Schlumpf in a steel Nimbus frame

Hey, I’m a bit confused with Schlumpf frame compatibility. I guess I figured that as long as both were the same width, life was good.

Anyway, I’m curious about sticking a Schlumpf hub in a steel Nimbus frame (like the black round crown they offer that comes on the Drak/Road). Will it work without modification? Or is grinding something going to be neccessary?


theoretically it would work but I would not trust the steel bearing caps to hold the knurled bearing in place. If you have a spare aluminum bearing holder that would fit it might make sense to put it on the knurled side for increased grip.

There are some adhesives that might also work, but if I were to glue the knurled bearing to a bearing cap it would be one that fits multiple frame types like a D’brake or Mountain Uni UCM, which are aluminum anyway.

Terry “Unigeezer” Peterson suggested putting a strip of aluminum tape inside the bearing cup on the knurled side to give it more grip. I did that, and have had no slipping problems. (Except one time when I accidentally let the cap bolts get really loose.) So you could try that.
As far as modifying the frame goes, I wouldn’t be surprised if it needed some grinding to fit. But if you have asscess to a belt sander or body grinder it goes pretty quick. I also found that different crank arms work with different degrees of success. Schlumpf recommends KH Moments (at least, earlier they did, they might have changed the recommendation to Spirits now, since Moments are scarce.) Anyway, I had to do a bit more grinding to get my M4Os to clear, so just something to watch out for.
cheers! (and looking forward to pictures of this new creation)

The new generation of Schlumpf coming end of this year will be narrower and thus, will have more frame clearance. Florian said, that this will improve the compatibility to frames other than KH. So no grinding necessary.

The other point about the new Schlumpf will be about the knurled surface around the bearing. There will be an improvement. so we can’t tell yet how well the combination with a steel bearing cap will work with the new solution.

Also you have to look at the diameter of the inner shoulder of the frames bearing housing: minimum 38mm! (see here)

But, do you really want to combine the heavy Schlumpf with a heavy steel frame? Don’t get me wrong, I like steel frames, but for my probably planned Schlumpf project, even I would take an aluminium frame.

It works with modification. I modified my friend’s Nimbus frame last year to fit his Schlumpf. You just have to grind down the inner lip.

As everyone said, it slips easier since it’s a steel frame and it’s not as soft as aluminum. There’s a way to adapt your riding style to the slipage though. If that stops you from having a schlumpf though… It’s not a good excuse :stuck_out_tongue:

I prefer steel, but Id just as soon use an oracle frame to not have to grind and worry about slippage.

There shouldnt be any issue drilling the frame crown on an oracle to use a sidepull brake should there?

The schlumpf would probably an older one since Id rather try to find one used (save a little money).

I’ve had one in a chromoly 36 frame (Hunter) for quite some time. I torque the bolts to spec and have had zero issues. It has a rim brake on it.

Jakob has a style where he brakes REALLY hard- and he uses a disc brake on his. He’s crazy fast too. For most mere mortals there shouldn’t be an issue and you won’t have to modify your style if you follow the torque spec.

Again, don’t let it stop you from getting a Schlumpf.

This would be a road only setup (pavement and gravel) I don’t really intend on Muni with it.

Either way though it sounds like a Nimbus frame (even a steel one) will require some grinding, correct?

Most likely. Even the KH frames require grinding the inner lip for the current generation hubs.

What a pita. I know new gen hubs will have more clearance but its crazy that existing ones are that tight.

Hey Killian

Here’s two pics of my steel nimbus frame before and after. Can’t remember which size frame as I ‘dremmelled’ both my 29" and 24" frames.
I tightened the bolts etc to the correct torque and had no problems with slipping.
I have not put the uni’s through lots of abuse since then apart from lots of dropping on the ground and the hub is still okay.
I’m now building the hub into a 26" wheel and waiting till the KH26" frames are back in stock.

Hope this helps. BTW it was easy to do…BUT don’t do what I did with my 24" frame and grind the wrong side of the bearing holders ( doh ! )



I’m sure the lip doesn’t need to be as deep as it is made. You can just say you were trimming a bit of the excess weight :wink:

I used a steel Nimbus Nightrider frame with a schlumpf on the lands end to John O’Groats ride. It did take more careful setting up than aluminium frames to get the hub set up correctly.

The new hubs will be great. I am looking forward to the version with the internal disc fitting.


Will the new ones be more 'plug ‘n play’ for users of non-KH frames? :smiley:

Sounds like I need to start saving my pennies!

Pretty well compatible with existing frames. On the Oracle 36" the lower bearing housing will either need modifying on one side (inner lip removed to 42mm) or you will use the one we supply with hub (that is the plan anyway… lets see).


Sounds awesome!

Definately going to start saving for a G29 build! :D:D

Me too. Hoping that it will be compatible with the QX frame.

The “knurled side” of the hub, and the internal disc fitting, will they both be on the left side? And in case, the “old” d’brake disc brake mount will lock the hub proper for riding in high gear, I guess (after removing the inner lip)?

I guess further that the new hub with the internal disc fitting will suit the Oregon frame well…


The new design will not be using the knurling but will be locked in place with a crescent that can not pass in to the upper bearing housing. So my guess is that if the inner lip is removed on the brake mount then it would work as the locking piece. We will know more when the pre-production prototypes are produced and we see which frames it will fit in and how.

Roger, do you have any idea of when we can expect the new hub?