We made these Coaster hubs with attachment for sprocket! Billet aluminum hub with large coaster break inside Check out my video #1 and 2. No more chain jumping due to sprocket twisting under load (original rubber mount)! @Groundbrekr The small sprocket is for the pedal chain and it is the snap ring style. the engine driven sprocket can be bought from www.kingsmotorbikes.com and other "China girl" engine dealers! We sell the hub without the engine sprocket because of customer personal preference but we include the bolts! I hope this helps!