Mon, Tue, Thur, Fri (Noon - 6pm) & Sat (9am - 1pm). Closed on Wed & Sun.
Shimano Dura-Ace triathlon chainrings are designed to be used only as a set 42/54, 42/55, or 44/56. 45t ring is an option to be used with the 56t ring (any other combinations may result in poor shifting).