THE DERAILLEUR: EVERYTHING YOU NEED TO KNOW
What is a derailleur?
The derailleur is the bicycle part that allows you to shift between gears. A derailleur is controlled by a shifter. The shifter can retract or release the cable, which changes the derailleur's position. The derailleur then shifts the chain to a different cog.
Derailleur chain tension
Besides shifting gears, the rear derailleur also maintains chain tension. Some derailleurs now feature a clutch, which further tightens the chain. This is often used on single-cage bicycles, gravel bikes, and mountain bikes . The clutch operates through a mechanical system that adds resistance to the derailleur cage, reducing the chain's chance of bouncing over rough terrain, resulting in a quieter ride and a reduced risk of chain loss. You can often deactivate this clutch with a lever, making it easier to remove the rear wheel.
Derailleurs - What types are there?
Derailleurs come in all shapes and sizes, with various specifications to choose from. Consider the number of gears, the maximum cassette size, and the derailleur 's capacity. Capacity is the difference between the largest and smallest cogs on the front and rear, combined. This is important because the derailleur must be able to keep the chain under tension. Many derailleurs are available with different cage lengths, with a longer cage providing greater capacity.
How do I adjust my derailleur?
Adjustment is key! A properly adjusted derailleur means a smooth ride. There are three key aspects to consider: b-tension, which controls the distance between the guide pulley and the cassette; limiters, which prevent your chain from dropping off; and, of course, cable tension, which ensures smooth shifting. Correctly adjusted b-tension allows the derailleur to move smoothly between cogs, while limiters limit the derailleur's range of motion to prevent over- or under-running the chain. Proper cable tension is crucial for precise shifting without excessive resistance or chain skip.
Some bicycles these days come with an electronic derailleur. These require much less frequent adjustment because there's no longer a cable that can stretch and wear out.
What is a derailleur hanger?
The derailleur is a fragile component. To protect it, it's mounted on a derailleur hanger. The derailleur hanger is made of a softer metal designed to flex, absorbing impacts instead of the derailleur itself. If all your other adjustments are fine, but it's still shifting poorly, your derailleur hanger may be bent and need to be aligned or replaced. The derailleur hanger is frame-specific and sometimes even different depending on the derailleur.
The derailleur is essential for smooth shifting and an efficient riding experience on your bike. With knowledge of chain tension, different derailleur designs, adjustment, and the importance of derailleur hangers, you can ensure your bike always performs optimally. Our experts in the workshop are ready to help you with all your questions and maintenance, so you can keep riding worry-free, whether you're on the road, on the trails, or in the city. You're always welcome in our store for expert advice and professional service.