Schlumpf Question/Issue

I’m not sure how to word this properly.

I bought a hub back in June/July last year. Shipped to me at the end of October and I only really tried to get on it a couple times after I had my wheel built since it started getting too cold to ride.

I just pulled it out again today and moved my pedal to the longer crank position since I remembered that I couldn’t get moving when it was in 1.55. The part I think that’s bugging me the most is that there’s probably a couple MM that feels like the pedal needs to move before the gears lock and the wheels start turning. It’s making it hard to start moving.

Is this a defect? I’m going to paste what Florian told me and maybe one of you will be able to confirm for me that me and Florian were talking about the same thing. It almost sounds like he’s talking about the shirt button itself, when I’m referring to feeling the gears lock… which i’m wondering is meant by “play”

Florian’s response…
The only thing the mechanic can do wrong is the position of the gear shift buttons.
Correct adjustment is:

  • In the pushed position, there is still some play (you can push the button more inside). Not important how much, less than 1mm is o.k.
  • The buttons are installed too far outside (they are no longer guided by the axle bolt). So you feel a lot of play and by pushing it a resistance.
  • If there is no play underneath the button, the shifting shaft can’t do all the way for proper engagement of the clutch.

Just to mention: if the axle bolts aren’t tightened enough, they can come lose and limit the play of the buttons.

Thank you all for the help! I don’t know what some of the parts he’s referring to are, so please talk to me like I’m a noob.

Sit tight, I’m uploading a video

Video. Thanks again to the future people that help me with this

My understanding is that a couple mm of play/slop is in every Schlumpf hub. That is the case with mine.

I just watched your video, and your hub is fine.

The way I understand there is a collar that alternately locks the spindle to the hub shell, or the planet gear carrier. It disengages from one before engaging the other with good solid medal pins rather than a clutch system. It makes binding impossible and is a very robust system but results in a defined amount of free play before the hub re-engages in the other gear.

It’s why many people give their pedals a little extra kick on upshift and do a short hesitation on downshift to get things engaged faster. It’s a spooky feeling when things don’t engage right away.

Thank you both. I’ll have to mess with it outside tomorrow. Sounds like I should move it while dismounted a bit so it locks in place before I jump on it. At least until i get used to it.

I’m debating of buying longer crank arms too, but I’m confused as to what I have now. I measured the 2 holes earlier and they’re about 195mm / 230mm. I don’t see those sold anywhere. I have whatever was standard on the KH 29" Muni with the brakes, which says “127/150mm”. Am I going crazy?

Just watched the video and yes your hub works the way it should. When you press the button the cranks disengage from the gears, they then need to travel forward to catch the next gear up (or down). So there’s a few milliseconds during which you’re essentially freewheeling. Once you get used to it, it’s no problem but during the learning phase of shifting (it can last a while, I’ve had mine for a long time…), it’s scary and if you’re not in the “slow falling forward riding” position, the wheel shoots in front of you. It’s even worse in downshifting because there is a massive difference between the gears, so all of a sudden you feel like you’re pedaling like a maniac!

To get used to the high gear, you should indeed engage it and then mount the uni. And maybe use a fence/wall until you get better at it, or at least your brain gets it.

I think without that play the gear shifting wouldn’t even work, you need it to help the gears engage just like an old Sturmey :smiley:

If I shift the gear when I’m not on the uni, I give the pedals a quick push with my foot to re-engage the gear before mounting, otherwise I’ll get a big jolt!

I tried it today and was able to get going after I moved it in place. I still notice it when I have to slow or I guess back-pedal slightly. It’s not nearly as bad but I just picture it wearing away at the gears eventually.

I believe the Schlumpf manual says you should be able to rotate the pedals all the way round without the wheel moving at all, by clicking it through the gears 20 (or 24?) times, so that should give you some idea of how much play to expect when shifting the gear.

The play when it’s actually in gear is also not too much of a problem, you should always have a bit there otherwise the gears would all jam up and you’d get nowhere, this is the same for any geared hub but is obviously far more noticable on a fixed unicycle. Just keep the hub well-greased and you’ll be fine :slight_smile:

As others have mentioned the issue you’re having is a fundamental feature of how the hub works, and it wouldn’t be able to operate otherwise. Just to give a bit more detail, there are dog clutches connecting the drive either direct to the hub shell or to the gear train - dog clutches don’t provide instant engagement, they have to rotate a bit until the teeth engage. Also, you can’t have both clutches engaged at once otherwise the whole thing would lock up, so one has to disengage before the other engages.

In practice it’s something you get used to relatively quickly - the freewheel on gear change is something I don’t really notice any more, and I’m far from an expert Schlumpf rider. You just make sure you’re in balance over the wheel when you shift.