thats looks like satanix without the spikes.
speed controllers could be an issue.
botbitz should be fine.
if you have something heavy over the wheels that should push the wheels down to the floor.
there are lots of factors to consider.
wheel size
weight and weight balance.
motor positioning.
battery voltage amps and c
speed control.
version of speed 900 motors
things affecting the magnets in the motor.
motor problems.
