Upgrading a 26" to a 29" wheel

When I built my triangle frame uni, I left 2" of clearance between the seat post and rear brace tubes. I currently have a Duro 26" X 3" tire which has an outside diameter of ~28". My shaft collars are designed for a KH Moment hub.

The questions is: can I build up a 29" XC or cruising wheel, that will fit inside my frame? It would be really cool just to swap out wheel assemblies and have a 29er with shorter cranks. What is the outside diameter of a KH 29" tire.


I just mesured my KH29 wheel with BA 2.35 tyre and it has an outside diameter is about 29 1/2 inches. But with my kenda “the klaw” tyre it would probably be a half inch smaller.

Ok, cool.
So now I’m thinking, if the difference between my current set-up and an entire wheel build is about 1 1/2" of tire diameter. I have 165mm cranks. Wouldn’t it be more economical just to put shorter cranks on to arrive at the same ratio of crank length to tire circumference as a 29er?

The KH 29" has stock cranks at 125/150mm. Any mathematicians out there?


Shorter cranks may be easier to spin faster, but you still have to spin more times on a 26" wheel than you would on a 29" wheel to travel a given distance.

When you say you want an “XC or cruising wheel,” I’m assuming you want to ride longer distances on the road and maybe light trails. If that’s the case, I would work my way down from 125mm cranks, unless you’re already comfortable with shorter. A 29er with 125s was my first “distance” uni. The “short” cranks were tricky at first, but anything longer will feel clunky on the road once you get used to it.

If you want a wheel for cruising on the street I would sugest building up the 29er wheel. you will notice a huge difrence between that and a 26X3" wheel. I have a muni with the Gazz 26X3 and put short cranks on it, didnt like the combination much then built up a road wheel with a 27 X 1 1/4" tire (about 29.5" OD) with the short cranks. the difrence was phenominal.

The skinny light tire had way less rolling resistance and was much more “snappy”

unfourtunately this is also the wheel that I was using when I destroyed my shoulder last year so doo be carefull of going too short with your cranks.

good luck


I have a uni set up this way: a Gazz 26x3" with 170mm cranks is one wheelset, and a Big Apple 29er with 125mm cranks is the other. A Yuni 29er frame fits both tires. The outside diameter of the two setups is quite similar, but the wheels ride totally differently; you can’t just look at crank length compared to wheel diameter to assess what kind of ride you’ll get.

I call it Frankenstein, because it’s a little weird and thrown together from the remnants of other unis. It’s not perfectly ideal, because the beefy frame is wider and more knee-knocking than would be best for 29er mode, but it is nice to be able to loan out a uni for either road rides or MUni rides, depending on what’s needed at the moment.

If you do this, you will want to do something about the bearing holders. Total best would be to get Jim Roberts to make you a set of his quick-release bearings so you can swap back and forth quickly. At the very least, you should use acorn nuts and lock rings rather than lock nuts, so you can hand tighten and loosen most of the way.