A suspension system for a bicycle comprising a rear wheel mounting member (4), a chassis member (2), an upper linkage (6) pivotally connected to the rear wheel mounting member and the chassis member at first (P1) and second (P2) pivot points respectively and a lower linkage (8) pivotally connected to the rear wheel mounting member and the chassis member at third (P3) and fourth (P4) pivot points respectively thereby forming a four-bar linkage system, characterised in that the length of the upper linkage (6) between the first and second pivot point and the length of the lower linkage (8) between the third and fourth pivot points are both are greater than the separation between the second and fourth pivot points. An embodiment includes a jockey wheel or idler pulley which provides a tensioned portion of chain which passes through the instant centre of rotation (IC).