New Multi-S Composite-round (Spring + Cellular PU) Rear Two-Way Suspension for Pacific Cycles Birdy Folding Bikes Developed specifically for Pacific Cycle Birdy Performance Folding Bikes Spring+PU design automatically adapts to return spring force Supports up to 230lbs rider weight Weighs only 70g Works best injunction with Multi-S Front Hydraulic Suspensions for Birdy