The motor was made in a small batch only, a few years ago. It never went into production, I'm afraid.
The 16t 8M motor pulley was a custom job, the smallest commercially available is 22t and the smallest recommended size is 18t, but it works fine..
The 100t rear pulley is from the crankset of the Strida 5 bicycle - you can buy the whole crankset as a spare part.
16t to 100t is only 6.25:1, though...
To get a greater reduction ratio, in a single leap, you have to move to 5M size belt, but this means a completely custom large pulley.... 5M pulleys are available down to 12t but 16t is probably the smallest of any use in a one step drive.
Probably a good compromise between torque transfer, reduction ratio and size would be to use 18t to 180t 5M (10:1)
An alternative for less powerful drives might be to use a 100t belt as a tyre on the Strida pulley and run it as a toothless pulley with a 5M belt. This would give 18t to approx 162t (9:1). I've only tested this on the workbench so far, though....
So, there are various possibilities in terms of pulleys.
It would be fun to put together a kit of parts if there was some kind of concensus as to what people want....