The bicycle saddle, or seat, is made of leather, vinyl, plastic, or gel-filled material (for extra padding) and is wrapped around a metal frame bolted to the seat post. In general, a very wide saddle is less desirable than a narrower one, because it is heavier and may interfere with the movement of the thighs while pedaling. The narrowest saddles are usually preferred by male riders. Some manufacturers have designed saddles to accommodate the wider pelvic structure of female cyclists.
Saddles have also been designed with cutouts in the hard base material and grooves down the center to relieve pressure on pelvic nerves and the pelvic “sit bones.” To fit a cyclist, the height of the saddle can be adjusted by 15 cm (6 in) or more by raising or lowering the seat post in the bicycle frame’s seat tube. For further accommodation of fit, the saddle also may be slid a few centimeters forward or back on two parallel rails welded to its frame. A joint where the seat post bolts onto the saddle allows the saddle’s nose to be slightly tilted up or down.