Schlumpf non-ISIS bearing frame fitment options

(Starting a new thread as this seemed more specific than resurrecting the general discussion)

I’m already in the early stages of possibly acquiring a 2nd Schlumpf for a 36”.

It is however a square taper crank mount version. Pre KH, but after the torque arm version - so is using the knurling.

From tons of searching via the interwebs and this forum I believe that this version is still using the 40mm bearings even though it switched to using the knurling (but I am not absolutely sure… anyone know?)

If 40mm am I able to use shims with this to install in a KH frame?

Alternatively I have a spare NightRider Frame (non-magura) which I presume is the later model with machined bearing holders.

I can see that the square taper hub and NightRider frame do appear a more common combo, but the frame has to be cold set to be narrower - and then the bearing holders would I presume still needs to be modified or shimmed to grip the knurling on what I presume are the smaller 40mm bearings.

I have posted a similar question on the Facebook group for Geared Unicycles - but I wanted to ask here in case anyone has had similar puzzlements.

I’m clear on the torque arm version. And know how the KH ISIS muni hub has developed…

But try as I might I can’t find definitive specs for what appears the second iteration of the “first gen” square taper Street Schlumpf hub that looks in photos almost like my M0200 series hub barring the square taper crank mount.

I don’t think I’ll ever ride this 36” set up in any realm of hard core so I am less concerned about crank strength- but the approach to getting this securely set up into a frame seems like the complex / hard to gage step that I would welcome any tips or help on :pray:

Thanks in advance!

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Hi @mindbalance,

That is indeed an interesting predicament worth its own thread. Disclaimer: I only got some M8xx limited experience with schlumpfs but wanted to give my 2 cents:

  • ideally a 40mm bearings frame (UDC square taper still sold today?) would be the simplest option as the bearings will be well supported. And if the bearing cups are too hard for the knuckled surface, you can use some aluminium tape as shared in the main thread to increase the friction
  • if you are forced to use a 42mm bearings frame, the shims will provide an added challenge: 1) you will have to ensure the knuckled surface grips the inside of the shim and 2) you will have to find a way to stabilize the outside of the shim in the holder. For the inside contact, either soft material for the shim or friction tape may do the trick. For the outside, I am afraid that you may have to resort to some sort of tab welded to the shim to prevent rotation. You can make a small tab like the M8xx and grind the slot in the cup&frame junction or you might be able to weld a flat piece of metal that would fit in between the cup and frame and be clamped (just make sure the weld is strong enough as le leverage arm will be a lot bigger that the tiny stub on the M8xx)

I hope that whatever solution you come us with, it will work for you and illustrate this thread with pics :wink:

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Thanks so much @Siddhartha_Valmont for your reply.

You’ve hit the nail on the head when it comes to my challenge- which I have yet to even commit to 100% as I am only 99% certain I’ll go for this square taper early steet Schlumpf hub. But tempted I am. To have a geared 36er would be nice and as I know my riding is anything but hard core the non-ISIS cranks don’t worry me in terms of durability.

I’m thinking along the line of using shins as thanks to another Felix on Facebook Geared Unicycling , I was reassured a bit that this is possible.

But as all the torque with the version of hub we’re talking about goes via the knurling (no arm on this one, and no more advanced tab/notch like the 800s) - the shims as you say would need to be fixed into the frame.

I have two frame options I’m mulling over.

  1. My KH36er
  2. Nimbus NightRider (no magura mounts, machined bearing holders)

The KH is probably the way I’ll go as it is already at 100mm for the hub width and saves trying to cold set the NightRider (although I may cold set it so I can use it with my non-geared 36” “donor” wheel from the KH36!).

For the shims. Probably use theses:

But I’m thinking of cutting them into two half circles and then investigating the use of either my own attempt at knurling them or using a super strong metal glue. I’m no engineer but I presume they’d only need to be as strong as the knurling interface that would be basically fixing the hub’s bearings into the frame - so I am kind of hopeful that sticking them into the KH frame would work - and maybe find a way to notch each end of the half circles so they are less inclined to spin if the glue fails.

If I did go with the NightRider frame and first cold set it. I’d still have to shim the mounts and I’d be left with no magura mounts to run a break.

To put my donor KH36 wheel back into service, I may look at using that frame and dBrake mount to get it working again as a fixed 36”. Always liked the frame design and I’m again not a super aggressive rider - so any flex isn’t going to bother me.

I may even go as far as to build a new 36” disc hub wheel for the frame at 125mm so I don’t have to cold set it and it works as nature —- or Nimbus intended.

But that’s off topic.

I hope my shim idea will work but before I decide I’ll probably run it by the folks at UDC UK to be sure I’m not completely wrong or missing a better solution.

It’s all getting a bit complicated in my head right now as the Schlumpf hub is an odd model in that it isn’t the newer ISIS KH model but it also isn’t the one with the torque arm.

On my 200 series KH Schlumpf I’m already pretty happy with how the knurling works as a torque reaction limiter, but I do get a bit more twitchy around shims that might slip - or worst case over compress the 40mm hub bearings.

But all this will be worth the mental puzzling and head scratching once there’s a KH36 with this gear and maguras up and running :heart_eyes:

If you have any thoughts on my plan / ideas that might help, please do say.

I’ll keep this thread posted on what I end up doing!

Hi, sounds like you you have some knowledge or access to machine tools to knurl. So why not drill and tap a threaded hole on the holder attached to the frame to each side of the frame pointing to the center of the axle and install pointy set screws to dig into the shim or even put a hole thru the shim so the screw contacts the knurl directly to give it some bite?


That’s a good idea.

I may sound like I know what I’m doing. I have no tools or knurling experience.

The hub is knurled. But the shims would have to be roughened up and then glued / locktited (?)…

It’s going to be a bit faffy but sadly there are zero options at the moment on a frame with 40mm bearing holders. And as I don’t think I’m aiming to ride the GUni hard, I would home the wheel will hold.

Your idea is good and it did occur to me to see if I could find someone able to drill or notch the shim in place.

My worry here would be that anything pointy or bolted in place “might” work its way into the hub’s actual bearing if the shim metal is too soft or deforms. It may be enough to just find some aluminium tape of a high grade and build up very precisely and evenly layers to 2.1mm thinkness as this would be sticky and deform to mesh with the hubs bearings and the knurled side.

As you can see. I like giving myself a project and a half. I haven’t even started on planning out the rebuild of my fixed 36” which I want to do when doing this GUni build / wheel swap-over.

Wish me luck and thanks for the suggestion :pray:

Sounds like you have your hands full to have a busy winter :wink:

As you mentioned UDC UK, I was surprised that they do not list the frame used by this uni:

As the hub is coterless and mentioned compatible with most coterless unis, it must be 40mm bearings with 100mm spacing. You may need to give them a call to ask nicely if they can sell just this frame (or have an equivalent one sleeping in the warehouse).

And if you get cold feet or you analysis becomes too much of a headache, I am sure another rider will be glad to carry on the torch (I never thought we could find second hand road schlumpf but now you got me jealous :stuck_out_tongue: ).

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Mindbalance, The best of luck with your project. Hey Sidd, I have an old original schlumf 29er road uni you might like. I have stopped using it the last couple years as it has become too fast for me to bale at speed and survive ( no rash ).

00102, disc on hub mod. torque arm model

post a picture of your unis 178 aug. 14

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It would be amazing if the Nimbus trainer style frames for 36ers stayed at 100mm like their smaller sizes. But while it has 40mm bearing housings it is at 125mm width.

Yep a bit annoying. Can get one part of this right and one eludes me. Fingers crossed the KH + Shim route works.