Constant tension, internal friction, dirt and rust lengthen the bicycle chain by several tenths of a millimetre. In the process, it also gradually wears out the spaces between the sprockets and chainrings. A new chain no longer fits exactly into the teeth: it jumps when shifting gears. Depending on the load and maintenance condition, a sprocket change is necessary approximately every three chain change intervals. When buying a new cassette, make sure it has the right number and gradation.
Remove 1 axle
Remove your rear wheel and take out the axle. The toothed locking ring must be freely accessible.
2 Set the gauge
Not all sprockets wear out at the same time. The most frequently used ones are hit first. With the HG-IG-Check wear gauge from Rohloff, the wear on Shimano and compatible sprockets can be measured precisely. Place the measuring chain of the tool with the end link folded up on one of the most worn sprockets.
3 Measure wear
Apply tension to the electrode by pressing on the lever. Then fold the end link downwards. If it cannot be placed in the gap without resistance or if it stands up on the tooth, the chain is no longer running smoothly. The sprocket is worn, the cassette must be removed.
4 Open the locking ring
Insert the Shimano TL-LR15 nut into the serrated recesses of the lock ring on the freehub of the wheel. Use a spanner with a long lever for the nut.
5 Counterhold pinion
The locking ring is opened in a clockwise direction. However, this is where the cassette turns empty on the freewheel. You must therefore use a chain whip to counteract this. Place the chain on one of the larger sprockets and grip the whip handle with one hand together with a pair of spokes. Then turn the spanner and nut away from the whip with the other hand. The lock ring is also grained on the inside and rubs a little when you unscrew it.
6 Remove pinion
You can now remove the sprockets from the freehub body. On a 10-speed cassette from Shimano, the sprockets are divided up like this: The smallest three sprockets are fitted individually and are each fitted with a spacer collar. Sprocket 4 is flat, followed by a single spacer ring. Sprockets 5 - 7 and 8 - 10 are each mounted in groups on a spider.
7 Clean pinion seat
Wipe all old dirt from the ribs and gaps of the freewheel body.
8 Grease protects
Grease the mounting surface well before assembly. This prevents the cassette from seizing even after a long period of time.
9 Note interlocking
The sprocket and spider, like the freewheel body on the outside, are provided with ribs that transmit the drive force to the hub. However, one gap is wider than the others. This means that all sprockets are in a defined position in relation to each other and the embossed gear grooves can transport the chain optimally.
10 Align spider
Slide the spiders of the first two sprocket groups onto the freewheel body. Align the spiders with the widest recess in the ribs and push them all the way onto the fit.
11 Individual assembly
Then fit the individual sprockets so that their labelling and the gear track always point towards you. Do not forget the spacer ring between sprocket numbers 3 and 4.
12 Attach the locking ring
Insert the locking ring into the internal thread of the freewheel body without tilting it.
13 Screw in carefully
First turn the ring with the nut slightly in the opposite direction to make it easier to find the start of the thread. Then screw it in hand-tight.
14 Tightening
Finally, use the spanner to finally tighten the lock ring against the direction of freewheel rotation. The grained surfaces at the contact points of the end pinion and locking ring rub when tightening. This roughening prevents this screw connection from loosening automatically.
You can then insert the quick-release axle and remount the rear wheel in the frame.
