Bastard Midget Spokes

Have you done this before?

Yes, done a 3x and a 3forward/3back, no drama.

But I think I've worked it out!! It's to do with the way I put the spokes on, the order of spoke groups (and of course the fact that the spokes are too short).

I lace the spokes with leading spokes running up the inside of the flange, so they don't get caught when the chain comes off during a skid, etc.

I'm careful to be consistent with this on a flip-flop hub, so the first group of spokes I put on are trailing spokes, equivalent to "trailing cassette-side" spokes on a normal wheel. Spokes outside the flange.

While the second group of spokes I put on would be the "trailing non-cassette" side on a normal wheel, in my case they're actually leading spokes on the flop side, so they get spokes inside the flange.

All the spokes outside on the one side, all the spokes inside on the other.

This fucks up my dishing, so when I put on the "leading cassette-side / flip-side" spokes I end up with a wheel almost dished flat, and can't get the last group of spokes on (what would have been "leading non-cassette-side", now trailing on the flop side of the hub. That's why the spokes wouldn't go on, even though they're only 2mm too short.

Have I explained that in a way that makes sense?

Basically if you're using the Sheldon technique to build up a flip-flop hub and you're anal about spokes in/spokes out, you should put on the first group of spokes, then the third, then the second, then the fourth.