Maximum Rider Weight Figures

[Tubamanandy]

Where do manufacturers max rider weight figures come from or how are they derived ?

Reason I ask is I`m a big guy, 112Kg, yet my current 250W front hub motor (Bafang SWX) is fine. Admittedly, I have to put alot of work in going up hills but I expect that.

Just about to build a new project over winter based on the BPM2 350W just recd from BMS if I can work out how to wire the motor/battery/controller

 

[NZgeek]

I'm down to 120kg now

It's usually more based on the frame design/limitations than on the power figures etc of the motor, from what I've seen. Most traditional cycles will have a frame weight limit too... I'm over a lot of them, but have used them sucessfully (Still have my face and all limbs etc)

 

[trex]

it's usually the battery that limits the ability of your bike. With Samsung cells, you can draw 2C, a little less with NCR Panasonic and Chinese cells. The battery limits how many amps you can send to your motor, that in turn limits how fast you can ride up hills where you live. If you have for example a 10AH bottle battery and a BPM motor, you can only feed the motor with 20A max, you get 720W * 0.78 = 560W at the wheel. If you have a 28A BMS, the same motor can output 800W max at the wheel.
Manufacturers have design goals, if for example they want to specify 6% climbing ability, the target speed is usually 20kph. With a 10AH battery, maximum power = 560W, total bike + riders = 136kgs - it's safe to specify max rider weight 110kgs. Now if they design for hill climbing then 6% gradient is un-realistic, 15AH will be needed.