Schlumpf spoke gauge?

As far as I know this matter was not yet addressed on the, but plz correct me whether I’m wrong.

I am preparing to build my KH29" Schlumpf Guni and I want to build it using the strongest possible spokes available. I’ve found that DT Alpine 3 are very strong and are also available in the length appropriate for this wheel size from my local retailer. But they are 2,3mm thick.

What Schlumpf assembly manual says on the subject of spoke gauge: ‘The hub has 36 spokes holes, designed for 2mm spokes.’ But the spoke holes in the hub’s flange are 2,9mm in diameter, therefore virtually able to accomodate 2,3mm spokes.

My consequent question is:
(1) Is it okay to use 2,3mm spokes with the Schlumpf/KH Geared Hub?

I’d also love to know:
(2) What spokes are you using?
(3) Have you had any issues with the spokes you are using?
(4) What are the best/strongest Schlumpf-compatible spokes you’ve stumbled across?

Paulus Germanus

a) All of the above questions are directed to Schlumpf/KH users or/and those familiar with the subject.
b) Plz give all the measurements in mm.
(I am so much more familiar with the metric system. Thx :wink:

Why do you single out a single component (i.e. spokes) to be as strong as possible? Spokes need to ‘match’ the hub and rim (and nipples) for strength.

I am not an expert on this, but I think that a spoke should have some freedom to move in the spoke hole. Also, the spoke has an “elbow” that may extend into the part that goes in the hub, therefore requiring some slack in the diameter. Undue forces might be exerted on the hub if the fit is too right. I have heard of people breaking parts off the flange of the Schlumpf hub by too high spoke tension, maybe combined with the wrong type of spoke. That is a costly repair! The Schlumpf hub’s strength is adequate but it is not super strong. I recommend to stick to the spoke diameter in the Schlumpf manual. It must be there for a reason.

My wheel was built for me and I never checked. Just now I measured and my spokes seem to be 2.1 mm thick.

Yes, in my 36" wheel, 3 or 4 spokes have been broken since I have it (3.5 years). I ordered a bunch of spare spokes and replace broken ones.

The replacement ones (that I ordered from have held up nicely until now, but I have no idea about material or brand.

U see, I was reading quite a lot on the subject of spokes prior to starting this thread. What almost everyone seems to complain about in a bicycle, when it comes to the subject of spokes, is them breaking or stretching due to too high tensile forces. I automaticly assumed that if the forces are high enough to stretch or brake a spoke when the riders weight is distributed between two wheels, the case must be even more severe with only one wheel! Or am I missing sth there? :wink:

That is very true indeed. But I assumed that with the Schlumpf being quite durable and the KH29 Freeride rim being apparently bulletproof, the only thing to take care of now are the spokes.

I’ve also read about ppl plucking out the spokes from the flange damaging the hub. But the argument given was always the overtightening of spokes. I am not excluding wrong spoke type as a factor, but - as far as I know - it was just never mentioned.

Seems legit :wink: and I do believe that it may be so. But I’d love to get an opinion of someone who actually knows for certain how much slack is needed for the spoke to be safely installed in the hub, and whether the info in the manual about the spoke being 2mm is definitive.

Thanks 4 help Klaas Bil :slight_smile:

Firstly, I applaud you for doing (a lot of) research before posting.
Secondly, insofar I said that spokes should not be too strong, I take that back. As long as you don’t tighten them more than they should (whatever the ‘correct’ value is), it wouldn’t hurt if the spoke could handle more tension. In fact, if spokes break less, all the better.
As to diameter and slack/play in the spoke hole, I can’t say more than I did. Hopefully a real expert chimes in.

what Kris Holm has to say on the matter

I’ve asked Kris Holm about this:
‘The hub has a 2.9 mm spoke hole diameter; the manual says that “The hub has 36 spokes holes, designed for 2mm spokes.”
Can 2,3mm spokes be used without damaging the hub?’

This is the reply I’ve received:
‘The hub is designed for 14 Gauge (2.0 mm) spokes. Personally I have not used or tested 13 gauge (2.3) mm spokes in it. However, as long as the spokes fit through the hole OK and can be seated properly in the hole (which I believe should work OK), it should work just fine. As long as they fit well on installation, it should not damage the hub’

It was pretty amazing, getting the question answeard by Kris Holm himself!! :3 and I guess this finally settles the matter.

The only thing left to do now is to install 2,3mm spokes and test’em! :slight_smile:

I used Sapim Strong single butted 13/14 ga spokes on my Schlumpf hub/29er. They are 13 ga at the head and then taper to 14 ga down the length of the spoke. They fit great and felt like a much better match to the large-ish spoke holes in the hub. Sapim Strongs are hard to find locally, but you can get them through I’ve never had one break, no matter what I’ve done to them.

That said, you would probably be ok with straight ga 14 spokes as well. . . .but when you spend that much on a hub, do you want just “ok”???


I also put double butted spokes on mine, although the next size down. No problems for me, subsequently sold to BungeeJoe who undoubtedly rides more difficult terrain than I did, and I haven’t heard of him having problems.

If you want the best and strongest spokes, double butted is the way to go, regardless of size.

P.S. I’ve also received nearly immediate responses from Kris to emails sent to his website, and agree it’s great that he does that.

Interesting conversation.

My partner keeps trying to convince me to use 13g spokes when I build wheel, especially with Schlumpf hubs (they totally fit, I’ve just checked, it’s not tight at all) for customers because our spoke machine is set to cut 13g spokes (we mostly deal with hub motors for electric bikes at our shop, they need 13g spokes). He thinks it’s even doing a favor to our customer since 13g would be stronger.
If i want to use 14g spokes, I need to buy them from another place or have them cut at another place (until we get a second spoke machine)

So far I’ve been reluctant to 13g, not because i don’t believe it would be stronger but because I’m worried it could become more complicated for the customer if one spoke or one nipple breaks… and they want to source it locally. I guess I should just ask the customer if 13g is fine.

I’ll need to build myself a wheel with a geared hub soon and need it to be as strong as possible so I might go for 13g…

Before Sapim renewed their website there was an interesting whitepaper of conclusions of studies, that shown that the hub/spoke/nipple/rim matching is HARD to get perfect.
I’m annoyed that we have better and better unicycles, still see so many people in competition breaking spokes.
But then looking at those cases it usually comes to that above combination.

A strong hub, doesn’t make a strong wheel, if the rest doesn’t match. The same counts for the other parts.
Or when you use that strong hub for different use; example: the Mad4One hub has a VERY small flange diameter, light and so great for trial, but IMHO not that ideal for flatland and freestyle. Also here are 2.9 mm holes, while every rider uses it with 2.0 spokes. But, in comparison to other unicycle hubs these hubs have a very good bedding for the head. Not just a plain hole.

But even when you (like you do here) search for technical details and recommendations, it is very hard to find, even if you go to manufacturers or wholesaler websites. It is ridiculous you have to send countless emails and break trough an entire retail chain to find out nobody seems to knows the ERD of a certain rim (needed to calculate spoke length). And so building a wheel can sometimes take many months.

Anyway, one of the conclusions in above mentioned whitepaper was that (depending on use) a thicker spoke is not always strong than an thinner. I think this is true; but also do think it’s better when it matches the hole as much as possible. And what is more important as the diameter of the spoke, is the length of the head. If it’s to long, they will sit in a weird angle, curved near the head, and adventually break at the head. If the head is too short, you wont be able to get them in.
Also I think, with light but weaker materials you’ll see that thin spokes in too large holes eat themself in.

So in regards to diameter of the spoke, I’d say, take the #13.

In two weeks I will get a Schlumpf unicycle, made by him a while ago. I can let you know what spoke I find on it. I do expect that DT, yes.

I think in general a 2.3 mm spoke would be better than 2.0, but the market doesn’t supply them that easy in the common lengths for unicycles.
But you might want to look into Alpina Raggi spokes to. Originally they use to make motor-cycle spokes. And so they do make thicker spokes than the competition on their market. Hard to get, since retailers can buy each length only in ridiculous amounts. They don’t like putting much money in overstock to be able to supply you only a couple.
But Marco of Mad4One seem to have a good connection with this (also) Italian company now, so you could ask him.