Write up and thoughts on Schlumpf drive

I recently had a go on Tony Melton’s schlumpf 29er while I was in New Zealand and I thought I would post my thoughts about the schlumpf.

I first tried Joe Marshall’s schlumpf earlier on the SINZ unitour and he had a schlumpf 29er with 150mm cranks. I found it difficult at first to get the action down of hitting the button to shift, but when it did engage it wasn’t too difficult to keep on riding. I personally was not as big of a fan of the 150mm cranks, but it makes perfect sense to have 150mm cranks if you are going to be doing long distance AND some light muni trails as Joe does, and this is a great use of the uni. Joe’s frame was custom made by Roger Davies and was quite nice in that it didnt flex or hit your legs.

I tried Tony’s schlumpf at a later date and with the 125mm cranks I was able to shift SO much easier. I was actually able to shift halfway up a hill very smooth, and then I was able to shift on every pedal stroke while riding on flat. Shifting with 125mm cranks is extremely easy and smooth. The only downside of it which others have posted already is that the new Schlumpf frame is quite annoying. You need to loosen 8 things to change the seat height, and the crown of the frame hits the back of your legs on every pedal stroke…it is very irritating.

Shifting with smaller cranks (125) is easy because you simply need to turn your foot in and rub it along the shifter button to shift. Shifting with 150mm cranks will probably take a little more practice, but I do not find it extremely difficult like others have stated. Shifting halfway up a hill is very practical and there is no need to dismount before shifting.

One last thought is that the low gear feels very low with a 29er…even with 125mm cranks. After climbing mountain passes in New Zealand with my Coker with 125mm cranks and 150mm cranks, anything less feels slow and annoying. The high gear is quite fun though.

I think that the ultimate geared unicycle would be a 36" uni with the following:
-a nice frame
-125mm cranks
-schlumpf drive with a smaller gear ratio…1:1.25 or so…so it is a 45" equivalent

This would allow the rider to keep using relatively small cranks in high gear, which is one of the problems with using a 36" schlumpf right now…you need to use long cranks. In high gear it would act similar to the schlumpf 29" in high gear…but it would be smoother, and in low gear it would simply be a coker with 125mm cranks…which allows you to ride up almost anything you will encounter on the road.

That is my 2 cents.

Any thoughts on my idea for the “ultimate” geared unicycle?

I think even with 125s on the 29er, the low gear being super-low isn’t too much of a problem. Usually at the point you need to use it, it’s really got super steep, and you’d be better off spinning fast in low gear than cranking away slowly on a coker, or it’d just be unrideable (eg. Arthurs Pass).

If you spin well, it’s perfectly possible to hit 13mph on the 125mm low gear (if you spin like Ken, even higher), I think the overlap between the two gears is already enough.

If I ever afford a KH/Schlumpf for muni / mixed riding, I’ll probably put 125mm cranks on the current schlumpf and keep that for road.

Overall though, the only major advantage Schlumpf gives you on the road is the emergency low gear, the coker is fine for 99% of road riding, the great things about the Schlumpf truly are use for on & off road combinations of riding, and convenience for traveling.


Right, but as for most of the riding you won’t need a 29er with 125s. Sure it would have been nice on Arthurs Pass, but for most of the tour I think that if I had the gear ratio on a coker that I described I would be very happy. When I needed to climb most mountain passes…or some of the rolling hills I would have switched to low gear (36" with 125mm cranks = sufficient for almost all terrain we rode), and when I would be riding flatland or small rolling hills I would have switched to high gear (45" equivalent or so with 125s would be fast and smooth). I think that the problem with a 36" schlumpf is that the gear ratio is so high that you need long cranks and isnt as practical as a lower gear would be for most of the riding you would encounter.

I agree that right now the schlumpf is great for on/off road combos and shipping, but with a few changes in the gearing (if it is even possible) Schlumpf could make the perfect hub for a long distance 36" unicycle.

What about a Schlumpf 20"?

The other 1% :smiley: :

Right now any geared standard (non-giraffe) unicycle is ultimate. They’re cool like that.

The configuration of the ultimate geared uni is going to vary from person to person. Depends on how they like to ride. Some people spin really well and like to pedal at 130+ rpm with shorter cranks. Other people like to pedal slower and may prefer longer cranks for more power and ease of staying seated while climbing. The nice thing about gearing is that the unicycle can be tailored to be ultimate no matter which end of the spectrum you’re on.

Yes, indeed shifting gears on a Schlumpf is remarkably easy and can be picked up in minutes. siafirede was shifting every pedal stroke after about 15 minutes practise.
I should point out that my Schlumpf has a 36" frame, but a 29" wheel. I’m going to shorten the fork legs soon, which will fix the problem of leg strike on the crown.

I agree that the 29" schlumpf in low gear seems waaay too low, so I’d like to see a schlumpf hub with a low gear of, say, 1.2:1 and leave the high gear as it is. That way in low gear its like you’re riding a Coker (which can be ridden up darn near any paved road in the world) and you get the benefits of having short cranks and easier and cheaper transport/shipping. In my opinion with would be the ultimate touring and racing unicycle.

Florian Schlumpf recommends to shift gears by kicking the button (in the direction of its movement) rather than rubbing it. The reason is that the shifter axis can bend quite easily and then may get stuck. I’ve seen this occurring during Unicon XIII.

Schlumpf sells (or maybe sold) a kind of rub plate to be attached to the cranks and go over the shift button. But Schlumpf says that this makes shifting TOO easy, accidental shifting could happen too easily.

Klaas Bil

I would realy love to try the 20" Schlumpf!! i’ve got the 29" and have had for about 2 years now and found it amazes me every time i get on it! I do agree the the frame is a bit chunky but it does look funky(well, different anyway), and the old one didn’t hit your legs so much. But one thing i’ve been wondering is with the 20" could you get up the other side of a half pipe? it’s easy to dropin, but getting up the other side with a normal 20" is almost impossible. if anyone has tried this or has a 20" Schlumpf and could tell me what they think that would be great!



Florian Schlumpf has a 20" Schlumpf that he built up for his Daugthers to ride. You might want to ask him. I only had a quick ride on it, and it is reasonably fast.