Chain / chainring / cassette / rear derailleur - wear and tear

Chain

My chain on the ST3 lasts about 10,000 km. If I change it, I always change the 11th sprocket as well. This is the one I ride most often. Every 2nd chain change - depending on wear - I also change the 13/15/17/19 sprockets.

> See FAQ - 'Chain - measure wear'
> See FAQ - 'Chain - number of links / brand?
> See FAQ - 'Maintenance - chain and belt - what does Stromer say?

Stromer has used and continues to use different rear derailleurs and cassettes throughout the evolution of its models. They all have one thing in common: they are a wearing part and without maintenance their service life is noticeably shortened. Depending on the model, the cassettes have a modular design, meaning that individual sprockets or sprocket groups can be replaced. When this must/should be done can be recognized on the one hand by the appearance of the sprockets and on the other hand a replacement is indicated by the jumping or slipping of the chain.

A chain can already be out of tolerance at 4,000 km, but with good care and 'smooth' shifting it can also last over 10,000 km. They wear out at different rates depending on the frequency of shifting and use of the gears.

The sprocket on the right has definitely been running for too long. The mechanical wear is clearly visible. It would also massively reduce the service life of a new chain.

Rear derailleur

The rear derailleur has two externally visible wear parts, the two derailleur pulleys. They have teeth made of rigid PVC and plain bearings which are also subject to mechanical wear. The pulleys have no load-bearing function and only serve to guide the chain. At Shimano, there are differences in the higher quality product groups and the guide pulley must be installed at the top and the tension pulley at the bottom. In some cases, these are also bound to the direction of rotation (arrow on the roller).

Replacement is necessary when wear is clearly visible or the rollers no longer turn smoothly.

The rollers on my Di2 rear derailleur are still ok after 30,000 km.

The rear derailleur also contains mechanical parts that are subject to fatigue rather than wear. For example, the tensioning set is responsible for the tension of the derailleur arm. It can break and the arm becomes paralyzed. Shimano offers various spare parts for the rear derailleurs, so that a repair is possible.

Life expectancy/costs: chain vs belt

> See SHIFTING - chain vs belt - 'Comparison: costs / care / (life) maintenance'