I am going 50 km/h on a 200W rear geared hub, 12S Lipo, folding bike with rear suspension, the motor does'nt get hot, only slightlly worm, I tried putting the controller inside the battery bag, but it got really hot after a hard ride (a 450W 9 FET controller from bmsbattery, 22A limited), so I moved to a 12 FEt controller and put it outside the bag, the motor still handles the 30A without getting hot.