Opinions on UDC chomoly hub/square tapers

Hi folks, I just ordered a UDC 48 hole chromoly hub.

I am looking for opinions about this hub, as well as any knowledge about the variety of taper used for the crankarm interface.

In the bicycle world, square taper bottom brackets are usually JIS (e.g. Sugino) or ISO standard (post-1994 Campagnolo).

What taper is used on the UDC hub? I ask because I may try to save a bit by using some identical left-side bicycle crankarms I have lying around unused. Is there any reason not to use left-side bicycle crankarms assuming they are for the correct taper?

I am hoping (assuming?) this UDC chromoly hub will fit in my Rick Hunter 29"/700c unicycle. I know the Hunter has a 40mm bearing spec and was designed for the Profile hub. I can’t afford the profile hub right now, and I have a new, unused Mavic T519 48 hole 700c rim that I can use for my wheel. I ordered a Schwalbe Big Apple tire to use for my street/commuting purpose.

The UDC site says that the UDC 48 hole chomoly hub has 17 x 40-mm double-seal bearings. Think these will fit my Hunter?

Bicycle Crankarms tend to be on the longside (especially if you’re riding on the road with a 29"). And you have to cut down the spider/chainring attachments on the right side.

If you use two left hand crank arms on a unicycle you will find the lefthand crankarm you put on the righthand side is at risk of coming loose while riding and the thread will strip out if you carry on riding.

This is same thing that happens when newbies put the wheel in the wrong way round in their unicycle frame and wonder why the pedals fall out while riding.

You can quite easily buy square taper cranks for unicycles (they are also known as cotterless) cheap ones only cost $12

If you have a left crank on the right side you should add an insert to reverse the thread so you can use a right side petal. The insert itself isn’t that expensive but the tool needed to put it in apparently is.

The UDC hub is very solid, I have wrecked a few pairs of cranks on a couple unicycles with the 36-hole version of this hub and the hubs themselves are still in perfect condition.

Are you planning on using your Hunter for road riding or MUni? Bike cranks are a good length for MUni but are really quite long for road riding.

I have no idea what taper the hub has but I did put some cranks on one from an old (1970/80s) road bike once and it worked fine.

Road riding on Hunter

I do intend to ride the Hunter on the streets, and to commute to work on it.

I found some Sugino cranks online that are reasonably priced and have both right and left side versions available, addressing the threading issue:

I am thinking to go with the 152mm cranks for street use, longer for MUNI rides.

I am still rather perplexed with bearing sizes. I know the Hunter takes 40mm bearings, yet I see a variety of widths for 40mm bearings. I am hoping (with a longer-term view) to eventually put a Schlumpf GUNI hub in it, and it looks like the 2008 model will not require a torque arm and the square taper version takes a 40mm bearing specification.

Is anyone out there using a UDC hub on a Hunter?

Thanks for all the help, folks!

Expect cotterless cranks to break frequently if you ride anything other than smooth trails.

If you intend to go off road on a geared hub, I’d get the KH when it comes out. If you break the square taper on the cotterless version that would be very expensive to replace.

I have sugino 140’s on my udc hubbed 36

They seem to fit fine. I like them, they seem light and well crafted, perhaps they are forged, I don’t know. They have about 10 mm q a side, which is ok by me, but maybe not for everyone.

All of the 40 mm uni bearings I have seen are 12 mm wide. I don’t know about the Hunter though.

Bearing spacing

Is measured from center of bearing to center of bearing. So measure from center of bearing holder to center of bearing holder on the legs of your Hunter. That will tell you what size to shop for. Most of my uni’s are 100 mm. Some of the udc hubs are wider then that I think, at least for the 36.

I think any 40 mm bearing hub will fit in your hunter, as long as the bearing spacing is correct.

I’ve had no experience riding cotterless cranks off road myself, I was just repeating what I’ve read on here DOSENS of times.

According to this thread, if you don’t do any drops, cotterless hub/cranks are fine as long as you get strong ones.

152s on a 29er are pretty long for street riding. I use the 150 hole on my KH29 for more technical muni, and the 125 hole for less technical trails. On the road, 125s are as long as you’d want; 112s or even 102s might be preferable. I don’t really ride on the road much, so can’t comment a lot on that aspect, but others on the fora generally find that 125s are a reasonable length for most people on the road when riding a 36er, so shorter may be called for in your particular application.