The CST Presta Valve (French Valve) is the skinny one that's found mostly on race bikes in the BMX world. Find the right Presta Valve tube for you 20 inch race bike right here at LUXBMX. Choose from short, or long valve lengths (for those deep side walled carbon rims). The shortest 34mm valve will suit most alloy rims, while the 48mm valve will fit any carbon rim with a 30mm depth. For the 20 x 1-1/8 or 20 x 1-3/8 rims with a deep side wall, go for the 60mm valve length.