Rim and hub replacement

I have an unused 29" frame lying about, and I was thinking about getting a 26" wheel and use that with the frame.
Is that a crazy idea? I can’t see why it wouldn’t work, except it might look a bit weird. The reason is that I already have the pedals, cranks and seat.

Also this:
I have a club 20", those have clotterless hubs, but I was thinkng about getting a isis hub to replace it, instead of replacing the entire cycle. That way it should be able to stand up to jumping and trails.
I wonder if the rim is good enough though.

What do you guys think? Is it worth it or should I just get a new cycle? I just hate having useless pieces laying around.

hi brian i recently built up a 29 frame with a 27.5 wheel and the gap up the top is not too bad, i did try a 26 wheel in the 29 frame and the gap just looked to much. if you are going to be building a wheel just build one that doesnt look to bad.

With the club its a lot of work to replace the hub to isis and cranks when you will still have the clubs rim. Clubs are good unicycles but if hoping and trials is your aim then i think it would be better to get better really.

Not crazy, and that is exactly what happens. Works (except for rim brakes, obviously), but the super big tire clearance looks slightly weird.

Depending on your weight, good quality square taper hubs like the one in your UDC club are generally fine for light hopping. (up and down curbs for example)
Usually the hub (or cranks) are indeed the weak spot, and the rims work fine for some mild trials.

I’m not sure what level you are at, and how heavy you are, but my general recommendation would be learning the very basics on the UDC club (up and down curbs), and if you then decide to get more into trials, get yourself a proper 19" trials unicycle (you will want the wider tires at that point anyway).

I don’t think it’s technical possible with the standard bearings. Aren’t the square taper ones 40 mm and the ISIS 42 mm? That would mean that your frame would probably not fit anymore except when you find 40 mm bearings for the ISIS hub🤔

Hi Becky, this should solve this problem. :wink:


Those spacers solve the opposite problem, @fetzenschorsch.
Isis Bearings are larger than square taper, those spacers are for putting square taper hubs into frames with 42mm bearing holders.

That being said, the UDC club has stamped steel bearing holder, so although they are technically designed for 40mm bearings, it’s usually possible to use 42mm bearings in them since the stamped steel parts leave enough space.


I think its not worth the trouble. I just want to use some of the extra cranks and stuff I have.
The club 20" will just have to last as long as it can.

Small wheel in larger frame works just fine if you aren’t using rim breaks and aren’t worried about the aesthetics. I’ve traveled with a single 36" frame with 36, 26, and 19" wheels to save space compared to three complete unicycles.

UDC has a very high quality square taper hub, the hub will likely outlast the rim on a club so no reason to upgrade that piece.

On the subject of 42mm bearings in 40mm bearing holders: it’s only really an issue with machined bearing holders which is only found on high end unicycles. Stamped holders work fine with either size.