Patent ID: 6932371

Claim:
A bicycle frame having a rear passive suspension system, comprising: a bicycle frame having a top tube, a seat tube extending downwardly from one end thereof, a bottom bracket shell at the bottom end of said seat tube, a down tube extending angularly upward and forward from said bottom bracket shell, a pair of lower chain stay members extending rearwardly from said bottom bracket shell, and a pair of laterally opposed rear wheel dropout brackets at a rear end of said lower chain stay members; and a pair of laterally opposed upper chain stay members secured at one end to said rear wheel dropout brackets extending angularly upward and forward therefrom and secured to said seat tube a predetermined distance above said bottom bracket shell to stiffen the frame laterally and transfer rear wheel loads to said seat tube; said upper chain stay members secured to said seat tube a distance above said bottom bracket shell at a point to control rear wheel motion predominantly in a vertical direction and, when subjected to rear wheel loads, place said seat tube in bending at or near said bottom bracket shell and allow an amount of elastic deflection of said seat tube sufficient to isolate the rider from road-surface irregularities and roughness, while maintaining rigidity in other directions to improve handling, comfort, and safety.