I'd appreciate any feedback regarding my upcoming geared 36er build

Definitely most of the frames (including the mad4one) won’t fit without modification. A the M-series hubs were developed with Kris Holm, KH-Frames were always the only ones fitting on the hub out of the box. You can read more on this topic here:

Most frames (except KH) do not fit this measurements:

The generation M5 hubs may have some additional requirements but i guess, these measurement shown in the picture will remain the same.
What it takes to modify a QX-Frame is decribed in the linked thread. For the mad4one frame, there’s @muni_ben who comes to my mind first who has done the modification.

Regarding M4O frame: my #800 hub fits into my M4O frame without any modification. The only tricky point was to set up the inner disc brake - BrakeFast - as the caliper was too large too fit so I had to file the caliper base.


As @Maxence said, recent Mad4one frames fit Schlumpf hubs right out of the box. But yes, for older frames, the modification of shaving off the inner lip was necessary and Marco did that on request.


So basically the Oracle frame pairs with a 125mm hub and the Mad4One frame with a 100mm hub, so your choice of frame dictates your Schlumpf hub – or vice-versa…

I really like the look of the Mad4One frames and I like the double brake tab (so you can run two brakes if you really want – see Nathan’s video in this thread: Uni Santa Needs a Brake) , however I think I’d go with the Oracle one for an in-board brake just to get a slightly stronger wheel. I don’t think I would consider an outboard brake with the geared hub for the reason of transmitting all the braking torque through the gear train. Keep in mind that Ed Pratt went round the world on an 36" Oracle and didn’t have any issues with the frame (!) – they don’t come in so many nice colours though :wink:

With respect to cranks, as discussed, straight cranks on a 125mm hub would have about the same pedal spacing as KH Spirits on a 100mm hub – as also mentioned above though Spirits may have the advantage that they stop you hitting the shift button by mistake – you could run those no problem on a 125mm hub but the pedals would just be further apart. Likewise, hitting the shift button by mistake might not even be an issue for you with straight cranks (like VCX for example). I’ve never ridden a Schlumpf hub so I can’t comment, perhaps other with experience can say how much of an issue it is.


We could still hope the 100mm-double-tabbed Oracle frames will become available before mid-2022.

@toutestbon rides with straight cranks so he could help us on this question :slight_smile:

1 Like

Happy to have helped and it’s be fun reading about your piloting + photo fame and the chain of events that led up to this becoming known to you.

I’m always amazed by how so many unicyclists have such cool and interesting stories to share :star_struck:

I should say on the frame topic, it’s really good to hear that Mad4One newer frames, work out of the box.

I really like the look of them and that’s likely where I’d go with a 29er GUni.

For a 36er I would still lean to getting a Flansberrium frame. Heck maybe even something like this (now sold) one - Flansberrium 32" V-frame

In the thread on the above posting you can see @toutestbon amazing 36er V frame and basically it just goes to show what marvels the frames are from @jaco_flans - I don’t have one of his frames yet. But I am sure 2022 will be the year I order.

And you can be dead sure you’re getting one that’ll work with a schlumpf, customised to your needs and wishes.

I will be pleased to know more about the new torque reaction system Florian may have in store as with frames that aren’t KH I’ve always wondered how the little block thing would work. But it must just slot into any frame that doesn’t have the inside lip on the lower bearing mounts.

Like this:

1 Like

OK, I get it. From all the questions/comments I see you are assembling a unicycle to you own specifications. Not what I would do, just build your own from scratch. Jaco Flans is of the same mindset as I, if you want it right build it yourself.

On the frames, Nimbus has a 100mm dual disk tab Oracle style (gloss black aluminium) 36er frame now.

Roger informed me that UDC UK have them in stock but they haven’t yet had a chance to put them on the website. They should be available from next week.

I would presume that this is Schlumpf compatible out of the box and produced in part to ensure that Nimbus have a 36er frame compatible with current generation hubs. That’s just speculation though - we’ll just have to wait and see.


Some frames have the gap between frame and cap wider than this block, meaning that you will just lose it. I ended up cutting a little notch right in the middle of the upper lip and use just one of the two blocks.

1 Like

Wow! I’m amazed that it’s so popular! It’s fun to see how and where it’s being used. Thanks for your post and for sharing that cover photo.

Thanks! One of the things the hang gliding community has in common with the unicycling community is you get to meet lots of people who have cool and interesting stories to share. I’ve enjoyed hearing lots of them myself, so I am glad that it was fun for you to read about some of my adventures.

1 Like

Thanks again to everyone for all the replies and very helpful information.

Ok, so based on the latest information you’ve provided, apparently the Mad4one 36" is the only stock 36" frame that can be used with a Shlumpf hub (with disk brakes located on the inside of the frame) straight out of the box.

I’m not clear about whether the Nimbus Oracle 125mm will work right out of the-box with the 125mm version of Florian’s hub. If anyone has this information, please let us know. I’m also not certain if the soon-to-be-available Nimbus 100mm dual disk tab Oracle style 36er frame will work right out of the-box, so any definitive information about that would also be most appreciated.

The possibility of accidentally hitting the shift button on the cranks terrifies me. Such an occurrence could easily ruin my day (or much worse). If the spirit cranks significantly reduces the possibility of this occurring, that would be reason enough for me to go with them. I am quite keen to hear people’s thoughts on this subject. Is inadvertently hitting the shift button something that can easily occur with straight cranks? Are any Schlumpf riders who have accidentally hit the shift button following this thread? I am most interested in hearing about your experience and I would imagine others might be, too.

I have never ridden a Schlumph but I don’t like straight cranks because I hit the heel of my shoe on them all time. I have curved cranks similar to KH but actually Sun(a heck of a lot cheaper if you don’t need disc mounts) and I have never hit my heel on them unless it bounced off the pedal or something but that’s another problem in itself.

Thanks for your feedback, Unigoof. I’ve only ridden Cokers (which I think may have had a 125mm hub, but I’m not sure) with regular old, straight cotterless cranks and never had a problem. However, with a shift button on the cranks, even the remote possibility of inadvertently hitting that button concerns me, so I want to be sure to set up my geared 36er in a way that’s as safe for me as possible.

As to the initial question of the brake: I think the only real disadvantage other than the obvious complexity (but negligible compared to the Schlumpf hub) is that the braking power goes through the disc in high gear with an external disc. However, for on-road non steep downhill use I think this isn’t such an issue (For my 29+" Schlumpf that I ride for Downhill and in bike parks this is a concern and I would like to switch to an on-hub disc but that wasn’t available until just recently). As has been said, if this is an issue, I would look at the BrakeFast (although it is totally new and I have only seen the photos and diagrams from Maksym). Technically, yes, having a internal disc makes the wheel weaker, as then the wheel is asymmetrical (ok, you also have to buy 2 separate spoke lengths). But in practice this is not a problem and if it were a big problem, than basically all modern rear bicycle wheels are weak as they as really asymmetrical with a cassette. Unless you’re going for an ultra-light build with crazy custom stuff like super thin spokes or reduced spoke count, then I don’t think it should matter. I have had no problems with my internal disc on my ungeared Oracle 36.

So yes, definitely get a brake. I can’t imagine going fast in high gear without a brake! Similarly I don’t like riding my ungeared 36 fast with short cranks (110/100mm) without a brake. Of course braking-through-the-hub in high gear causes extra stress and wear, but I think for on-road use it is not such a problem.

Concerning ghost/accidental/inadvertent shifting: I have KH Spirit cranks and I have had a few ghost shifts, but I would say it is mostly an issue of practice and the right shoes. I personally have straight cranks (VCX multihole) on my fixed 36" with 125mm spacing (Nimbus Oracle). And I have Spirit cranks on my 29+ with and without Schlumpf. I find the right shoes to be key to shifting the Schlumpf: with my clunky FiveTens I can shift pretty well but when riding in normal sneakers I sometimes can’t shift on the go and have to stop or totally slow down to shift (I’m sure if I practiced then it would improve).
I think it also depends on your crank length and shoe size. With 127mm/117mm cranks and my US size 11/EU 45 shoes my foot and parts of the shoe run near the shifter but with longer 150mm cranks my foot is further away so basically can’t shift unless I actively reposition my foot.

Q-Factor: Without having lots and lots of long-distance road experience and not being a track racer, I would say the wider Q-factor is only an issue if you want to spin really high RPMs, as the width gives a little more side-to-side motion and/or you have to work a little more against the side-to-side as the Q-factor increases so a smooth high-speed spin is easier with a low Q-factor (but with the Schlumpf high RPMs is exactly what you don’t have to do). Of course this may differ for someone shorter (I’m 6’1"/185cm tall). So I think for a Schlumpf it is a non-issue and/or just personal preference.

As to the wheel stability of in-board or out-board, as a downhill rider who really stresses my wheels, I think for on-road use any of these should be fine (not sure if this changes if you consider a really light carbon rim although generally carbon also has great lateral stability). I have had almost no wheel/hub problems with any of my inboard or outboard discs… actually that’s not totally true as I my first 125mm hub on my Oracle 36 wore out as the spoke eyelets pulled out of the hub, but I think it was more from basically never truing my wheel for a long time after I banged the rim a few times and then tighting the spokes up too much rather than the wheel/hub design).

As to the frame choice (I didn’t even know there was a 125mm Schlumpf hub now available): I think they are all good frames and you just need to make sure they fit the Schlumpf. The Mad4One frames are nice and the double-tab is a plus if you decide to change anything later and I would trust Marco if he says it takes a Schlumpf hub. And if you stick with the 100mm hub spacing then you can definitely use the KH Spirit cranks if you want to push your ankle out from the shifter without getting a massive total Q-factor.

Wait I just realized I maybe missed something: is there a new Schlumfp hub with a disc mount? Or are you already planning with the BrakeFast or similar mod? Because as far as I know there is no out-of-the-box capability to mount the disc directly on the Schlumpf hub. An external disc with the disc mounted on KH Spirit cranks works (but braking force goes through the hub), which is what I have on my 29 Schlumpf on a KH frame.

Oh, just a last comment and of course crank length is such a personal thing, but if you were previously riding without a brake, then just be aware that the world changes with a brake. While I think a 36 Schlumpf with 150mm cranks is fine for on-road in high gear 150 is quite long for low gear, and you could consider a bit shorter (my ungeared 36 I run mostly with 125mm cranks as I ride lots of off-road but would go down if I only rode road, although the 100s are really short so don’t like so much in the city where lots of other people are around). For my 29+ Schlumpf which I mostly use off-road I switched from 117/136mm to 127/150mm as the 136mm in high gear was a little too much for me off-road right now. But on the road the 117 in high gear are great! Which translates into effective 138mm for a 36 (my 29+ has an effective diameter of 30.5").

There will be in a few months! Have a look at this thread: ⚙ Schlumpf hubs produced again.

I think it’s worse on road, as you’re likely to be going faster and braking harder in gear. The high stress/impact stuff off-road is far more likely to be in 1:1

1 Like

This hasn’t proven to be an issue for me. I have 125mm cranks with high Q factor on a 29” and have spun up to about 248 rpm. I actually have an easier time spinning fast on high q cranks because I don’t have the fear of hitting my heel on the crank and getting launched into next week.

Thanks for your very thorough and informative response. I learned a lot from it and now thanks to you and the other forum members who replied to my post, I have figured out all the components I want to utilize for my upcoming geared 36er build.

Now I just need to figure out how in the dickens I’m going to get the wheel for my geared 36er built! I don’t have the skills to do it myself or the time to learn how, so I’m hoping I will be able to find a good bike shop (or unicycle wheel building guru) who I can hire to do an excellent job of building the wheel for me. Does anyone know any such bike shop or guru in or near NYC who would be up for the job? If there isn’t anyone in or near my vicinity, I will resort to shipping the wheel components somewhere else, so suggestions for a company or individual anywhere in the continental USA would be most appreciated. Thanks!

If you buy your spokes, rim, and hub from UDC they will build your wheel for about $60 I think. Not sure if Schlumphs are gonna be sold through UDC but it’s probably a safe bet.