Hello p4p4gaio,
in your first question you’re also answering yourself, guess you just overlooked the basic issue:
If you are able to find a single side mounted motor you could (maybe!) mount it on the Strida single side axle.
I’m writing maybe because you will have, even if you could find a suitable size, still the problem of the motor cables!
(There is no cable hole in the Strida frame - please don’t think of drilling one…)
You’re right, the Strida bottom bracket is unusual, I mean the BBS01/02 mounts will not fit, they’re intended for standard brackets.
Moreover that you must keep the function of the Strida excentric bottom bracket for belt tensioning; I’m quite unsure if this function would still work work with that type of motor mount.
Yes, it’s possible to use a (more or less) common freewheel and chain on Strida
- for example the forum search (upper right corner) will show 133 results for “chain”