Sprockets and chainrings.
In order to ensure that the chain can swich from sprockets flexible , are chain sprockets for indexed switching systems provided with special profile. See fig. 35 and Fig. 36. Derailleur systems without index swiching the chain had to be something beyond a sprocket to change from sprocket. Subsequently, the derailleur could be put right under the sprocket wheel. With the index derailleur system it is immediately put right under the sprocket. If the sprockets were not provided with a special profile, chances would be great that the chain is not exchanged. The profile in the sprockets also ensures that the chain can be changed if it is heavily loaded.
For a good operation of the index system, it is important that all chain sprockets are of the same type, that they are slid in the right way on the freewheel, and that the distance rings are mounted (Fig. 37). The tooth shapes and corresponding parts have been given separate names for the different parts manufacturers. So Shimano has labeled “Hyperglide” and “Shimano IG,” Sachs labeled “Sachs PowerGlide” and Campagnolo labeled “Exa drive”.
Sachs has sprockets with the most extreme forms (Fig. 38). To change the chain smoothly, the chainrings and sprockets are provided with switching passages. The shape of the sprocket wheels is such that the place where the chain is running off the chain wheel in line with the place where the chain is running on the next sprocket.
The chain wheels can only be pushed onto the freewheel in one way. For most brands, the marking shall be visible to the outside. Only with Suntour the marks should be towards the spokes. The use of chain wheels of the same type is guaranteed that the switching passages connect to each other. In a cassette may therefore only sprockets have the same code number.
For the proper functioning of the index system, it is essential that the chain sprockets are all on the correct distance from each other. To do this it is necessary that the correct size washers are installed.
There are both plastic and metal intermediate rings on the market. The plastic rings are between 0.05 mm thicker because they will be more compressed upon tightening of the chain wheels. Preferably use metal rings, in order to be sure that the distance between the chain wheels is good. Also make sure when mounting that no dirt between rings and sprockets is.
Chain wheels are available in different constructions. There used to be sold chain wheels separately so that different combinations could be drawn. Nowadays, more and more chain wheels are often installed on so-called “spider arms”. The advantage of this is that there is a more rigid construction.
The chainrings are equipped with special switching passages to ensure that the chain switches easily from chainring (Fig. 42). The chain wheels have to be mounted in the correct position and are of the same type.
Between the outermost chainwheel and the crank, there is a pin that prevents the chain freezes between the crank and the outer chainring. Make sure when mounting the chainrings that the sliding pin is also located between the Crank and chainring.