Chainsets and bottom brackets are responsible for transferring the strength of the cyclist to the chain, which in turn transfers it to the rear wheel of the bike. They consist of one or more chainrings attached to the cranks at the end of which are located the pedals. There is one crank for the right leg and one for the left and they are mounted at 180 degrees from each other, joined by the bottom bracket.
Chainrings are a set of cogs that are responsible for making the bike chain move, transmitting the movement to the rear wheel through the cassettes. There are different sizes of chainrings to increase the drivetrain force and therefore adapt the gear to the different conditions of the terrain being cycled.
The bottom bracket can be described as the heart of the bike, since it is one of the most important parts of the bike, although it is not spoken so much about since it normally cannot be seen. Almost all bottom brackets are airtight and with the joints sealed, they are assembled under pressure and cannot be disassembled, but they can be greased to improve their performance.
These brackets do not allow for much maintenance or repair, which is why if they break,you usually have to replace the entire chainset.
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