It all depends.
What do you already have?
If starting from scratch then you figure out the terrain you will be riding, how steep the hills are, how fast you want to go.
You could buy a 2T or 3T motor
- Have the hub motor laced into a 18" or 20" bmx bicycle rim to get extra torque out of it due to the gearing (diameter of wheel, smaller = more torque less speed, larger = more speed less torque easier to overheat.)
- Then you figure out the battery and controller.
You could go 96V, you could go 78V, 60V, 52V, 48V, 36V
Then you need to figure out what battery you want, buy from a known reputable entity, throw the dice on some back alley mystery gamble (ebay/amazon/alibaba/aliexpress), or build it yourself.
What amp discharge you want for the batteries BMS
Then you match the battery to the controller, do you want programmable controller, do you want Bluetooth, do you want Sinewave, FOC, Field Weakening or any other specific controller feature or do you want to cheap out and buy a generic trapezoidal controller with little features.
Of course you can select your route and do a trip sim
https://ebikes.ca/tools/trip-simulator.html
or motor sim
https://ebikes.ca/tools/simulator.html
To really dial in your numbers.
alexscard said:
But.. 7*9 shouldnt be considered fast wind, isnt It?
I'm wondering, if someone wants a motor that has an High Speed(lets Say from 40mph on) but that can also make uphill without overheating, what motor should buy?