milesinfront wrote:10in is the OD of the tyre... Current gearing is about 5:1 (11t/56t) I can get a 72t sprocket off the shelf. (large dia sprocket does increase risk of ground contact however) From memory 5krpm at the motor was ~60km/h. I may still need to invent a 2 stage reduction...
what about dropping down a chain size ( if you are running a 8mm ), this will make things a little easier. I would look at running at 12s ( 50v hot ) if you use the 63mm 170kv motor. if you use a 72t rear and a 11t front and the circumference of your wheel is around 800mm this will give you a 50v hot off the charger speed of around 60k . I geared a 24" cycle for around 65k using one of the smaller motors, it was more than capable but did lack a bit of excitement when accelerating hard, but it was only limited to 3kw at the time
this 60k would be the loaded speed, but from my experiences with these motors it will more like 65k anyway, start with the most reduction you can fit then work down.