rojitor wrote:Yes 1440w your maths are right. I pedal only at low speeds, in the middle of the traffic i pedal all the time and between towns i go fast so i don't pedal at all.
Thank you for your info. I guess you don't pedal when you go fast because you don't have gear for that velocity, which is something I don't like to do. I want to exercise myself, it's good for my healthy. Because of that, I think I will need to go with front wheel motor since the rear motor only have gears of 14T instead of cassette type which have 11T (as my current setup).
About the 1440W, 30A at 48V, I think that I will buy and use a KU63 controller which powers the motor at 48V*20A = 960W at start.
d8veh wrote:I wouldn't take too much notice of that 30A written on the controller. The only way to be sure is with a meter. I had a KU123 that gave 40amps and a 25A controller that only gave 14A.
Your main problem is that the motor gives maximum torque at low speed, which makes it difficult to control. Look at some of the threads about smoothing the throttle.
Yes, I was thinking in used a resistor divisor (only 2 resistors) to limit the maximum throttle/possible motor power. I came from a 250W motor and I just want a bit more power, maybe more 50 or 100W (mainly for days with wind) and a bit more velocity (~6km/h). 500W seems a lot to me and also I want to travel 68km with a battery(s) charge.
So yes, I think having a "soft start" would help me on safety and avoid strong torque forces on dropouts. Let's see if changing from KU123 to KU63 will also help me on that.
I am reading this
threads about throttle control (I see a cheap Arduino/AVR board being used for that
Haste wrote:casainho, what kind of battery are you using with the bpm?
48V 10Ah Li-Ion Alloy Shell EBike Battery Pack.Front VS Rear motor
I wanted to go and try a rear motor mainly because seems to be more safe to me however I see 2 main problems on using rear motor:
- I loose speed on the gears because of the 14T freewheel (now I have 11T cassette and I get about 40km/h while pedaling)
- maybe I would get wheelies and loose traction on front wheel due to bad weight distribution as explained here:
Assuming the battery is located at the rear of the bike, you get a better weight distribution (as opposed to a typical front wheel drive).
Also, practically you get a two wheel drive (rear wheel pedaling and front wheel motor assistance). A two wheel drive is better for use on slippery surface because you get better handling (Just like a four wheel drive automobile). Another thing is that the front wheel motor assistance won't cause any unintended wheelies on sudden acceleration.