"With the high power to weight ratio and the centre of mass positioned high over the rear axle this thing does wheelies during acceleration. The wheelie bar at the back works well and the low mass means it is fast, but still safe indoors. The two 16 tooth gears on either side can be changed to a 12 tooth and a 20 tooth to provide either higher top speeds or higher torque. The build is not too long, and is not repetitious, and uses some clever techniques (minifigure paint rollers for mirrors, complex angles used to mount return rollers). I bought this set for the motors, and it has made a strong case for me to leave it assembled."