Help! Stuck Schlumpf Shifter Button

Ok, so I’ve had a few rides on my new Schlumpf and I tightened one shifter button a little too hard and it’s stuck. I can’ remove the little inner screw- I think I might have rounded it off trying.

Not a problem…it’s still rideable. At least until today, because now the crank is loose on that side. I don’t know how on earth I’m supposed to tighten that crank when the Schlumpf button is in the way, and stuck!!! :astonished:

Any ideas?



p/s Not related to the above, but on the other side, I snapped the mushroom dome of the Schlumpf button, so all I have is the bit that screws into the hub :frowning:

I wouldn’t know either how to tighten the crank with the button in the way. Those tiny screws are easily overtightened indeed, I had a similar issue as well. In my case, the Allen bit snapped during tightening. At first I didn’t notice the snapping, and it felt as if the screw was rounded. So - make sure your Allen bit is OK. If it is, the only other option I see is to drill out the little screw and get a replacement, carefully though or you might damage the threaded hole it sits in! That or sending it back to Florian who, if he has time, will perform some magic. Come to think of it, a third option is to ask some magic advice from Florian.

Not sure I understand what happened at the other side. Was it that the dome-shaped bigger part of the shifter button broke apart from the stem with which the button is tightened to the shifter shaft, so you only have the middle part still on? Man, you’re hard on the thing!

Is the new KH hub, or the original Schlumpf one? I know the original ones had two grooves in the top of the button and came with a special tool that fitted in there to hold it still whilst tightening the grub screw. If that’s the case, then you might be able to try to unscrew the whole button (which will take the grub screw with it) whilst holding the shattered remains of the other button with some big pliers. For that to work, however, the grub screw in the other button needs to be tighter than the one you can’t get out. :astonished:

An alternative would be to take off the broken button, and get hold of two very small nuts that fit on the shaft. If these are put on far enough, and tightened against each other, then that will give you a safer, easier way to hold the shaft whilst unscrewing the button with the stuck grub screw.

Or else, you could just buy a new hub… and I’ll pay the postage for you to send me the old one :slight_smile:


I have emailed Florian. Waiting for an answer but I’m in a bit of a hurry due to a pending record attempt in a couple of weeks :stuck_out_tongue:

How could you possibly snap the little inner bolt? Isn’t it inside the button?

I don’t think drilling is an option…

And yes, I broke the dome part where it connects to the stem. I haven’t actually ridden the Sclumpf much…probably only about 50-60km so far. A bit dissapointed that it just fell to bits when I tried to shift into gear.

It’s the new KH Schlumpf hub.

I was considering your first option, but if I tightened the broken grub screw on the other side, it would just jam that button in there instead of the one that is currently stuck!

I’m going to see if I can do your second option, but it means finding a very narrow pair of pliers to grip it I think.

Your third option is not feasible because I need it for a record attempt in two weeks time. Note that in order to get my KH 36" rideable, I actually had to buy a second frame because my first (brand new) frame ended up with a jammed seatpost. (see my earlier post on using pipe cutters)

I’m presuming you’ve rounded the allen key bolt, so the allen key just spins in it, it isn’t just that it is very tight?

If it is rounded, and unscrewing the other side doesn’t loosen it enough, the only option is to drill it out.

Unless you are very very exact, you need a new button, as you will destroy the button doing this. I had to do this, and I certainly needed a new button.

Be careful not to bugger the shifty shaft.

On other possible option is to use an easy-out / screw extractor. They are a left hand drill bit, basically you drill a little pilot hole with a normal drill bit, stick the easy out in, turn the drill to reverse, and they will dig in and unscrew the bolt (thanks to being left hand thread the drill action loosens the bolt) . You’d need to hold the button with pliers when you did this, or else it’d just screw it up. Hardware shops sell them. You’d need a pretty narrow one for a schlumpf screw though, and they are a bit brittle sometimes, so a bit risky. It will destroy the screw, but maybe not the button if you’re lucky.


I am tempted to replace the quote in my sig line with that bit of technical-speak… :slight_smile:

Sorry I don’t have any useful advice. If it is an allen hole, you might be able to file down a slightly larger allen key and tap it in with a hammer to get a tight fit and possibly be able to unscrew it.

hahahahahaha, yoink!

I second Joe Marshall’s recommendation. Use a screw extractor. I have removed bolts with them and they work if you are careful. They should be trivial to use if we are talking about an allen screw.

I can find screw extractors at the local hardware store.

I don’t own a Schlumpf so I don’t know exactly what they look like. If this is a set screw, often called a grub screw in other English speaking countries, it will have a centered guide hole to drill into and an extractor can be used as Joe suggested. This will be a tiny extractor and they are hardened steel so it will be brittle as Joe also said. They are generally used with a tap handle, not a drill, so you have some control.

One thing I have done with those pesky screws if you can’t grab them with pliers, vice grips, or some other tool, is to re-swage the broached hex hole in the screw. If the “shifty shaft” is strong enough, you can do this. It requires a drift punch to flatten the top of the set screw and the drift punch has to fit over the broached hex hole without exceeding the inner diameter of the threaded hole the screw goes into. If the screw sticks out a bit, this won’t matter. A sharp rap on the drift punch with a hammer will flatten the broached hex hole and the sides will curl in allowing the hex hole to grip the allen key again. This also loosens the thread contact grip and makes it easier to turn. Smack it and then test the allen key. Keep it up until you have a good fit.

I think I’ve figured out a way to unscrew it, but it will have to wait until tomorrow when I go to the bike shop, as I don’t have any pliers.

I’ll take off the button (or what’s left of it) on the opposite side to the stuck button. Wrap a cloth on the shifter shaft, and grab it with pliers. Hopefully that will hold it tight enough that I can unscrew the botton on the opposite side.

Will let you know how I get on.


That’s roughly the same as Spencer’s locknut idea. I think the locknut might be more likely to work though - I had a go at holding the other end in various ways, and didn’t manage it. The only thing I’d worry about with the locknut is being able to get in and undo it afterwards.

If you can get hold of some spare buttons and a drill, drilling it out really is easy and fast.

I’ve only done this once, I think I’ve got the knack of tightening them up nowadays.


Oh ok, I didn’t understand what Spencer was saying fully, now it makes sense. Problem will be trying to find the right sized nut to fit on the shaft.

Yeah, it’s probably the accent. I get that a lot :slight_smile:

Basically what you need to do is hold the shaft still whilst undoing the button, which will, in turn release the tension on the grub screw. The easiest way of holding the shaft will be with a cloth over it and some pliers - however I would be afraid of damaging the thread, and I don’t know if you can get to enough of the thread to get a firm hold on it.

If you put two nuts on the shaft, and tighten them up against each other, then this will form a really solid grip on the shaft, and you will be able to use a spanner to stop the shaft from turning while you undo the button on the other side.

The problem is going to be getting hold of two nuts of the right size. I know the KH Schulmpf hubs have a bigger shaft than the original hub, and I’m sure somewhere it’s on Florians web site. It’s probably M4 or M3, and most engineering supply shops should be able to get suitable nuts for you.


Edit - The size nuts you will need are M5

No I didn’t snap the little bolt. When I wrote I snapped the Allen bit, I actually meant the Allen bit:). See this pic, which is my broken one: the thin end broke off while I tightened the little screw. The Schlumpf procedure says to tighten “very firmly (1.1 Nm)”. I don’t have a torque screwdriver so I just guessed how tight it should be. Misguided by the words “very firmly”, I apparently guessed wrong.

When I later tried using this broken tool to undo the little screw (without realising the tool was amputated), it felt as if either the screw or the tool was rounded. That’s why I wrote “Check if your Allen tool is OK”. Florian sent a replacement Allen bit and all was good.


It’s for the KH Schlumpf hub, not the Road Schlumpf hub. It uses a 2.5mm allen key instead. Unfortunately, my hub never came with one, because it was confiscated from UDC by the airport when they were bringing it back to NZ. Apparently a 2.5mm allen key can be used as an offensive weapon :stuck_out_tongue:

Ah, now we (or at least: I) know that the little screws are different in the two hubs, because the bit that comes with the road hub is effectively a 1.5 mm allen key.

I guess then that the KH Schlumpf hub doesn’t come with a recommended tightening torque for that screw? Because to apply a specified torque you need a bit as opposed to a regular allen key, to put in your torque screwdriver, right?

50 Nm

But who on earth carries a torque lever in their toolkit anyway?

I want to throw the damn thing out the window. Just spent the last hour trying to hold the shfit shaft and unscrew the stuck button, now I think I’ve damaged the threads on it. Guni’s suck!

dang Ken, the seatpost/frame problem and now this, that has gotta be frustrating.

I was daydreaming about some long distance tours this morning - I wouldn’t want to have glitches like this out in the middle of nowhere.

Depressing indeed. Geared unicycles may suck but they’re faster. Maybe that sucks too…

But 50 Nm?? Maybe that’s for the crank fixing screw? Sounds like way too much for the screw to fix the button. If you did that to yours… no wonder you damaged it!