Well, I couldn't sleep last night so I went through my other odd bike wheels I had lying around.
The wheel I had made up wasn't quite working out. The spokes were a little long and though I got the three cross I didn't have enough thread left to true it. So I found another wheel to strip apart that gave me an intermediate spoke length.
At 3.30am I built a wheel for Emily that works and trues up nicely. The wheel is fitted now but I am having problems with the sprocket not working with the chain.
The chain fits but when the cranks are turned it looks like the pitch is different! The chain engages two teeth and then rides up the next few teeth then settles down again for a couple of teeth. It looks like either the chain length has shrunk

or the teeth on the sprocket are too long to allow the chain rollers to fall between them.

Maybe the more likely problem is the chain is too narrow for the sprocket, though the sprocket is a 3/32 as it is thinner then the 1/8 I also have. The sprocket on its own rolls nicely along the chain when it is straight.
