dogman wrote:So it's definitely a compromise. It's good within a certain envelope, and bad out side the limits. It works good for me for riding on dry pavement, or wet that is not too steep. It's no good for dirt riding, trail riding. You just gotta have a rear hub for that. Dual hub can be nice in dirt, but really I prefer to have a light front so I can pull a small wheelie over larger obstacles. I run 1200w max, 48v. So I burn a little bit of front tire rubber, but nothing that alarms me. You should get quickly used to a small wheel spin the first foot or so as you start. Do be cautious about going from 0 throttle to full on a corner with wet or sand. But if you are already spun up, you can power through a corner fine.
Ok, it's decided. I will go with the Bafang BPM 500W front motor on aluminum forks but using 2 arm torques.
My travel is 50km (25km + 25km to return) on flat dry pavement/tarmac roads (I live near the ocean). 2 years ago I did this with 180W front motor, 1 year after with 250W front motor and now I want to go with the Bafang 500W.
My controller gives 22A at 48V, which is 1056W at start. Since I came from a 250W motor and I just need more 50 or 100W, I will do 2 things:
- limit the maximum throttle with a circuit to 0.7, 500W*.7 = 350W
- ramp up the acceleration of throttle with the opamp circuit(or Arduino) to have 3 seconds of ramp from 0 to maximum power
Limiting the power to 350W to be safe, also because I don't have gears to go over 44km/h (maximum speed with the 250W motor were 38km/h) and I want to always pedal, also I will ride 50km with a charge but I plan to increase for the 70km/h.
I wish I could limit the power and ramp up on the controller, so when lifting to the air the wheel like on a bump, the wheel would take time to accelerate and so more safe.
I hope to survive to any possible accident due to front motor and have the chance to change for rear motor
My actual electric bicycle is this one (V2.1 in Portuguese):
It is a Cute-85 motor for 16'' but installed on a 26'' wheel, 250W, 24V. Battery 24V 25Ah.