Crank Arms for Schlumpf (Square Taper)

This morning I decided to ride to work on my Schlumpf 36er. About a mile away from home, after stopping at a light, I shifted into high-gear. After several rotations, I found myself being intimate with the pavement. It became immediately apparent why. My Schlumpf crank arm was sitting on the pavment, have snapped clean off. Luckily I wasn’t going very fast when this happened.

Likely, I own too many unicycles, and I was still able to ride to work on my Nimbus 36.

So, I need new cranks. I’m thinking steel might be the way to go since they’re more likely to bend without breaking, and I fear what would have happened had I been going 20+mph downhill when it broke.

Does anybody have recommendations about strong cranks that work well with a Schlumpf? I’ll probably get two sets, 152s 140s.

I know that Joe Marshall and Spencer both had their 150mm Schlumpf cranks break as well. I am not sure what brand they are using now…it might be the ProWheel ones though.

quick reply as I’m on train at moment, but see;


Thanks! Any comments on the ProWheels now that you’ve been using them a while?

Ouch, hope you’re OK. Good excuse to try out those 140s we’ve been talking about. (And, mental note: extra square taper cranks in the spare parts bin for RTL).

I think the ProWheel cranks are what Jimbo is using; they’ve got a sort of annoying Q-factor.

I have a set of cheap 150mm steel cranks (straight) you can borrow/have. I can’t imagine ever wanting to put 150mm square taper cranks on anything I’m likely to own. I’ll be home after 8 tonight.

I also wonder if using cranks with no q-factor is ideal for a schlumpf. I would think you would want a little q-factor so you are not too close to the shifting button. I think the KH moments have about 10mm q and that seems to work great. I haven’t tried straight cranks on a schlumpf before though, so I am just speculating.

I’m using the Qu-Ax cranks, which I think are pretty much straight, and they’re fine on the Schlumpf.

I’m fine, just added a couple more scuffs to my collection.

The Q might be OK. I mainly don’t like the ProWheels for unicycles that have the extra-wide hub since it’s already pretty wide on its own. I have ProWheels on v54.

I just worry about them because they’re aluminum. Unfortunately, UDC does have much in stock in the way of high quality steel cranks, and by that I mean they have nothing.

My other option is the pricy Black Widows, which appear to have very little added Q, and they’re not available in 140mm.

I was debating switching to some light weight Qu-Ax ISIS cranks for use with the KH Schlumpf 29er. How do the light weight cranks compare to the Moments?

They’re light; in your hand, the difference is pretty dramatic. On the unicycle, I don’t think I notice the difference that much, but it probably makes spinning a little less wobbly. It took quite a bit of torque, and a 100km ride where one of the cranks kept coming loose all day, to get the Qu-Ax cranks tight enough to stay on, but since I bought the silly 6mm torque wrench bit and tightened them down, they’ve been fine.

Thanks for the info…if they didn’t make a significant difference I think I will stay with the dual drilled moments since I already have them torqued on there well and don’t want to go through all that hassle again.

Yeah. They’re great. They have got a bit more Q than the original Schlumpf ones, but that really doesn’t seem to be a problem. If anything, it is easier to shift now, although that could be because I went from 152mm to 127, and also changed my riding shoes at the same time.


Good that you like them. 127mm is definitely easier to shift, but I don’t think I want to go that short on a 36er!