rim and that distance appears to be about the same as your brake mounts are off-center.

The mounts arent measured for a 24" frame, right now i am riding my trials with a 05 24"KH frame and the mounts are higher than that, the bottom one is even with the tire.

Roger’s reply to my email:

“The brake mounts on the Onza are a mystery for several reasons.
Firstly, As you can see they are not in the right place for the 19” rim,
they appear to be designed to fit a 20" rim if fitted. Secondly, they
were not specified with them at all because brakes are not used on
trials unicycles…"

Now i beg to differ on the subject of trials brakes, but as the advert on UDC’s site does not imply in anyway that the Onza has brakes (either in the description or the photo) then I suppose I can’t complain about the brakes that I have but which can’t work.

For trials brake uses search, there was a thread a a few weeks ago.