20" rear motor for kids ebike.

[Trevormonty]

Friend wants to fit kit to 20" kids bike. Any advice or recommendations on following would be appreciated.

After light rear 250w 36v motor or better wheel.
Low weight is more important than power as kid is light plus torque advantage of 20" wheel. Needs to handle Shimano 10spd cassette.

Also need controller that can be program for consist current/power output. Plan is to have 3-4 power settings. A handle bar switch with Up Down.
Cutoff for hydraulic brakes.

Plan to use a couple of 18V drill batteries, being builder has few spares. A couple 3A should keep weight down.

 

[sjpt]

Don't forget eBikes are only legal for children of 14 or over.

 

[wheeliepete]

BMS Battery do this small motor that will take a cassette. More than enough power for a kids build. Only 2.1 kg. Go for the high speed (328 rpm) to suit a 20" wheel. Rated at 350 watt, but it's only written on a sticker, which falls off very easily

https://bmsbattery.com/ebike-kit/618-q100c-cst-36v350w-rear-driving-ebike-hub-motor-ebike-kit.html

This controller can be power/speed limited from the LCD.

https://bmsbattery.com/controller/827-s-ku65-250w15a-6mosfets-controller-without-led810.html

https://bmsbattery.com/parts/670-s-lcd3-lcd-meter-for-s-series-controlers-ebike-kit.html

PAS sensor and throttle in parts section.

 

[Trevormonty]

BMS Battery do this small motor that will take a cassette. More than enough power for a kids build. Only 2.1 kg. Go for the high speed (328 rpm) to suit a 20" wheel. Rated at 350 watt, but it's only written on a sticker, which falls off very easily

https://bmsbattery.com/ebike-kit/618-q100c-cst-36v350w-rear-driving-ebike-hub-motor-ebike-kit.html

This controller can be power/speed limited from the LCD.

https://bmsbattery.com/controller/827-s-ku65-250w15a-6mosfets-controller-without-led810.html

https://bmsbattery.com/parts/670-s-lcd3-lcd-meter-for-s-series-controlers-ebike-kit.html

PAS sensor and throttle in parts section.

Thanks Wheeliepete.

As for being legal, we are in NZ so not sure of law regarding kids and ebikes. Need to investigate that.

 

[awol]

If your friend can get a motor laced into a rim the Xiongda YTW-06 is a good one. I am currently putting one onto my sons bike now he's old enough. It can be purchased direct from Xiongda. The Lishui controller which I got with it is an 11a one.

http://www.pedelecs.co.uk/forum/threads/new-tiny-xiongda-motor.27981/

http://www.pedelecs.co.uk/forum/threads/small-rear-xiongda-motor.28353/

Search the forum for Xiongda for various threads using one.

 

[wheeliepete]

I thought the Xiongda would be a good choice too, but OP wanted a hub to take a 10 speed cassette, although I'm not certain 10 speed would fit a kids bike frame.

 

[awol]

I thought the Xiongda would be a good choice too, but OP wanted a hub to take a 10 speed cassette, although I'm not certain 10 speed would fit a kids bike frame.

I missed the 10spd cassette requirement, your Q100C 328rpm is probably a more suitable option for that.

 

[Trevormonty]

I missed the 10spd cassette requirement, your Q100C 328rpm is probably a more suitable option for that.

Plan was to use on Norco FS 20" and 24" bikes.