speedyebikenoob
1 kW
- Joined
- Feb 6, 2019
- Messages
- 333
So I've been working on a tachometer for my e bike which is powered by a middrive mini cyclone motor. Before I did that though I just wanted to figure out what the maximum rpm of the motor actually is. It has a 13 tooth sprocket on the motor and the chainring it connects to is a 44 tooth. At the crankset in the front, I stuck a piece of orange tape on it and every time the tape passed a marked point on the bicycle frame I counted it as one revolution (used the slow motion feature on my phone to accurately count). After one minute, I got 268 rpm on the front sprocket. I calculated the ratio between the motor sprocket and the chainring and figured out the 13 tooth motor sprocket is turning at 907 rpm. Because the motor has a 9.55:1 gearing ratio, this means the motor is spinning at nearly 8700 rpm. Uh what? I thought the max for these motors was about 5000? Am I just doing the math wrong somehow or is that how fast this motor spins? This was through a 60 volt battery and the stock controller by the way. If someone who has a cyclone motor could clarify this for me it would be great, does your motor also rev that high?