A difficult question to answer. The length of dropper will depend on how much drop you need and how much post can fit inside the seat post tube without fouling on the pivot bolt. Bike Yoke Dropper posts have a shorter lower tube than most other brands and also come in 125mm,160mm and 185mm drops. Xfusion do a 150mm drop but the lower post is longer than a 160mm Bike Yoke.