What do you think about this idea?
With this setup and 14,2v battery (and no load) the wheel spin with 26,2 km/h (bike computer read).
Motor: ROXXY 5055/45 : 8 ... 30 V, 9A-20A (60s), 100 rpm/V (no load), 85 rpm/V (with load), max 600 W, 6 mm shaft, 290 g.
P.S.: how can I atach a movie?!