Lightweight ISIS cranks with some Q factor?

I am working on getting all of the parts together for my KH/Schlumpf 36er that I will be building up in about a month once my hub is returned from Switzerland. Does anyone know if there are lightweight ISIS cranks, similar to the no Q factor qu-ax isis cranks, that have a little bit of Q in them? I think the amount of Q on the KH moments is ideal for shifting and it provides a little bit of safety for not accidentally shifting. I find the moments a little bit too heavy though, and think that lighter cranks would be a huge improvement.

I guess I am asking two questions in this thread…

  1. Are there any lightweight ISIS cranks other than qu-ax (hopefully some with Q)?
  2. Is it wise to use lightweight cranks on a geared 36? Would the stress of a heavy 36" wheel in high gear put too much stress on light cranks?

Onza Tesiles, maybe?

Yeah, I was thinking about those as well, but I wonder if there are any other options. Does anyone know if the Q factor is the same on the Onza tensiles as the moments? UDC just says “medium Q factor” for them and not a measurement.

It seems like the difference in 137mm moments and 140mm onza tensiles is about 200g, which is significant. I will need to do some experimentation with crank length. I know that Chuck and Corbin seem to like 150mm cranks with their geared 36s, but 140s might be more my style.

I might just start out with my dual drilled 125/150s that I already have and then try out the 140mm onzas and see the speed difference.

I was able to find the answer to this question yesterday after talking with Tony Melton about how I hated using heavy KH Moments on my geared 36er. I thought that the only light ISIS cranks you could get were the Qu-Ax ones, which have no Q factor.

He pointed me to Nimbus ISIS cranks:

They are much lighter than KH Moments and look to have about the same Q factor based on a picture he sent me.

They do not look to be advertised on UDC US or UK, but I was able to secure a pair of 150s after calling UDC US.

This will save a significant amount of rotational weight on my geared 36er =]

My roommate just got a Nimbus muni for Christmas and it came with the Nimbus cranks, although UDC US only lists the qu-ax and KH cranks as possible options. Funny.

As far as I knew, the Qu-ax and the Nimbus ISIS cranks were exactly the same. I could be wrong though.

Here is a pic Tony sent me:

I tried putting the Nimbus ISIS cranks on my KH/Schlumpf 36er, but the cranks push too far on and hit the frame. I am not sure if this has to do with the shape of the cranks or the ISIS threads, but they will not fit on properly. I have heard others have problems with the lightweight qu-ax cranks as well.

It seems to me that either the KH/Schlumpf axle should be longer, or the ISIS threads on the qu-ax and nimbus isis cranks are not up to the same standard as the KH Moments.

I would only recommend using the KH Moments when using the KH/Schlumpf hub. I wish there were some lightweight cranks I could use on this hub…maybe in the future Kris or Florian will come up with something.

My experience with the QU-AX ISIS cranks is that the machining is not as precise as the KH Moments, or at least machined to a slightly different spec. The 2 pair of Nimbus ISIS cranks I have slide ‘loose’ on the ISIS hubs compared to the Moments. Not great tbh. Without spacers don’t know they would be usable.

There is also enough variation in KH Moment cranks to make them unusable on the Schlumpf hub, particularly if they are torqued up close to Florian’s spec. I had one Moment crank slide right up against the frame when torqued to less than Florian’s spec, the crank on the other side was ok. The Moments aren’t cheap, not fun to waste money like that.

I don’t think the solution is for the splines on the hub to be made longer, can’t see that solves much really, the cranks will just keep sliding further along.

The solution might be for the cranks to have ultra precise machining and for at least the ISIS part of the crank to be made of a much harder/more durable material. Alu is too soft imo for this use.

Alternatively having the Schlumpf support the use of spacers of some sort would help too.

Maybe a different way altogether of attaching cranks is required!

No doubt part of the bigger problem is the low volume runs of unicycle stuff but it seems to be too much of a lucky dip from an end user’s point of view.

wow why are the quax cranks like $90’s less than the onza tensils? Why are all the other cranks so cheap compared to the quax?

Nope, they’re completely different. I’d say the Qu-ax ones look a little stronger.


Not completely different, if you look on the back of the Nimbus cranks they are made by Qu-ax. (Though now Nimbus has some REAL ISIS cranks).

Here’s a pic of the nimbus cranks. (The image is way over-sharpened so that you can read the qu-ax)

Here is a picture of another kind of Nimbus ISIS cranks. These look like the ones that Tony sent you, James. They have some Q, but not much.

Yeah, those second ones (with q) are the ones I tried. I compared them to the KH Moments and the Q is very similar.

They probably work great on hubs with spacers, but they will not work on the KH/Schlumpf hub.

This is good info to know…thanks for giving it a try! I was going to buy a spare pair for our Africa trip…I guess I’ll have to fork out the dough for KH moments.

You are right: i do like 150s for the geared coker – but a lot of it has to do with the steep hills by my house. I probably couldn’t make it up my hill with anything less than that. I was considering experimenting with 125s again; I initially felt like it required too much push (and too much leg strength) in high gear. Unfortunately with my hub not working (again) I’ll have to wait a while to try it out.