Dual Drive is a single-sided shifting system that is actually fun to use No longer do you need to be a guru in ways of the shifter in order to find a smooth ride You can quickly thumb your way through three easily identifiable riding modes, then click up or down the twist shifter to find your comfort level DUALDRIVE FEATURES: For use with 24 or 27 speed Shiftable under load or while stationary Transmission range: 578% (27 speed), 541% (24 speed) Can be used with one handed dualdrive shifter or dualdrive trigger shifters Freewheel, disc & i-brake versions available Weight: 970g (freewheel version)