Try to build my first ebike

[patpatbut]

Sorry I have been searching around I could not find out the definite answer.

Have anyone done the comparison?

Thanks

 

[morphix]

Thanks guy. To be honest, I still want to build a legal bike 36v 250w.

I wish I could make it running steady 20mph as well for off road purpose.

How about this rear motor

36V QSWXH Rear Drive Brushless Hub Motor - BMSBATTERY

Would it be able to run 20mph with 20amp at 36v?

Will I get a lot of voltage sag using 36v 12ah lifepo4 battery? If not, I would have to 48v with lower amp right?

Pat

Hi Pat,

I built my first bike 2 years ago and used a 26" MTB bike and a 250W front hub 36V kit I bought from rftec.eu in Austria. Although the kit was more expensive (330 euros) than buying one from BMSBattery or GreenBikeKit, I believe it's a better kit, it also has an LCD console. I added to this a 36V 10Ah battery from BMSBattery. Even without any modifications I'm able to do 20-22mph on the flat on my bike with full power and pedalling not very hard.

For me the key to getting speed is to keep the bike highly geared and I have my bike in 6th gear permanently. So when I pedal there is maximum torque/speed. It's even necessary to have it so highly geared for me just to keep up with the motor when its running at full power else I'm free wheeling.

The controller I have is road legal and restricted to 15.5mph but I can still manage to get that speed over 20mph easily. I think a key thing to consider too is the weight of the bike, rider weight, and having good tyres with the right pressure. My bike weighs about 20kg in total with the kit and I put Marathan Plus road tyres (slicks) on.

I can get about 40 miles range (estimate) from 36V 10Ah at full power with pedalling. I initially tested a 36V 5Ah battery and that gave me 18 miles at full power with pedalling. 10Ah battery is the minimum I would say for 36V motor if you want good hill climbing as the motor needs more current than a smaller battery can provide and the battery will get stressed.