These shimano m324 spd mountain bike pedals combine the efficient spd system with the classic pedal design to deliver truly all purpose pedals spd stands for shimano pedalling dynamics an integrated pedal and shoe system that provides more power to the pedal with the ability to walk safely and comfortably when you39re off the bike what spd actually does is to stabilise the foot and distribute pedal force more evenly to make pedalling more efficient perfect for a wide range of situat