ISM Saddle PS1.1 BlackFeatures ISM seats are bike seats where you really sit on. The ISM race bike saddles are flat, most of the other saddles are convex. Because this bike saddle is flatter is the place where your sacrum is on the saddle really comfortable. The upper side off the bike saddle is cm lower than then other bike saddles. The race bike saddles has some extra because this seat is in fact noseless, but the saddle has to follow the rules of the UCI and the US.