Schlumpf hubs: general discussion

Thread jack aside, I always bring a pump with me. When I go for a muni ride, I run a relatively high pressure in my 26" X 3" tire for the approach and ascent (25-30 psi), let air out for the descent (~ 18 psi) and then maybe/maybe not pump it back up for the return.

Thanks for the input.

I don’t understand what’s a thread jack. It’s a question related to using the Schlumpf. Where else do you want me to ask?

No criticism on my part. Really. :):):):):):slight_smile: I’d just as soon answer that question here as anywhere else. But strictly speaking, muni tire pressure is an independent topic. My KH 26 doesn’t have a Schlumpf but the topic is just as relevant to my riding as someone who does have a Schlumpf. No big deal. Maybe next time I head down to the bay area we can go for a ride. (Now THAT’S a thread jack.)


Do you come down here often? I’m coming to Oregon last week of July. Now we’ve really jacked this thread.

Backing away from the absolute thread jack to the semi-jack. . .

I think tire pressure is something of a Schlumpf topic, in the context of mixed road/trail riding. I always carry a pump anyway, along with tools and both patches and a spare tube. For typical mixed riding (pavement to trail, unpaved bumpy trail, then pavement away from trail) I think it is worth carrying a pump and changing pressure if the distances are of any significance. It only takes moments to reduce tire pressure, and not much longer to pump it back up with a decent pump.

Well, it’s ugly, but I can now shift on the fly. My metallic growth allows me to activate the button while riding. Shifting is surprisingly not that hard. It’s still kind of freaky to think about when I’m ready to go for it. Now I need to create a “growth” for my left foot. I figure when I hit the trails I’ll take them off so I won’t accidentally shift.

The first two pictures were failures as the spoon is too thin. The last three are successes but ugly. When I get comfortable with it all I will move the pedals to the 137 holes and hopefully not need anything more that my shoes.

Innovative solution! Yes you will find the 137 holes much easier.

—Nathan - 12 miles today, all shifts on first attempt without looking!

That’s cool mbalmer! Very inventive and persistent!

I started out using 150mm cranks on my KH24 GUni and while I could up/down shift adequately, it was never very instantaneous and it would typically take many crank revolutions to shift. However, recently I finally decided to try using 137mm cranks which would theoretically mimic a similar crank/wheel ratio that I’d gotten comfortable with on my (now sold) 26" MUni with 150mm cranks. I was right, felt so much faster with the 137mm and I still had plenty of control in the buff stuff. Best of all, my shifting has been so much easier that now I’ve gotten much better at quickly shifting depending on the trail terrain so I can squeeze in some high gear riding on easier sections of single track. With my small feet (men’s 8.5) the smaller cranks are much easier to shift with! No need for special devices as I just use the heel of my shoe, just angle it in there and bam! it shifts. Cake!

I hope 137s work easily for my feet (men’s 7 or women’s 8).

Some pages back there was a discussion about using spacers on a Schlumpf hub.

Yesterday I visited Florian’s factory, together with some other unicyclists, and I raised that question. Florians answer was very clear: Never use a spacer on this hub! The retaining clip can’t take the load and would be pressed against the bearings, which are again quite different from the bearings of a standard hub.

I was impressed by Florian’s quality standards. He explained the design of the unicycle hub in detail. And it looks like the next bunch of hubs will be available shortly.

Hugo, thanks much for providing this important information. This is really something that Florian should include in the manual for the hub. Unfortunatley, it seems to mean that the Mountainuni system is not truly compatible with the Schlumpf hub, at least not without significant risk of destroying the bearings.

The reason I felt confident to try a spacer with the hub is that it had the exact same profile as the portion of the KH crank which contacts the bearing otherwise. It seems to be working fine. I have the older hub, but I imagine his advice would be the same for that one, too.

Oh well, I knew the combo of the Schlumpf and the Mountainuni disc brake system was too good to be true.

I never saw any KH crank that contacts the bearing. I have plenty of space between the crank and the bearing, on both of my hubs. :thinking:

I am mistaken, Hugo. I noticed the spacer was the same shape as the inside of the crank, so just assumed it would sit there, next to the hub, the same way.

I was thinking the crank touches the bearing and was wrong about that.

Thanks for asking Florian about the issue. I’ll be disassembling that set-up ASAP.

Why do you need a crank-shaft spacer for the MU disk brake? Couldn’t you just mount the crank as usual, and then adjust the position of the brake and the disk so that they match well?

The position might not be completely stable when you changed cranks, but who cares? You would just need to do a fine adjustment with a crank change.

Is creep a problem?


I had the same question…

My impression from the Mountainuni thread is that the spacer is necessary to get the precise alignment correct. However, it does sound like it’s worth a shot for someone to try without the spacer if they already have a Schlumpf and the Mountainuni components. Might not work due to brake pad rub, but it shouldn’t harm the hub.

. . . calling all Steveyos. . .

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.