Suspension + Drop. The Coast Post combines the benefits of a dropper with the joint saving squish of suspension. This witchcraft all happens via a dual chamber hydraulic cartridge featuring 40mm of tunable air suspension, designed to help riders on all types of bikes - from packed up trekkers, to the cross country wanderers, even the weekday commuters. TUNABLE AIR SUSPENSION. With 40mm of tunable air suspension integrated into the Coast dropper post, your gravel or XC ride just got a lot smoother. EXTERNAL & INTERNAL OPTIONS. The Coast dropper is available in both internal and external routing options, both keeping your cables out of the way.