It seems that unicycle.com doesn’t include too much information in their product descriptions. In particular I want to know what the seat post diameter is for each frame and the width of the frames (from bearing holder to bearing holder).
the frames I’m most interested in are:
Yuni/N2
seatpost ???
KH24
seat post 27.2mm
Black Torker
seat post 25.4mm
Chrome Torker
seat post ???
United
seatpost ???
Other questions I have are:
What diameter is the GB4 universal seatpost?
How well do shims work?
Does it matter if the distance between the bearings and the bearing holders are different?
I am pretty sure all of those use the 22.2 mm seat post size. I just got a Yuni and it took my miyata seat post just fine and it is 22.2mm.
I have a 3" custom machined shim on my Muni that has always worked well. But the shims from Uni.com aren’t that long. As I recall they are only about 1.5 inches long. That was for a 22.2mm shimed to fit a 25.4 ID seat post tube.
All of my (GB4) posts are 7/8" or 22.2 mm in diameter. These will fit the Yuni, Chrome Torker, and United unicycles.
A 1" or 25.4 mm post will be available this summer and will be compatible with the new Velo saddles. The current GB4 posts are not compatible without removing some fabric from the inside of the saddle, or grinding some material off the seat plate.
I personally am not a fan of shims, but I know they do work.
FYI:
I just got my Summit 20. The seatpost on it is 27.2, but there is a shim in it. The frame is 29.4. I’m not sure if the KH uni’s are the same… Are they?
Shims can work just fine. But it does depend on the quality of the unicycle frame and the seatpost clamp. If the frame is prone to twisting seatposts without a shim it’s not likely to improve when adding a shim.
I just put a GB4 seatpost on my DM Ringmaster Advanced (thanks George). The DM takes a 25.0mm seatpost so I needed to use a shim to fit the 22.2mm GB4 seatpost. I got the needed shim from unicycle.com. It’s rock solid. The DM does have a double pinch bolt seatpost clamp which definitely helps.
My KH24 Pro and KH20 Pro both use a shim and the seatposts are rock solid. I’m using a Salsa Flip-Lock seatpost clamp which works very very well.
As long as the frame tightens up on the seatpost well and you’re using a good seatpost clamp and you’ve got a good quality shim then using a shim shouldn’t cause a problem. Beefy BMX seatpost clamps or Salsa seatpost clamps are a good thing.
The KH Pros definitely use a shim to get down to 27.2. I thought the
diameter was over 30mm but I’d believe 29.4 I guess. I’ve never measured.
Shims work ok, but best would be not to use them. The KH36 seat tube is
exactly 25.4 and Hunter makes his seat tubes exactly 26.8 (although he can
make you any shim you need).