How To Tune your Rear Derailleur

Posted on Oct 28, 2013 in News | 0 comments

How To Tune your Rear Derailleur

Ah, the rear derailleur – the source of much frustration among novice and experienced cyclists alike. When poorly tuned, it can cause plenty of clicks, skips, and mis-shifts, often at the most critical moments in your ride (grinding uphill, anyone?) But with a little know-how, you can make sure your gear changes are silky smooth and be the envy of all your ghost-shifting friends.

Your derailleur has two methods of adjustment: limit screws and cable tension. Let’s start with Phase 1: the limit screws. Take a close look at your rear derailleur for two screws labeled “H” and “L”. You can see them in this photo.

Tightening and loosening these screws will limit how far the derailleur will move in either direction—hence the name, “limit screws”. The “H” and “L” correspond to the high and low gears on your rear cassette. Keep in mind—the low gear is the largest cog on the cassette, and the high gear is smallest.

To properly adjust them, clamp your bike in a repair stand, so the rear wheel can spin freely. Shift into the smallest cog in the rear. Then, loosen the Allen bolt that’s holding the derailleur cable tight. As you pedal the bike, push the derailleur toward the spokes. When the derailleur is pushed to its max, the chain should land directly on the largest cog. Does it go over and into the spokes? Tighten down the “L” limit screw. Does it only reach to the second-largest cog? Loosen the “L” screw. Release the derailleur. It should fall directly into the smallest cog. If it lands in a larger cog, loosen the “H” screw until it falls into place.

Once you have the limit screws set properly, you rarely have to play with them again. You’re ready to move into Phase 2: cable tension adjustment.

Make sure your shifter is in the highest gear, and your chain in the smallest cog. Pull the derailleur cable taut, and reattach it firmly to the derailleur. Now run through your gears. The chain should land easily on each gear, with one gear per click. If the chain is popping or slipping, you need some cable adjustment. You can tweak this by rotating the barrel adjuster on your cable. Often, it’s found directly adjacent to the derailleur, as seen in this picture (it can also be found near the shifter rather than the derailleur, which you can see here).

Start in the smallest cog and move up through the gears, noticing where your chain skips. To fix it, simply turn the barrel adjuster the way your chain is having trouble going. If your chain doesn’t want to move up to the biggest cog, turn the barrel adjuster a half-turn towards the spokes. Keep doing so until the transition is seamless. If it’s having trouble dropping down to a smaller gear, turn the adjuster toward yourself. The same logic applies for a handlebar barrel adjuster: Turn it towards yourself to help it into a smaller gear, and towards the front of the bike to help jump into a larger cog.

Sounds simple, right? For some reason, rear derailleur adjustment is one of the most mind-boggling repairs for many cyclists. But with a little practice, you’ll be among the few and the proud – the masters of the fine art of derailleur tuning.

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