Your mountain bike is compatible with 31.6 mm dropper seat posts.The cable and housing are routed internally from the top of the down tube and can be easily reached thanks to the Internal Routing Access hatch by the bottom bracket (left-hand side).This video will help you fit your new dropper seat post. Remember that you can also drop off your mountain bike at a Decathlon workshop, where one of our technicians will fit the seat post for you.