How to tell if your controller outputs enough amps to hit your motors full "peak watt output" - Horsepower.
You will need:
Speedometer & watt meter
Typically, a brushless hub motor hits maximum watt output at near 40% of no load speed.
Well, 1st you need to determine top no load speed.
Place speedometer on motor wheel.
Raise wheel and run at full throttle.
Observe top speed.
Peak motor output occurs at near 40% of no load speed (12mph if 30mph no load speed)
On road ...
Observing watt meter carefully, give full throttle.
Watts will stay the same till a decrease occurs.
This decrease occurs at the point where the motor accepts less watts than the controller can put out.
Repeat test, staying closer to this transition point, trying to pinpoint exact location, speed wise.
If this transition point is below the 40% of no load, then your controller is capable of full peak watt output - horsepower!
If higher, then you probably would benefit from a more powerful controller.
See - Determing Horsepower - Output Watts ... Simple Method!