Abstract: A bicycle frame using in combination with tubing elements a main channel frame member. The main load carrying member of the frame is an inverted "U" shaped section, or channel section which is tapered in both the horizontal plane and the vertical plane from the front of the bicycle frame to the rear of the bicycle frame (depth and width of the frame member increases from the front to the rear). A head tube is joined to the front of the channel frame, a seat mast tube runs through the middle portion of the channel frame member, and is anchored to the web of the channel frame, and a down tube extends from the top part of the head tube through the web of the channel section between the head tube and the seat mast tube to the lower portion of the seat mast tube where it is affixed to the seat mast tube, or to the bottom bracket. Optionally, further diagonal bracing elements can extend from the top of the seat mast tube to the back of the frame to connect to the channel frame member at either side of a rear wheel.