The styling of a bike jersey is developed for a forward, leaned over position. You will see that the back is longer in length than the front. The arms are cut out in the arms-eye for the forward position of the arms as they reach for the handlebars. The neckline is often cut very deep for the forward position of the head on the bicycle. Zippers add to the neckline comfort. Most jerseys have at least a partial zipper to open up the chest to vent heat between climbs. Three back pockets that are easy to reach with one hand and set up higher on the small of the back so you can carry something heavy like a full water bottle without snagging the seat when standing. Bike Jersey fabric is a wicking polyester or micro-mesh that is technically designed to wick body moisture to the surface for evaporation resulting in a cooling effect in summer. In the winter, the wicking fabrics create a dry layer next to the skin.