Advice On Slack In Kh-schlumpf?


I just received my khschlumpf built to a kh29 wheel by Roger. YESSSS!!!:slight_smile:
It arrived before I got around to grinding the bearing holder inner lip to size, so all I can do to play with my new toy is put on the cranks and adjust the buttons.

Having done this, I would like to ask for your collective wisdom on the following:

  1. I found there is a kind of slack when in direct/1:1 drive, a slight movement of the cranks which rock back and forth with a metallic “toc” sound at either en of each rock. Feels to the hand almost exactly like a loose square taper crank only with a definite sound. In your experiences, is this as it’s supposed to be? Does the movement increase with miles and wear?

  2. This is my first ISIS hub and I have found it really difficult to fit the cranks. Much more so than square tapers. I now have one on, but the other is only half way and I’m pretty sure I’ll ruin the crank bolt if I keep trying to screw the crank up the axle. The 6mm shallow allen hole feels flimsy compared to the usual 8mm…

thank you for your help,


For splined cranks you should hit them on most of the way with something that won’t damage them, and then screw the crank bolt in after.

I do not know anything about the other issue.

There is definitely a bit of slop in the gear train; that is expected behavior. When I idle in 1:1 mode, there’s a thunk at the bottom of each idle. It probably gets marginally worse over time, but you’ll get used to it.

I also found the cranks hard to install the first time, and stripped the 6mm allen bolt doing it. I think the tolerances are not very accurate on the KH Moment cranks (it could be the tolerances on the hub, but I trust Florian’s manufacturers more than the guys in Taiwan). They do get easier to install after use; one thing you could do is do a little bit of riding/hopping with them installed the way they are now, remove them and reinstall. It should be easier the second time. Definitely do what you can to hammer them in with a rubber or plastic mallet first, but even that probably won’t get them much further. Use grease on the hub splines.

Thank you for your replies.

Does anyone know if the axle is a single piece going straight through the mechanism? The expense of the whole thing is rather inhibiting when you stare the thing in the eye, heavy mallet in hand, and I find myself loath to really belt the cranks on…


Firstly, yes, the metallic ‘toc’ and slight play is normal. It really isn’t anything to worry about, and after the first 10 minutes riding, you won’t even notice it’s there. My Schlumpf (original square taper, not KH version) has several thousand miles on it now, and it really doesn’t seem to be any different. When I topped up the oil a few months back, the ‘toc’ sounded a bit more metalic than beforehand, but it didn’t seem to affect anything else.

The axle is made in one piece, so it should stand up to a bit of pounding. The scary bit for me is using a crank extractor to get the cranks off - if you don’t have the little sleeve thing the right way around, you’re in danger of mangling the gear shift rod and god knows what else! :astonished: