That's great advice. A lot of people don't really understand gearing and motor loads so I just wanted to put something really clear out there. The higher the motor speed, the lower the amps, and big amps/low speeds are tough on stuff for sure.
@MacRibs
About the wheelie, even when geared for 56, my old 3220 bike would spit right from under a 240 lb baja racer if the throttle got pegged but it would still get way too hot on long hill climbs. A wheelie takes a short burst of high current, which the parts can usually handle. A steep hill loads everything up similarly for a longer period of time and the small components can't shed heat fast enough. Bigger motors and controllers take longer to saturate due to mass but still have the same issue. That's why the Bultaco e-bike isn't out yet. They went with a hubbie for a trail bike and it can't handle hills. I offered to give them a design for a sick mid drive bike for free, just too see it get built, but I guess they weren't interested. I've kept quiet about it for months now but the kickstarter folks deserve to know what the hold up is. Hills either need the right gears or mass, forced cooling, and big amps. Put knobbies and suspension on a bike, and someone's going to try riding it up nasty hills..lol A lot of guys here think motor design can replace gearing but unless someone builds a dual diameter stator motor that uses a lot of poles and large diameter stator for low speed, then switches to the smaller diameter stator with fewer poles(due to controller e-rpm limits) for high speeds, off road bikes that can climb slowly and also go fast need gearing options. Usually two or three speeds is plenty with 8kw on tap so 6 speeds with 3kw and a similar speed range sounds perfect.
When geared down to 42, I got a 1.6 second peak of 666 amps out of my poor little hv160 despite all of the current limiting, going from 3mph to 42 in just a fraction of a second longer than the peak, balancing between kissing the front tire and flipping over backwards, but a sustained steep slow hillclimb at 160 amps would sure heat things up. At first, gearing it down made it violent, but I can't express how much more controllable the bike became when I figured out the perfect CA settings. The coolest revelation was setting the throttle voltage threshold slightly below resting throttle voltage and setting it up so the throttle wouldn't work under 3mph. This keeps the motor spinning all the time, even when off the throttle, only pulling 1 amp and easily over-rideable by the brakes and it kept the slack out of the chain which prevented the surge feeling when first hitting the throttle.
ICE dirt bikes are similar. For crazy wheelies, I'd usually start in second gear on my old XR660R because there was enough juice to get it up there and enough speed to keep it up for long enough to get settled enough to upshift. If I started on a steep hill in 2nd, it was either slip the clutch a ton until it got going, or stall out.
. 
