Schwinn Sierra 1 Women's Bike. The Schwinn Sierra 1 women's bike is all about ensuring your rides are incredibly comfortable, enjoyable endeavors. Its aluminum frame featuring a women's specific step thru design is lightweight, ready for all weather riding, and provides a lively, responsive ride that only aluminum can deliver. Up front, there's a SR Suntour M3010 suspension fork providing 63mm of bump absorbing travel. Combined with the suspension seatpost and a plush gel saddle, the Sierra 1 ensures each and every ride is smooth as silk. Shifting through the bike's 21 speeds is a breeze with the SRAM MRX Grip Shifts and Shimano derailleurs while Promax V brakes deliver dependable stopping power.