Schlumpf hub bolt

Replacing the KH moment hub to Schlumpf hub on my KH 24 wheel wasn’t a big deal but installing the cranks have proven to be a different story.

The left side went in fairly easy, few hits with plastic hammer and 50 Nm torque went all the way in. However after few re-adjustment the 6 mm allen is getting a bit rounded.

The right side crank has been a nightmare. I have hammered many times, seems more like a carpenter job. Still is not there and i used the torque wrench to help but I managed to really make the 6 mm allen rounded. I made same bolt but with 8 mm allen and is working much better but still this crank is far from reaching the proper seating position against the hub.

Two questions:

  1. Why not use 8 mm instead, they are harder to damage?
  2. The head of the bolt is 3mm thick, why not to make it of 5 mm which still provides enough room to hide the shifting buttoms and gives more strenght to the bolt.

It is just me having this problem? :thinking:


I had this same issue. You should look into a different hex tool for tightening your cranks. You also may be putting too much force. 50nm (even though that is the spec, is pretty high). The key to getting your cranks to stay put is to tighten them, ride, tighten, ride, tighten ride, until they stop coming loose. When I put new cranks on the kh/schlumpf hub, I leave the buttons off so that I can ride for a mile and then slightly tighten the cranks and repeat for about 3-4 times before I put the buttons on.

Order some spare bolts from Florian and replace them before you round out the hex hole. I found that the 6mm hex tool that shipped with the hub did not fit securely in the bolt (there was some movement when trying to tighten), and this led to my bolts beginning to round out. I immediately bought a properly sized high quality hex attachment for a socket wrench, and this has worked wonders ever since.

what is Florian email address?

info at schlumpf dot ch

you can get it from his website too

Florian already answered my email related to this bolt with his comments. He will send me a couple of bolts and the size and characteristics of this bolt is the best compromise in his opinion - and since he is the man - then he has to correct.

Florian, if you read this - many thanks again!:smiley:


Great, yeah Florian is the man! Be sure to also get a new 6mm hex tool (the one you are using might be of poor quality) and make sure there is no movement inside the bolt when you are trying to tighten.