The dropper post length is dependent on a couple of factors; the first being your saddle height and the second being the maximum seatpost insertion depth which you’ll find listed below. Using the values below and the charts supplied by the dropper post-manufacturer you will be able to figure out which dropper post length is best for you.

Slayer carbon:

Size S = 245mm

Size M = 265mm

Size L = 285mm

Size XL = 305mm

Slayer alloy:

Size S = 240mm

Size M = 270mm

Size L = 272mm

Size XL = mm