I use "thingie" in the title to not give anyone a false impression of what I do or don't know.
I'm working with a client who's using one of these in his specialized bike:
He's currently using the 250W version, but we're having problems of insufficient torque -- this is partially due to re-purposing a board, and we're on top of that part, but I'm thinking ahead (well, borrowing trouble, in proper engineering fashion). So we thought -- hey! We'll use the 350W version (that's the one in the link).
The problem is that the 350W version actually has a lower current-to- torque constant -- it gets its higher power through pulling more current for the torque, and delivering more speed.
So -- any thoughts on an easy way to gear the thing down? I just recommended to the customer that they put two chain rings on the crank, so that they can drive the pedals at one speed and the bike at another.