Superpedestrian, developer of the Copenhagen Wheel, has raised $4 million in equity funding from lead investor Spark Capital along with General Catalyst. The Copenhagen Wheel is a self-contained unit with a small motor that captures energy through braking or going downhill and provides power assistance during pedaling, multiplying pedal power by 3x-10x. The wheel's app also tracks usage and statistics including distance, time, calories burned and more. Superpedestrian is currently taking pre-orders for the wheel and plans to ship by the end of 2014. In its only other financing round, Superpedestrian received a valuation of $11.4 million in October 2013.