Bionx electric assist. I got this used and would like to sell the electric assist off of it. The wheel rim is a 700. Included: two batteries, charger, and rear wheel motor. It is still attached to the trike, and I will remove when sold. This unit can be used on any bike. It attaches to the water bottle attachment. In Coralville. Call or text. Reduced to $300 for the assist or $2,200 for the CATRIKE Dumont foldable trike.