Perhaps if there were enough demand, Florian could machine onto the crank-shaft a small “lip” that could accommodate the crank-shaft spacer for the Mountainuni disk brake/crank? So instead of the spacer pushing against the side of the hub bearing, it could push against a small lip of metal around the crank shaft that is just slightly outside the hub bearing? Seems like an easy enough modification to the crank-shaft???
I suspect strongly that if there is going to be a modification to the hub design to accomodate a disk brake, it will be a collaboration with Kris Holm, and not a quick fix to enable use of the MU system.
Well, I’m about to try that. Might need some more spacers between the disc and the crank spider, but it should work (?)
<crosses fingers and toes>
I don’t think that’s possible. The axle is in one piece. All components (clutch, bearings, sun-wheel, …) need to be mounted from the side, sliding them over the crank shaft to the middle. If there is a lip, you can no longer slide the bearings etc over the shaft.
Here is a picture of the axle with the clutch already mounted.
Or did I misunderstand you?
Ok I see. However, presumably couldn’t all the components be “slid” onto the shaft using one end of the shaft thus leaving the other side for such a lip?
Or how about instead of a lip, a shallow groove cut into the shaft and have a special spacer that perhaps comes in two halves that can be bolted together. The spacer would have a lip around the inner diameter that would fill into the groove cut in the shaft? Understand what I’m describing? Seems like there are a several possible ways this issue could be resolved. But I’m not an engineer or machinist so perhaps it isn’t so easy?
The thing is, ISIS accounts for this need by including a crank stop in the design, specifically to get the correct alignment of the crank. For bikes, this is to align the chainrings; in this design it would be to align with the disc brake.
Without a crank stop, the system is not ISIS-compliant, and in fact has this alignment problem specifically because it’s not ISIS-compliant.
There is a potential solution to this; see the ISIS spec, section 3.1.1, Figure 1. If we extended the cut-outs for the flutes, and had a pressed-on, removable crank stop which slid onto the flutes (after the bearing is already installed), we could have ISIS compatibility, a well-aligned crank, and fewer fiddly crank adjustments, because the system is designed to have force on the crank stop, not on the spline interface.
Ok, I see. But that means that there is no “ISIS” unicycle hub on the market that is really ISIS compliant. I havent’s seen any unicycle hub that has crank stops. 
Roger claims that the spacers used on the Nimbus line qualify, but I don’t really agree. In some ways it doesn’t really matter if we’re matching the spec, as long as the splines are the same, but if you care about the alignment of the system (as you have to if you’re running a disc brake), you really should have a crank stop.
Well, I took apart my much-sweated-over Schlumpf/MtnUni wheel. Looking at the SINZ/Schlumpf hub combo, the SINZ cranks actually contact and press against that little clip, so I think Florian would NOT approve of the SINZ cranks on his hub.
Furthermore, I see no way (aside from Tholub’s suggestion) to align the disc with the brake without at least a 2mm spacer.
I’ll be putting my MountainUni brake system on one of my non-Schlumpf wheels.
Steve,
That is disappointing. Does it matter which side you use? Can you flip the Schlumpf hub and get a fixed position with the Sinz crank on the other side?
Scott
I am disappointed in Florian’s response, at least we finally have one. We have chased that response for a while now and despite several users having no issues, his response is the same now as it was initially -no spacer can be used. Even if he didn’t answer us directly, we now know his official response.
The C-clip may become damaged and result in costly repair. Even if a few hardcore riders can show that there has not been any issues for more than a year of use in this manner, I understand Florian not wanting to warranty anything resulting from damage caused by a spacer. So, we can argue that it is compatible from the lack of repair issues or any issues so far, but for him to agree would mean that he has to guarantee it to an extent and possibly warranty any issues that may result.
There is a 2 degree taper in the ISIS system and without a spacer, cranks will creep inward until they strike the frame and need to be replaced. There is adjust ability in the MountainUni disc brake retrofit system, but I don’t know how much crank creep it will account for. The MountainUni system would certainly work without a spacer in Schlumpf hubs that are square taper, and so a blanket statement would rule that combo out as well so total incompatibility isn’t correct either.
The fact is that so far the Schlumpf/MountainUni combination has worked well and consistently, but we now know Florian isn’t down with backing up our innovation with warranty work and is understandably conservative in this regard. So we can’t claim outright compatibility, just that it works so far, so good -since we don’t intend to warranty any damage to the hub either.
Despite the current successes, it’s the way the cookie crumbles. It’s an at your own risk sort of thing, and that hub has a lot to risk and I understand the hesitation. Still, it works. Ultimately, the discretion is up to the end user.
Wish us luck on finding a potential solution to the spacer and crank creep with and without the MountainUni disc retrofit system on Schlumpf hubs. Respect to Florian and his advice, and good luck to all trying our innovation, and thank all of you for considering MountainUni.
That’s what I’ve been thinking, but such a spacer would need to be broached like cranks… not cheap.
It should work for both as Kris is working on something like the MountainUni system.
Yes. I didn’t want to mention that in the forum because I wasn’t sure how official it is, but Florian said it too. And I guess that it will be compatible with the Schlumpf hub.
Yes, that’s true. Production solutions will be coming but it will take some time for sure, probably many months and not likely in 2011. Florian’s comment can be interpreted as an “at your own risk” comment: bearing damage caused by pressure from a non-standard spacer won’t be warrantied. And it is true that excessive lateral pressure from a spacer will cause bearing damage. But as Jogi has mentioned, careful setup, a lower torque spec, and using loctite to prevent things from coming loose, has already enabled some riders to use a crank-mount disk setup for some time without damaging the hub. It’s up to the rider whether they feel comfortable taking responsibility for that setup.
Kris
Would we be better off with the older square-taper Schlumpf hub? Would that have a fixed position with respect to the crank and allow the use of a SINZ crank and disk rake?
Scott
Square Taper Schlumpf SINZ conbo
Scott, the Square Taper Sinz stock short as 115mm. The spacer would fix the rotor position, and 1mm CRB spacers to accomodate for any minimal creep over time. Great upgrade for a Square Taper Schlumpf to MU Disc & UCM & 6mm Crankstop Spacer.
oops. no need for a 6mm spacer on square taper
color me jealous! it would be nice to live close enough to drop my hub off (rather than ship it) should the need for repair arise (which I understand is not totally out of the norm)
music to my ears! my vacation (your holiday) starts in two weeks. tons of riding to be had. thanks to my trusty old Impulse (keeping her fully intact as a back-up / loaner for Ben King), none will be missed. fully expected to have my new KH36G in time and I might just yet but i’m certainly not getting my hopes up. i have been waiting patiently for Paul Revere (or Sara Palin) to cry “The Schlumpf’s are coming! The Schlumpf’s are coming!” Guess I’ll check back tomorrow. 
you and me both brother! i got the same estimate “weeks to a month” when i bought my hub (it’s in same batch as yours) on cinco de mayo 2011. BTW hope you don’t mind me cross threading (this is from the “New clear inner tube” thread) your reply. I did not want to threadjack over there and this thread (which I check religiously) could use a bump to get back on topic.
I don’t think I’ve heard of any failures with the new-style batch of hubs (larger cage, and bigger bearings than the original batch).
corbin