I managed to improve power transmission by using sprockets with already added hubs. I just had to make two threaded holes in hubs and modify motors’ shafts to make flat surfaces on them.
Another thing that I did is motors’ temperatures monitoring – I had some concerns about motors’ overheating so I added LM35 thermometer to each motor and quickly built board with 2×16 LCD, ATmega328P (on Arduino Pro Mini clone board) and a 7805 voltage regulator.
I also rerouted the wires a bit since they were quite messy (they still are, but slightly less 😉 ).
Tests showed that my mechanical solution works OK – no sprocket slip on motor’s shaft. Temperature monitor also passed the test – I noticed that both motors have the same temperature (+/- 2 C) – I was worried that one motor may get hotter than the other because I changed bearings in one of them. While riding, motor’s temperature is about 6-10C higher than ambient temperature. When I stop and no airflow occurs motor temperature is higher, around 15C. No big deal here.
A few more photos of the board:
Right now I focus my efforts on building case for batteries and designing electronics (power – IGBTs, sensing (temperatures, currents, voltages) and displaying data). I encountered problems with 128×64 graphical LCD I took out of HMI control panel – I believe it’s some kind of wiring error (I don’t know which type of pinout it has).