dérailleur gear
Quick Summary
A derailleur is a mechanism on a bicycle that shifts the chain between different gears. This device allows riders to change the gear ratio, making it easier to pedal on varied terrain.
The derailleur operates by moving the chain from one exposed gear to another. On a bicycle, there are typically front derailleurs that move the chain between chainrings connected to the pedals, and rear derailleurs that move the chain between sprockets on the rear wheel. By combining different sizes of chainrings and sprockets, a bicycle can have many gear ratios, providing a theoretical maximum of up to 30 different combinations. Modern systems use levers or grips to control the derailleurs, making gear shifting more precise and less skill-intensive than earlier methods.123
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