Here is my thinking on speed components, now this probably is not accurate at all, it's just the feeling I get.
An electric motor without any load pulls very few amps and could run all day at top speed on even a small ah battery. It's when the motor actually does work that it pulls the amps from a battery at an shocking rate.
The wattage of a motor is more about speed under load than top speed. Its about how long a 3000 rpm motor will turn at that or similar rates while under a load. Ie hill climb ect. and the rate that it bleeds speed or bogs down. High the watts the slower it will bog down.
Top end speed will be more about the rpms of the motor and gearing, than about pure watts of the engine.
The reason I think this is the two bikes I have. The hub motor is less watts but has a slightly higher top end. While the pusher has more watts and climbs hills better. The way to increase the speed on the pusher would be to have a motor that ran at higher rpms, use a smaller sprocket on the drive wheel, or use a larger drive wheel.
Any of the above would cause the bike's ability to hill climb to drop. I like the hill climb but wouldn't mind being able to run with local 'in town' traffic.
So in my opinion you need a bike that has high rpm, the right gear combination, and high watts to maintain the power on hills. Higher rpms probably means more battery. I saw a motor on ebay that ran with like 10,000 rpm at 48v... 5000 at 36volts...2500 at 24volts. I assume that brushless wheel hubs act the same...
If I bought a 'cost be darned' hub motor, I would want to compare the rpms not just the watts. They tell me on an ebike forum that there is a good chance I could add more battery with a higher capacity controller. If the same rule applies as to the brushed motor above I could run 36volts and it would double the rpms.
I do NOT planning to do that. I would much rather just wait and pick up a 36V hub motor with higher rpms.
By the bye, there are two used hub motors on ebay today. There is a good chance that they will begin showing up there. If the guy was disappointed in the motor, and I expect most are when they do a cost benefit analysis, it would probably be in good shape. Even if it had a failure, it would most likely be in the controller or throttle rather than the motor itself. Anyway just some random thoughts probably worthless but none the less there they are.
ps if my thinking is wrong feel free to correct me I love to learn new things...
