1.Product quantity: Bearing X 2 pcs, Circlip X1 pcs 2.If your bike is making a “rumbling” noise or is not smooth in the cranks/pedals it could be a bad bearing in either the hub or the belt tension pulley assembly. 3.Belt tension pulleys are for use on Peloton Bike/Bike Plus models only and are not suitable for other finishes. 4.We stand by the quality of our products. If you encounter any problems or have questions, please contact us immediately!