For the installing of XDR freehub body on rim brake hub two pieces 5mm and one 6mm Allen keys are necessary. To loosen the shaft's end caps, use a 5mm Allen key on each part of the hub and twist the non-drive side to the left. Loosening of the end caps can also be done by the hands. Insert the 6mm Allen key into the axle and grip it side, while rotating the 5mm Allen key to loosen the end cap on the drive side. Freehub body with its internals are to be pulled off the shaft. In the top recess of belly put spacer barrel, leaf spring and ratchet ring into XDR freehub body. Place the double lip end cap over the drive side and rotate it till it fits. Place the single lip cap of end over the non drive side and fit the drive side end cap back.