Schlumpf hubs: general discussion

Thanks Bert

I think part of the problem has been I have been swapping cranks a lot and that constant working of the hex probably caused some fatigue… I did find the bolts loosen quite a bit…I put this down to 2 things… 1. every time you fall and the uni bouces on the road there is a high frequency vibration that will go through the whole uni causing everything to loosen…2. the contact area of the bolt head against the moment crank is tiny, I cant see any reason why it has to be so small??

[QUOTE=UPD in Utah;1470864]
Hey Alan,

Sorry to hear about your stripped bolt. I understand Florian & Kris are still trying to solve this one, but meanwhile, will be sending out a “cranksetter” bolt with the new hubs. (Correct me if I’m wrong, Kris.)

If you have yet to here of the concept of a cranksetter, you can get a description here: Schlumpf hub setup discussion thread

I understand from Hugo & others that you really don’t need to drill out the center of the M12 bolt, since there is sufficient clearance, but it’s not hard to do and it allows you to visually check whether the shifter rod in “in” or “out.” The main advantage is that the “standard” M12 has an 8mm hex slot, which will take the torque required to properly set/seat the crank (i.e., 40-50 Nm, or 35 ft/lbs; see page 4 of the current KH/Schlumpf manual at I used quotation marks on “standard” since it turns out that M12 bolts come in different lengths (but always the same 12mm width, with an 8mm hex slot in

Hi Burt
Will the bolt from another KH uni work as a crank setter?

New Schlumpf Hub


A large box arrived from Mr. Silva a few days ago. I opened it to find a nice Schlumpf hub built into a 36” wheel. I gathered the parts I had lying around my garage and assembled a 36” KH guni. It all went together well with a few torque wrenches and some care. (I am still not sure how far the buttons should protrude. Right now I can slip a paper card behind them when they are extended. I might take them in 1 mm.) I put the gold button on the right and am using 125/150 mm cranks with the pedals in the 150 holes.

I assembled the buttons with a Wiha economy torque wrench, which worked very well. It is a 2 Nm fixed torque wrench with a 2 mm hex blade for about $50 which makes the process very simple. I would recommend it:

The first ride was uneventful. I set it to low gear, mounted and rode around the block without any problem. I do not usually ride 150 cranks, and the tire is a bit heavier at the hub and lighter at the rim than my other 36” so the feel was slightly off, but I was easy to ride.

I switched to high gear and tried mounting. What a disaster! I usually do a rolling mount, but my pacing is all off because the cranks do not rotate with the wheel-duh!

I switched to a tire-grab mount, which got me on top of the wheel. I set off, but the tire did not and I ended up stepping off the unicycle. I repeated this comic dance several times before I gave up. The tire just does not want to move in high gear.

I regressed to an assisted mount holding onto a garbage can. Now I could get up, and starting off gently allowed me to get the tire moving. Unfortunately, my reflexes were all wrong, the tire moved too fast on my down stroke (1.5 times!) and I ended up stepping off the back. I repeated this mount several times and eventually managed to stay on for a few pedal strokes. At that point I started to get the hang of it and mounted and rode until I could ride around the block in high gear. It is much more sensitive to balance than in low gear, and I did a number of low speed UPD, most commonly stepping off the front when my attempt to accelerated failed.

The next day I rode around the block in low gear and in high gear and then tried shifting. I began in low gear with a rolling mount, and managed to shift to high gear by twisting my right ankle in until it rubbed the button. After 2-4 strokes this shifted it into high gear, and I immediately fell off. I downshifted, started again and once again managed to shift. This time I stayed on! I practiced this a few more times, mainly managing to ride through the shift.

I tried the same foot sweep to downshift and it eventually worked. I rode around the block, which includes a very small hill, and upshifted and downshifted a number of times successfully. This is a very cool unicycle!

I am shifting by positioning my heel to hit the crank. Sometimes it shifts on the first round, but more often the shift comes after a few strokes. I assume I will be able to manage it better with practice. I am shifting at very slow speed. Is this typical, or do some of you shift at high speeds? My shoe size, 10.5 (American) works fine shifting with the 150 cranks.

I am used to shorter cranks on my 36, but high gear with 150 cranks is a bit dodgy for control at this point. I basically must hold the seat so I can accelerate the unicycles out of precarious situations. I know some of you use 165 cranks for a 36 Schlumpf, and I can see why. I will stick with 150 cranks for the time being, but I am riding very cautiously.

Do you have any words of wisdom for a Schlumpf beginner?



Shifter Button Placement

Here are pictures of the shifter button positions. The silver button is too far out. I plan to move it in. Is the gold button OK, or should I move it in?

Thank you for the advice.


Scott, for ease of shifting, I recommend you keep the knobs where they are. 1mm in is just a tiny bit harder. Shifting can be smooth like butter and happen right when you think “Shift now”. It is a great feeling. I am still not at 100% but getting closer. Over the first 500 miles, progress felt slow then I got better.

Always start in low gear, even if you can mount in high gear and have to shift up right away.

When coming to a stop in high gear, get in the habit of shifting down - for practice.

Keep at it. I approached it as a new skill to learn. With over 10k miles of ungeared 36er riding experience, I was a total beginner when I got the Schlumpf. I looked at that as a good thing.


You are doing well. With your progress you will soon be an expert. You might also want to check out this thread on Schlumpf Shifting Techniques:

Welcome to the club.


I often wish I could go back to the days, starting from when i could first ride down the driveway, and experience again the joy of learning all those early, basic skills.

But short of a very “lucky” konk on the head, I can’t. I’ve learned lots of other skills in various specialty areas of unicycling, but most of those feel fairly specialized as well. Mastering the Schlumpf, especially at 36", brings me most of the way back to learning those beginner skills again. But it’s kind of better, because it’s what I consider very advanced beginning skills.

So the point is, enjoy this time, as you learn some new “beginning” skills. At first it will seem super-hard, but it will gradually get easier. The process is very rewarding, and keeps getting better for me (not counting this hiatus while I await a repaired hub). Just like learning to ride, only over a much longer period of time for most of us. :slight_smile:

Yes, free-mounting in high gear is also a skill, and may take a while to figure out. Generally, a 36" in high gear is a very touchy vehicle to control under 8mph or so. 10 is even better.

John, I thought for sure you would have something to say about Scott’s comments about crank length and how “he can see why some people use 165mm cranks on a 36er Schlumpf” because I took Corbin’s advice (in thread that Geoff linked to) having 9.5 shoe size and ordered the 150 cranks on my KH36G so I could “reach” the shift button. This, despite my love affair with the 165’s that I had “temporarily” put on my Impulse to prepare for the Schlumpf. Hearing Scott say the 150’s were “a bit dodgy for control” is a little worrisome. I can tell you that I loved the 150 hole on my original Impulse build and regretted the switch to 125/110’s so much (up the hills near the house) that I went full tilt got the 165’s. The good news is that I found my perfect un-geared length in the second (137mm) hole. So now, I own all three sets (165/137, 150/125, & 125/110) of KH dual hole Moment cranks. Putting the 125/110’s back on my Impulse and sticking with the 150/125’s on my KH36G as long as I can (until temptation and frustration gets the best of me and I have my LBS do the switch) hopefully without stripping the bolt (at this point, I only trust Bronson to touch my baby). More to come…

Thank you all for the encouragement. I did a second short round of riding around the block shifting today and found it easier. I also decided I was not going to fall all the time and went ahead and mounted handle bars and brakes.

I did not heed Nathan’s advice: I rotated the shifter buttons in just a bit to bring the backs closer to flush with the cranks when extended. I have been moving my heel over and letting it swipe the cranks. The right cranks was farther out and I noticed it caught my heel when I tried to swipe it. Now that I have brought it in just a little bit it does not catch my heel, but it still shifts.

The 150 cranks are not bad in high gear. The first ten minutes it felt like a whole new skill, and I would stand up on the cranks and over-correct like mad to keep on it. (Actually, the first ten minutes I did not stay on it. It was the second ten minutes where I started to keep above the wheel.) Now with an hour of riding under my belt it is feeling better. I am relaxing in the seat and only putting a bit of power into the cranks rather than madly overcorrecting. Any little hill has me up and out of the seat. David, I would suggest just giving 150 cranks a try and don’t be too hard on yourself at the beginning.

It is coming along quickly. I will try one of my typical 12 mile rides tomorrow morning to see how well I can manage it. If worst comes to worst I can always ride the whole thing in low gear. Instead I will try to take the flats in high gear and the hills in low gear. It should be an adventure! :slight_smile:


As for crank arm length, I think my only experience with Schlumpfs is with 150s. At least on 36" wheels. I actually was trying to get a pair of 160s for my century ride in Tahoe. I even bought a pair of Koxx Ones from Renegade, but returned them because they were too straight. I want Q-factor on any cranks used with a Schlumpf! I figured a longer crank would be better for non-level riding, though it would be pretty lousy in low gear.

My new 36 is gettting built this week. So I am reading this thread with a lot of interest and trepidation. It’s encouraging to hear your learning experiences Scott, and tell us how you 12 mile ride goes.

I am interested to know what protective gear you wear. Coming off the 36 in high gear might be too fast to run off. I was thinking about borrowing my son’s motorcycle jacket, with padded shoulders, elbow and back.

Surely, you have some upper body protection?

Here (see link below) is a good thread on safety gear. I wear FiveTen Impact High boots, SixSixOne EVO shin, POC Joint VPD knee & elbow, KH Pulse glove on left (braking) hand, DocMeter FlexMeter wrist guard on right (disc golf) hand, and a brain bucket. I did wear my old (grew up on a Suzuki RM 125) motorcycle shoulder/chest/back vest in my early days of 36er learning but it’s too hot / humid to wear all that gear in the summer. Now, I only wear a helmet, shin guards, and wrist guards (the most important IMHO) unless I’m pushing my limits in a race with my two wheeled brethren.


Thanks Dave, I think I have everything covered. The summer motorcycle jacket should still be good as it’s still cool in Sydney. And I have ordered some KH arm armour, and Hillbilly pants for the summer.

Thanks again,

Slow riding in high gear

My new Schlumpf hub now has 27 miles on it. It is a 36”, and probably only 10 miles of the total is in high gear. My shifts are better, but I still come off some of the time, especially when I am tired. When I UDP on an up shift, it almost invariably involves stepping off the back. So far all my UPDs have been at low speed onto my feet. The key to a successful up shift seems to be pedaling gently at modest speed to shift. If I am pedaling too hard, I step on the pedal as the gears shift and that sends the unicycle spinning out in front of me.

The downshifts have not really been a problem. I just take the speed way down and then rub the shifter button with my heel until the shift happens. I spin up the pedals to match the wheel speed, but as long as the speed is low it works fine.

The hard part is riding in high gear. I overcompensate and try to fight the unicycle into submission, and it takes a lot of energy. It reminds me of first learning to ride, where we all stood on the pedals too much. Some of the time I am able to relax into the seat and gently push the pedals and everything goes fine. The balance envelope is a lot narrower than with an ungeared 36”, and it is taking me time to get the feel of it. I need to remind myself to lean farther forward to balance out the force from pedaling.

I notice the unicycle sways more from side-to-side than I am used to on a 36”. Taking one hand off the handlebars helps with the balance. I am not yet confident (at all!), but it is coming along.

My normal speed on one of the flat courses is about 12 mph average. With my new spiffy KH-Schlumpf unicycle I did the same route with an average speed of 9.9 mph. Wow! I may actually ride slower in high gear than in low gear at this point! :astonished: There are places where high-gear riding is starting to come together, but I am not a speed demon yet.

Regarding protective gear, I always use wrist guards, a helmet and shoes for 36” riding. For my new unicycle I have added kneepads and wrist pads. In the past I have left a bit of skin on the road in UPDs. I hope the extra pads will help. My high-speed crashes have been about 14 mph, and I cannot get to the speed yet in high gear. Eventually my speed will kick up, and then I can see how well the extra pads work. (A motorcycle jacket sounds hot.)


The flat outer rim of the buttons needs to be inside the crank hole, this prevents the shifting rod that goes through the axle from getting bent or broken.

It also helps avoid accidental shifts, which are very dangerous when in high gear.

I’m starting to relax more and more on my rides in high gear. It’s still harder to do simple things like look over my shoulder at traffic. Down shifting at lights is a challenge, but sometimes I nail it right away. Up shifting is getting pretty good. I’m usually more tired after a ride on the Schlumpf, but hill climbing is a breeze since I use low gear. I don’t usually go faster than 10 mph out of fear of crashing. I can’t run that fast.

I’m seriously thinking of a geared 29, but my husband cries at the mention :roll_eyes: , so I guess it will be awhile. I’m supposed to visit a friend in Orange County in the next week or so. I’ll let you know if I’m coming down. Have you tried a smaller geared wheel? you are welcome to take mine for a spin to compare.

Hi Heather,

PM to let me know when you will be in town. We could go for a ride, although I do work days. We could see if others are interested in joining us, and I could loan you a unicycle if you do not have your favorite type available.


I tried 165s to start and it was way too hard to reach the buttons, and that’s with sz 13 flippers, so I moved the pedals to 135 and it was so much easier to shift, but that is way too short of a crank length for me, sooo I just ordered some 150 Venture 2, should have those for this weekend.

The shifting thing works, but 1.5 is a big step up, kinda leaves me wondering if 1.3 might be more usable, at least for off road. I like the 26" wheel, but my favorite wheel size for fast trails is a 29, which unfortunately would be way to tall geared up to 44".

I initially thought the same thing some years ago when prototyping the first KH/Schlumpf hub - 1.5 seemed like too big a jump and 1.3 felt like it might be better. But now after lots of time spent on it, the 1.5 ratio (on a 26) feels natural, and I think 1.3 would feel unnecessarily slow on easy sections. In an ideal world perhaps both versions could be made available but that won’t happen for the foreseeable future, given the small market.

So I do think it is worth working through the initial frustrations of the overly big feeling gear, at first, on a 26 offroad. Personally I find a geared 29 too big for my local riding areas, but that certainly depends on the terrain and the rider.


That’s probably true Kris, I’ll adjust some, but it really is quiet a jump esp if you compare it to internally geared bike hubs with gearing steps at 33% on a three speed and 13.6% on a Rohloff Speedhub 14 speed.

Considering the weight and size being what it is, how much additional “space” would be required to make the hub a 3 speed? That’s the dream right, to keep going up in gears :slight_smile:

I had decent luck changing gears last night, need to get a lot more consistant in making changes right when I want them, that’ll make true off road riding practical, so for now I’m sticking to double track.

I already miss my 29er, I find the 26" wheel a tad small and twitchy, which is why I’d take a 29er with a 33% step, cuz then I could have my cake and …

I’m glad I kept my 29er, it’s so light and quick!