Proceed as follows:
Remove the complete sprocket flange (1) from the wheel.
Clamp the pins (2) at the cush drive rubbers and unscrew the nuts (3) holding the sprocket to the flange.
Remove the flange.
Inspection
The rear sprocket, the primary drive sprocket and the chain must all be changed together.
Check the wear of the primary drive and rear sprocket teeth (1 and 2). If the tooth profile is as shown by the continuous line in the figure, change the sprocket.
To check chain wear, stretch the chain and measure 16 links.
If the length (L) of 16 links is longer than 256.5 mm/10.098 in., change the chain.
To change the primary drive sprocket, see "Removing the primary drive sprocket".
Reassembly
Check that all the pins (2) are securely fixed and tightened to the flange (1). If the pins are loose, unscrew the pins, clean the threads and apply high-strength retaining compound to the large threads.
Fit and tighten the pins to the flange to the specified torque.
Apply medium-strength threadlocker to the threads on the end of the pins (2).
Fit the new sprocket, clamp the pins and tighten the sprocket nuts against the pins to the torque specified.
Warning! Follow the above procedure closely. The pins must be fully tightened before the sprocket is fitted and tightened. If the pins are not fully tightened before the sprocket is fitted, the sprocket will be incorrectly mounted. Loose sprocket pins and an incorrectly mounted sprocket will make the bike dangerous to ride.