Help! Stuck Schlumpf Shifter Button


This is why I am afraid to use the lightweight qu-ax cranks. I wish there were more lightweight ISIS cranks that had the same q factor as the KH moments. The Moments have the perfect amount of Q for use with shifting. They are so heavy though as you know.

I would recommend looking into the Onza Tensiles - 140mm ISIS if you want to save some weight. They are lighter than the moments by quite a bit(it seems) and have about the same Q. You of course loose that extra 5mm of torque that the 145 lightweight qu-ax cranks had, but you don’t have to be as afraid of accidental shifting.

You can also do what Joe said above and get the pedal spacer, but at the same time I don’t think this provides as much security as a tapered crank.

I am going to stick with the 150mm dual drilled Moments for my KH/Schlumpf 36, and if I don’t like them, I may try out the Onza tensiles or maybe even the 170/175mm lightweight qu-ax cranks that have some Q factor to ease the force on my knees. I just need my hub back from Florian, it has been forever!

i dont think i would care so much about the weight on my cranks but more on the problem that the cranks are too long.
with the new kh 127/110 dual cranks there is a choice on strong cranks that are short.

still i would like to see somewhone ride a geared hub with 80mm or something similar cranks but perhaps we will see that come within a few weeks;)

From what I hear, 150mm is about right for the geared 36.

I have tried a geared 36 with both 125 and 150mm cranks and the 150s felt infinitely better. 140s MAY be better, but anything shorter probably isn’t ideal for road use. Maybe for record setting use shorter cranks could come in handy, but I am not sure at this point until I get a lot more experience on a geared 36. I really want my hub back, there are so many things I want to experiment with.

I agree that 80 mm sounds very short for a geared 36", but Sander didn’t say 36", he just said geared. Moreover, for a number of years now there has been a downward trend in crank length. When Coker came out with the original Big One, I think 150 mm was the standard crank size. Now almost everyone with some experience on a big wheel considers 150 mm too long for an ungeared general use 36". Similarly, when I bought my first 24" MUni, I got it with the standard 170 mm cranks. I now have a KH24" and since I like long cranks, I have the 165’s on. It’s the longest there is from KH, whose standard for 24" MUni is now 150 mm.

A wordy way to say: 150 mm may be considered now to be “about right” for a geared 36", but I think that in a few years the consensus will drift towards shorter cranks. It’s telling that KH now comes out with 127/114 dual moment cranks, after the 165/137 and 150/125.

Several people in RTL, including at least one of the German Speeders, rode 125mm cranks on geared 36ers. I’ve ridden that way briefly, and it’s not that hard to get used to.

I do think we’re trending towards shorter crank lengths, but if we get gearing up to 2:1 or higher, I think you’ll see longer crank lengths make a comeback. Short cranks are inefficient from a biomechanical standpoint.

I agree - but we can’t get ratios of 2:1 or higher with a single epicyclic hub such as a Schlumpf (or similar, like Harper’s or Frank Bonsch’s hubs). But indeed with such high gears we’ll see longer cranks just as on bikes. Biomechanically such setups would be better but the gearing might be more complicated and/or vulnerable, and they might have more internal friction too.

Apart from the biomechanical advantage of longer cranks, comparing various setups is where the Total Gear Ratio comes into its own.

No, but you can with one of Pete’s jackshaft designs.

This is true, Arne and Jan rode with 125s. Chuck and Corbin were using 150s though.

I tried out Chuck’s uni and was able to try both the 150s and the 125s because he had the dual drilled cranks. You are right that 125s are not that hard to get used to, but they really aren’t as comfortable to ride with (based on my short experience with both sizes). I also think that short cranks + big gears + heavy wheel = bad news for knees.

I think it’s also dependent on your leg length and riding style.

Bicyclists have been debating it for years, even though they’re crank lengths don’t vary alot…

It makes no sense to me that bike crank lengths only vary by about 15-20mm at most…the pedalling circles are vastly different between someone 160cm tall vs 190cm tall. Gears don’t compensate for very different pedalling dynamics.

I’ll second the 150mm love. I’ll third it, too… I swear by my 150s. Though they do get in my way at times when I’m really trying to spin fast, they make a good cruising speed so much easier (than 125s) on my legs that I can go maybe 90% as fast for four times the distance. It’s a deal for me.

That said, I have given my 125s a try, and have maybe 50 miles of road riding with them. 20 of those miles were the fastest road miles I’ve ever put in on my uni, and the other 30 were painful and kind of miserable. Whadd’ya know. :=P The 125s weren’t too hard to get used to, and they were decently manageable, and allowed me to get a whole lot more RPM, to the point where 21-22 mph was sustainable for medium-long periods (like, longer than 20 minutes, probably less than an hour). That said, as soon as the wind kicked up, my pace went way down (to around 16mph) and it was HARD to push myself through the air. On 150s, it takes a LOT of wind to punch me under 17mph, while in good wind, 19-21mph is the fastest I usually spin, and neither speed really hurts, where as both speeds on the 125s were pretty tough, good wind or not. So… 125 is too short for me for now. I’ve had a taste of what shorter cranks feel like, and in the ideal situation with no wind and flat ground, I’m faster, and die sooner. It’s awesome to go so fast, but it’s not worth the quick bonk. Besides, the solution is not short cranks; the solution is higher gears. Riding on them, I’m definitely faster, but my spin feels ludicrously tiny, to the point where I think “what the heck am I doing on these?!?” I’d put up with ludicrously tiny if it made me faster in all cases, but any time I need to muscle the thing, it’s leg death or first gear, and I bonk after 20 miles instead of 50 or 60. If I’m in any kind of race with hills, even one like Unicon’s marathon, it’s 150s. If I’m going around a wooden track for one hour, and only one hour, then I think I’d go 125. I don’t know how the German Speeders pushed their gears with those tiny cranks; I have new respect for them after trying that out myself. I really run out of energy a lot faster.

I might try 137s, but I’m afraid to take my 150/125 moments off, because every time I put them on and tighten them, it seems that they press further into the splines. I have less than a millimeter of clearance between the cranks and the bearing holders now.

Nope, the freewheeling hub problem is not to do with the button being screwed in too far, because I reproduced the problem a few times with the button screwed quite far out.

Any ideas? I’m thinking maybe one of the inner springs might not be working properly and pushing the gear into engagement. It might not happen for ages, and then all of a sudden every shift or every second shift is goes into freewheel. Only seems to happen from high gear shifting into low gear.

Check out these videos. Explains what I mean:

Freewheeling Schlumpf (2.01 MB)

Freewheeling Schlumpf (2.17 MB)

Ken, your videos prove what you say. Too bad there’s no quick fix for you (and contrary to what I expected but what do I know). Has Florian ever responded to your questions? Otherwise, I’m out of suggestions other than to send the hub to Florian to have it checked, which will probably last painfully long.

Yep, I’ve been discussing this with Florian and once we work out what’s wrong I’ll post it here.

I think I have worked out how to reproduce the problem. If I push the button in hard (all the way in) and hold it there whilst still spinning the crank, it get’s into the deadzone where the gears don’t lock. The button doesn’t spring back out to lock the gear in place, it just get locked in this ‘pushed all the way in’ position. Maybe something is catching?

And here is the answer from the man himself:

"it seems, that there is some bad friction between axle bolt and gear shift
If you can wait a few days, I’d like to send you two pairs of bolts and
buttons with more play, to make sure, that they don’t have any influence on
the shifting process.
We slightly changed the tolerances during the first few monthes of
production, so I could imagine, that the problem has its origin in a pair of
bolts and a pair of buttons, that weren’t checked together.

Is this o.k. for you?"

Florian is awesome. Cheers :stuck_out_tongue:

Ken’s last two replies are comprehensible if you assume that the button needs to be at a specific (spring-loaded?) position for the gear to lock.

This surprised me, and I wasn’t ready to assume that. I just checked my own Schlumpf (moderately old type: square taper but the high number of engagement positions). I have about 1 mm of play on each side, by which I mean that each button can be pushed in against a spring about 1 mm more than the normal pushed-in position. But if I continue pushing in and turn the cranks, the coresponding gear (high for gold, low for silver) stays locked.

So is this dead zone something specific to the newer splined hub? I wouldn’t think so since I’ve always understood that the internals are the same between the two versions. :thinking:

If it’s friction between the shift buttons and the crank bolt, couldn’t you try shifting without the buttons on the wheel by pushing with a thin tool to see if the fail disappears. If shifting then works fine, you and Florian are on the right track. Might save a few days.

That’s what Florian asked me to do, and that’s what I did. I spent about 5-10min trying to reproduce the problem after taking off the button and nut. And I couldn’t.

After that I screwed the nut and button back on and worked out that I could reproduce the problem exactly when I push the button hard (all the way in), whilst turning the cranks. It needs to spring back about a mm or two for the gear to lock. Otherwise, the button seems to get stuck in this hypershifted position and doesn’t come back out that mm to lock the gears with.

From what Florian is saying, there needs to be more play between the button and axle nut, otherwise it could potentially get stuck in this position. That’s why he’s sending me new nuts and buttons.

Hope that made sense.

can you sand alittle off the shaft or buttons ? Just to get by !

I broke my crankarm the other day. Now I have to take off the cranks.

I never touch my cranks until today. I can’t even take the button off.
I used the tools it came with but it seemed to be stripped right away- on both sides.

I got it from UDC…it an original
So if I can hold one button I can loosen the other?

screw extractor sounds like a option

Mine looks like that one but it doesn’t look amputated.
I do see metal filings when I check the 1.5 allen wrench:(

Thanks for the special tools, Schlumpf…NOT
It didn’t help me or I’m too stupid.