A snowmobile comprises a plurality of ground engaging members, a frame supported by the ground engaging members, and a powertrain assembly supported by the frame. The snowmobile further comprises a rear suspension assembly supported by the frame which includes a plurality of slide rails, at least one linear force element operably coupled to the slide rails, and at least one rear idler wheel operably coupled to the slide rails with a rear shaft. The rear shaft is operably coupled to the slide rails with a single fastener received into one end of the rear shaft.