Basic Rear Derailleur Knowledge

If there is one thing that confused me most about my bikes at first, it was how the rear derailleur works. Let’s shine some light on this mysterious piece of tech, shall we?

What do all these screws do?

On first glance, the derailleur is this mysterious piece of metal with screws sticking out of it all over. For basic maintenance, you really only need to know two of them. Let’s break down what each of them controls!

High Limit Screw

Usually marked with an H, this screw controls how far away from the wheel the derailleur can go. Turning it counter-clockwise pushes the derailleur further out while turning it clockwise allows the derailleur to rest closer to the wheel.

Low Limit Screw

Usually marked with an L, the low limit screw controls how close the derailleur can get to the wheel. If it pulls too close to the wheel, it can pull the chain off the inside. This can lead to a lot of cursing in frustration as you wrestle it out, or worse, broken spokes. Turning it counter-clockwise pushes the derailleur further out while turning it clockwise allows the derailleur to rest closer to the wheel.

Adjusting your cable tension

Seems simple right? Well, it is and it isn’t. There are actually two parts that can adjust your cable tension. The first, most obvious, is used to make large adjustments. To adjust this: shift into your highest gear, loosen the screw that clamps the cable, pull the cable finger tight, and retighten the screw!

The second way is using the barrel adjuster, which will generally be located on your front shifter or directly attached to your derailleur. The barrel adjuster is used to make small adjustments to your cable tension, mainly during indexing, which we will get into next time.

Tune in next time, when we take a closer look at how to use all of this to ensure your shifting remains buttery smooth!

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