Yeah, that’s the problem - not even as much room as it looks from the outside as the hub body is higher on the inside. If it wasn’t cut away between the spoke holes it would be an obvious and easy fix.
I’m not sure that you will have a net loss of tension with two spokes pulling on a single hole. It’s true that the force will be somewhat opposed; however not directly. What about building the flange back up with aluminum brazing rod? I’ve never used the stuff but if the infomercials are even half right it may be strong enough. Of course you’d have to strip down the hub, and repack it. Probably a rebuild for the wheel too.
Same thing happened to me, just been riding it. Though about maybe trying some JB weld but I dunnno.
It has been reinforced on the last production and additionnally the radius is now machined on both sides of each holes. My feeling based on the photo is that your wheel has been built with the spoke radius on the wrong side of the hole radius machined on the hub.
I’ve posted this in the STW thread but I though this might be of interest here, too.
If you want a ‘proper’ repair then you could get a new flange laser cut. Basically an annulus with two concentric rings of holes: one set for some m3 bolt to fix into the existing spoke holes and a new set of holes for the spokes. You’ll probably get away with same spokes and it would only cost £10-£20.
Something like this:
You might have to play with the outer hole positions a little to keep the same length spokes, and the inner pattern is just an approximation.
Ah - shouldn’t be surprised to find you on here too! I thought I might get slightly broader technical expertise on STW, but as it turns out the two best suggestions have come from unicyclists.
Not in that photo it’s not - I’d just rebuilt it the right way round (previously one side was wrong)! Though I think where it has broken is on the side where it was always right.
I had the same thing happen to my older generation square taper Schlumpf hub. I sent it back to Florian and he replaced the hub with a new ISIS hub, though this was not free. Hub number 105 was replaced with M501 - their serial numbers pleasingly reversed!
When applieng such one I would skip each time 11 holes until all bolts are tight.
Should probably give an update on my plans for those interested. I like nickjb’s idea as it takes a lot of the stress off the spoke holes, but for now I’m going with something a lot simpler. I mentioned earlier the idea of using a plate bolted to the spoke hole to the left of the broken one with two spokes attached with opposing tension. A slightly more elegant development of that was suggested to me by a chap called Ben from Kinetics cycles (who is himself a unicyclist).
I’m going to get an extra long double ended spoke made up with an s-bend in the middle and threaded at both ends. The s-bend will sit in the intact spoke hole to the left, one end will act as a replacement for the spoke currently in that hole, the other end will replace the spoke which would have gone in the broken spoke hole. I’ve had a good look at the forces involved, and at the worst the force on the spoke hole from this double spoke will be no more than that from a single spoke - provided neither of the spokes ever goes completely slack (as they shouldn’t do in use) the force on the spoke hole will be less than normal.
After searching around for a way to make such a double ended spoke I eventually found an obscure specialist shop which sold something suitable…
It’s a fairly common problem on the earlier hubs. I had a 2008 KH/Schlumpf hub which was hardly used before it broke.
The problem is that the flange holes are directional- if you don’t have the spokes around the right way it puts too much tension on the flange and snaps it.
Mine broke a couple of weeks after a new wheelbuild, and just before my races at Unicon 16. Luckily I managed to buy a new hub and had my wheel rebuilt, but it was still pretty annoying.
Not quite true. My wheel was built with the spoke heads in the flanges the correct way round (the bend of the spoke on the chamfered side of the spoke hole) and it still broke. I think the problem is that there simply isn’t enough material there to allow high tension. This problem has been addressed in the newer version of the hub.
I should give an update on the fix to this - completed this a while ago, but hadn’t got around to taking decent pics.
I sourced a tandem length spoke from who else but UDC - got them to cut it to a generous length and put 20mm of thread on each end so I had a little wiggle room. I then formed a double bend in the middle (not exactly in the middle as one portion of the spoke needed to be longer than the other) using a spare bicycle hub as a former. Was actually pleasantly surprised how well that turned out - did a good job with my first attempt, having ordered 3 long spokes on the assumption it might take several attempts (though I had practiced on some old scrap spokes first).
Here’s the finished spoke:
a closeup of the double bend:
and here it is in the wheel:
you can’t see it? well maybe we need to go closer:
or maybe closer still?
Quite pleased with the way it’s not at all obvious unless you know what you’re looking for.
Great job
Wow. What a great job. Well done.
Hey aracer,
Neat job !
Hubbs is very impressed as well
nobody seems to have noticed yet, but clearly when I said tandem length spoke I meant penny farthing length spoke :o
Really nice thought and processed solution.
Best regards,
Samme
To be fair it wasn’t my idea - first suggested by Ben from Kinetics
http://singletrackworld.com/forum/topic/wheelbuilders-bodgers-help-broken-flange#post-4868054 (I don’t think he’s on here, but he also has a Schlumpf uni).
Ha! aracer 
I did miss that, too busy looking at the pics. 