hubs/cranks and stuff

I’m not really considering any unicycle at the present but I thought I would just inquire a little about hubs, cranks and what goes with what.

Say I got a torker dx. If I wanted longer cranks, would I able to get some that fit that hub.
I know koxx hubs are different than “standard isis” but where does stuff like Kris Holm/Onza and qu-ax fit in.

If you’ve got any other info about hubs/cranks I’ll be glad to hear it. :smiley:

supposedly the quax cranks fit on a torker dx hub but it’s a little loose. Kris holm/onza both fit each other and they’re interchangable. The koxx-one cranks are smaller than standard isis which totally screws up other companies that were trying to make their cranks isis. So krisholm/onza is ther only real isis these days (correct me if I’m wrong)

your making it sound like the KH/Onza cranks are isis. They aren;t.

the Kh moment hubs and cranks are isis. So are the new Onza cranks.

the tubular steel kh/onza ones arent though.


OK:p You’re wrong. KH/Onza cranks are the old ones with 36 splines. The new ISIS KH cranks and hub are true ISIS, but lets not get into that again. The new Onza Tensile cranks are also ISIS, and so are the new Qu-ax aluminum cranks.

EDIT: Miles beat me to it.

ahh, so that’s what the new onza cranks are called.

toss me a link would you?

Koxx cranks are too big to fit on ISIS, they wobble.

Here they are on UDC UK, but there is no picture. I have never seen them, but heard they are pretty well designed.

Here is the whole uni, but they still have the picture of the onza with the KH/Onza hub and cranks.

koxx cranks are just as ISIS as kris holm cranks. it’s just that theyre made to different tolerences allowed by the ISIS standards. The koxx is much bigger than the KH, so they dont go together well.

All in all, if you get a koxx hub yyou use koxx cranks, if you get any other hub, you dont use koxx cranks basically.

But doesn’t that defeat the point of being ISIS?

ISIS set out a set of tolerences which they allow, both are within the tolerences. That’s just how it is.

its more than a little loose
my torker DX cranks fit on the Qu-ax hub, but they are messed up.

Koxx isis is not the same as other ISIS cranks/hubs
The Koxx cranks fit the other hubs, but the other cranks do not fit the Koxx hub

the KH moment cranks only fit on the KH moment hub.

Here’s a picture of the Onza tensile cranks from UDC NZ.

Did you actually measure this or do you just guess? The only measurement that I heard of was that the Koxx hub is slightly out of the specs.

Would be good to settle this once and for all. Unfortunately neither Koxx, KH or most unicycling resellers did anything to clarify the situation.

What would you like retailers to say? Roland has been very clear (ok in German) on the forum about the Koxx hub being outside tolerance.

I personally have not notified the forum about the tolerance discrepancies with the Koxx hub. What we did do was issue a gentle warning of none compatibility on our site. Being outside tolerance does not make it any weaker (or stronger), it just causes problems for retrofitting cranks.

It should not be the retailers who are having to do this work, but the manufacturer. Koxx as the manufacturer should be telling the retailers and customers, not the other way around. Remember when Kris had the manufacturing problem with the rim (not his fault but a manufacturers mistake)? He took the responsibility and arranged to get all the affected rims replaced. Koxx have refused to admit that they could be wrong. They were informed in September (6 months ago) of the discrepancies in their manufacture. Here is an extract of what they were told:

“I have then done a dimensional and physical check
on it. It seems to differ from the ISIS standard in 2 small ways. The
fluted length is too short, the ISIS standard is 16.00 +0.5/-0.0 the
KOXX hub measures 14.40mm. The second problem is that the flutes do not
seem to be deep enough. It is very difficult to measure this,
especially with the flutes being too short; but using a pair of good
vernier callipers they appear to be 0.2mm too shallow.”

Koxx’s response was that they were correct ISIS standard and KH, Onza and Quax are wrong. This response forced KH, Onza and Quax to do additional checks on their ISIS which were found to be within the ISIS tolerances.

This is a problem that I hope that Koxx can resolve because it makes it a lot harder for the retailers. The retailers have done everything possible to help this situation by feeding this information back quickly to them.


nope. you can swap out KH moment with qu_ax and onza isis cranks.

KOXX know exactly what the ISIS spec’s are, they’ve been using the exact ISIS interface spec’s on MTB bottom brackets and cranks for years…

When I asked them about the K1 ISIS, they said that the splines were intentionally made a bit fatter to increase the strength, since torsion applied to a unicycle spindle on impacts is far greater than torsion applied on a bicycle’s bottom bracket, given the fact that on a MTB the rear wheel hits first and the chainstay length provides a lever to absorb part of the energy… Which makes sense…

I don’t think they would have «made a mistake» with 3 different cranks and 2 different hubs models… If they want to use their own splined interface spec’s, they are free to do it… And personally, as long as it works well, and it does, I don’t see where the problem is…

However, I do admit that if a splined interface doesn’t match the ISIS spec’s perfectly, it shouldn’t be called ISIS, even if based on the basic 10 spline concept… for the details

Hello Roger,

thank you very much for your post, thats actually the kind of post I was hoping for. The measurement by Roland was the one I was referring to, but (as I understood it) it was just a quick check and not a confirmation without doubt. As we just saw in this thread it was up to now unclear if Koxx was ISIS or not.

Of course the retailers have no fault in this and suffer from the situation. However, if Koxx is outside the specification then it is not ISIS. ISIS is a protected name and using it for a non-ISIS component breaks the license agreement. Selling it knowingly under the name of ISIS is close to fraud (and this is also the responsibility of the retailers).
There have been multiple posts in this forum from confused customers on the matter of ISIS, so the incompability notice is not enough in my view. Why can’t you just call it “Koxx splined interface (similar to ISIS)”.

It’s true that only retrofitting is affected, but this is a big deal for some (like me). In my case it meant that I would have had to shell out more for cranks that I liked less (I wanted shorter ones). I felt really cheated and therefore sold my Koxx Devil (which was otherwise really good) to get a KH20 07 instead.

As I said I had hoped for a post like yours long ago. Why did it take that long to clarify the situation? The behavior of Koxx is in no way acceptable, and Koxx should feel the consequences. I tried to contact the ISIS consortium and inform them of the violation, but their email address did not work. Maybe a retailer would have better luck and other means of contacting them.

Thats interesting! So they either lied to you or in the response Roger spoke of?

I don’t buy the reason though, since the difference seems to be too small for any real effect. And if there was a good reason they could have informed the other manufacturers to achieve compatibility.

Thanks. :slight_smile:

Sorry this wins my favourite post of the day. A few points. Koxx are a trials bike company that have existed for less time than, which is considerably less time than Onza. They don’t make any MTB’s as far as I can tell.

Oh… and how can making the interface 1.6mm shorter make it stronger?

Oh and as for Koxx cranks fitting on everyone else’s hubs… sorry, this is a great comment as well. Of course it does, it is larger! it does not mean that it will give a reliable interface.


Last fall I built a Koxx 1/Truvativ Luftalarm/Large Marge wheelset (it can be seen in my avatar). Everything went together great. When statements came out about Koxx 1 not being true ISIS, I was interested in why. I did read Roland’s post on the German forum (translated by a friend and also remember it being stated as a rough measurement). I then measured my hub. My flute length was 16.0mm (within the spec) and the distance between flutes was roughly measured at 17.3mm (I don’t have a very accurate micrometer).

Since the Truvativ cranks fit on my Koxx 1 hub I assumed that it was within the ISIS specification. I then downloaded the ISIS spec and noticed that the tolerances in the spec make it possible for a set of ISIS cranks to not fit a ISIS hub. At this point I assumed that the incompatibility was due to the tolerances in the ISIS specification.

So it looks like I was lucky enough to have a true ISIS Koxx 1 hub and Roland saw a number of out of spec Koxx 1 hubs. It would be nice to have Roland confirm what he mentioned in the email to Koxx (hopefully in english :slight_smile: ).

I am interested in how widespread this problem is.

Was I just lucky to get an in spec Koxx 1 hub?
Were the out of spec hub’s that Roland measured because of quality issues or intentional?
How many other people have been able to fit (non-Koxx 1) ISIS cranks on a Koxx 1 hub?
How many people have not been able to fit ISIS cranks on a Koxx 1 hub?

It would be nice to get a “clear” answer from Koxx about this compatibility issue. Not just “we are within the ISIS specification”. It would be nice to see proof.