Miles,
I have a TSR myself, also grey but with caliper brakes. I'm wondering is you have described somewhere how you built the rear pulley? I know it's made from a Strida 'chainwheel' but I'm wondering how you designed and built the freewheel, especially given that it seems to fit onto the rear hub driver mechanism? Have you a drawing perhaps?
I'm also interested to know if you are aware of a more commonly available motor that would function similarly to the Planet Rider you used?
Thanks,
Savvas.