Quote:
Originally Posted by puddleglum
govman, nice job. It looks like your motor is driving the crank through a freewheel, right? How do you keep your motor from overspeeding your crank at full throttle? Unless you have a really low speed motor, the gearing doesn't seem low enough. Am I missing something?
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Yes, I believe you are missing something. If you look at the close up of the motor/drive sprocket, you will see the crank is attached to a freewheel bearing. When the motor turns (clockwise) it only drives the sprocket and not the crank. This in turn, turns the stock sprockets which turns the chain as if you were pedaling but the pedals do not turn. If you do pedal, the freewheel locks and the crank powers the stock sprocket or if you apply power and pedal, the motor will provide assist. It is truly a hybrid w/ 3 possible power sources (the motor only, pedal only or motor and pedal).
As for the gearing, I can change that to match the terrain just like on a regular bike. The front sprockets are 48/38/28tth and the rear is a 14-34 tth 7 speed rear freewheel cassette.
All this makes for an excellent ebike that is suitable for riding over various terrains. This is really just my proof of concept bike. I am experimenting with various gear ratios to see which one best suites my performance desires. So far I have migrated from a 11-28t rear cassette to a 14-34. The 14-34 is better for all electric riding and I still have high enough gears for normal city riding. My next mod will be switching the front triple spocket to a 24/34/42 setup for even more low end torque. This should allow for better hill climbing capability and faster takeoffs and still allow for full speed operation.