ProConnect sprocket change
Tom, have a look at the link below to a thread with advice from Aldby and myself on the sprocket change for the Nexus 7. The job is similar for the 8 speed:
Sprocket change
The next link below is to the technical document for the Nexus 8 for the cable adjustment afterwards:
Nexus 8 PDF
.
Print off the thread with advice from Aldby and Flecc.
The Shimano rear wheel (WH-8R25) uses a Shimano Nexus 8 hub and a cassette arrangement (CJ-8S20), into which the gear change cable is clipped.
Before starting a sprocket change, it is useful to take a couple of photos of the arrangement to refer to later if memory is lost.
From Aldby's post (edited for ProConnect):
To remove the rear wheel on the ProConnect:
1. Select 1st gear, this releases tension on the gear cable.
2. You should now be able to pull the outer cable forwards by a few millimetres where it locates into the cassette holder.
3. The inner gear cable will now be free of tension and can be easily detached from the gear hub.
Column 3 in
Nexus 8 PDF describes this well. It helps greatly to get a little extra slack using a thin 2mm Allen key or old spoke placed in the hole on the outside of the cassette pulley, as described at the foot of the column. Do
NOT disturb the inner cable fixing bolt.
4. Slacken off the rear V brakes completely so that the wheel and tyre are freely removable.
Turn bike upside down.
5. Slacken off the hub nuts enough to be able to remove the wheel from the dropouts.
6. You should now be able to lift the the wheel out and remove the chain from the rear sprocket at the same time, leaving the chain still as a continuous loop on the bike.
Lay wheel flat on a bench (or across your knees). Place each item that you remove carefully in the same orientation ready to go back.
7. Remove the cassette that held the gear cable by rotating the centre fixing ring (yellow dot) 45deg anticlockwise. Lift off the cassette.
8. With flat bladed screwdriver, gently ease up the plastic ring (driver cap) that covers the "snap ring" which holds the sprocket in place.
9. With the screw driver, gently prize the snap ring clear of the sprocket, taking care as it will fly across the room very easily. Lift off the sprocket.
Assembly is the reverse and is escribed and shown in Nexus 8 -
Sprocket and Cassette PDF.
Sprocket
SnapRing
Driver Cap (plastic ring)
Cassette (align red dots)
Cassette Fixing ring (align yellow dots and twist 45 deg clockwise)
Wheel is now ready, but shorten chain before refitting in frame as per earlier post.
Remove 1 chainlink (= 1 inner + 2 outers) and rejoin with 1 outer.
Check chain is
correctly routed through the panasonic drive.
Refit wheel into frame, checking chain tension as the wheel is pressed into drop outs. Check wheel is aligned and central in the frame.
Make sure the wheel nuts are well tightened to prevent wheel shifting when pedalling hard.
Still with gear selector in 1st gear, rehook the gear cable as described
here at the foot of column 5.
Gently test that pedals turn, and chain passes freely around circuit.
Set bike upright.
Select 4th gear to check that yellow marks are still aligned.
Reconnect brakes.
Double check wheel nuts.
Gently test that everything turns smoothly.
Comments from other members very welcome.
James
