We recently wrote about how one would adjust a Shimano front derailleur, so in this article, we will look at how to adjust a Shimano rear derailleur.

My own education in bicycle maintenance began when I first started seriously riding and racing at age 13 (as baseball just wasn’t exciting enough for me). With the help of my father, we built a nice little bike shop in our basement, and I taught myself how to not only fix my bicycle but eventually started working on bikes from all of my neighbors (for a small fee, of course!).

Bicycle repairs can be quite expensive at a bike shop. In some cases, repairs account for over 50% of their revenue, but simple tasks like fixing a flat, adjusting brakes and derailleurs, and even repairing a broken chain can, in most cases, be done at home. Some basic tools one will need for home bike adjustments are tire levers, a Phillips screwdriver, and a set of metric Allen wrenches, and you would be surprised at what you can fix on your own (or ask for a Park Tool set for Christmas as I did!).

This piece will focus on Shimano rear derailleurs and how to adjust them for proper shifting. We are focusing on Shimano rear derailleurs as it is the world's largest bicycle component manufacturer. The other two major component brands are SRAM and Campagnolo, which will largely operate similarly, so the adjustment steps outlined here should also apply.

As the majority of derailleurs in circulation are mechanical (use a cable to shift the gears), we will focus this article on those types. The other type of rear derailleur is electronic and the adjustment for that type of derailleur is a bit different, thus we will leave those instructions for another day!

Shimano’s mechanical rear derailleurs include Dura-Ace, Ultegra,105 (all of which are available in electronic), Tiagra, Claris, Sora, and Tourney to name a few.

Basic Rear Derailleur Parts

A rear derailleur is the mechanism on the bike attached to the rear dropout on the drive side of the bicycle and is the unit that will move the chain along the rear cassette.

A rear derailleur will consist of the following prices: a main body with two pivots called knuckles (for moving the cage), a cage that straddles the chain, a cable adjuster barrel and anchor point, two pulleys (guide pulley up top close to cassette also referred to as upper jockey wheel and idler pulley that holds tension on the chain or lower jockey wheel) and two limit screws (a high and low).

Here are the steps one needs to follow for rear derailleur adjustment:

Step 1: Cleaning

Like any mechanical part and even the front derailleur we’ve already written about, your rear derailleur will work considerably better when it is clean of all road grime and grit! And one of the more essential parts that interact with the rear derailleur is the chain, and keeping it clean will be paramount in the effectiveness of your bike’s shifting. Simply wiping down the chain a few times a week with a light degreaser on a rag, followed by adding a small amount of lubricant, will keep your bike shifting smoothly for longer!

Step 2: Cable Tension

The rear derailleur attaches to the bike frame by screwing the unit into the rear derailleur hanger on the drive side of the bike, which can get bent from crashes or the bike falling on the drive side and, in many cases, is replaceable on the frame.

Starting with your bike shifted into the HARDEST gear (big chainring up front and smallest cog in the rear), loosen the anchor bolt, pull the rear derailleur cable tight, and retighten down the anchor bolt.

Step 3: Limit Screws

The next step is to check the limit screws (see picture above) to ensure the derailleur is not shifting the chain off the inner or outer cogs.

There are two limit screws. One might be marked “H,” and the other might be marked “L,” but both are found near the lower knuckle (b-knuckle). The high-limit screw prevents the cage from moving too far in and allowing the chain to drop inside the smallest cog. The low-limit screw is used to ensure the cage does not shift the chain out over the largest cog and into the spokes. In most cases, a small Phillips screwdriver will move these limit screws.

To adjust the low limit screw, one would shift the bike into the largest sprocket or cog (easiest gear) and turn the screw until the chain aligns with this last cog. If the pulleys move the chain beyond the largest cog, turn the screw inward until this movement is corrected. For the high-limit screw, you would shift your bike into the smallest sprocket or cog in the rear (largest or highest gear) and turn the screw until the jockey pulleys line up perfectly with this cog. If aligned correctly to the cog/pulleys, your chain should move smoothly when turning the pedals.

Step 4: Fine Tuning Shifting

Most rear derailleurs will also have a barrel adjuster near where the cable is anchored on the body, allowing you to fine-tune the cable adjustment here. If your chain skips when you shift to a lower gear, give the barrel adjuster a half-turn counter-clockwise. If your chain has problems shifting to a higher gear, turn the barrel adjuster clockwise!

Step 5: Testing

After making the adjustments outlined above, it is time to test your bike’s shifting. I find it best to use in an indoor stand (like pictured below) to allow you to effectively shift through the full range of gears. Keep in mind shifting on a work stand such as this does not put the same amount of tension on the gearing as it would when riding outside, so you might have to do some additional fine-tuning after your first outdoor ride.

Final Thoughts

Once you’ve mastered adjusting both the rear and the front derailleur, you can turn your attention to other aspects of bicycle maintenance (brakes are not that hard to adjust!) If you need additional help, check out the Expert Journal here on Curated for more Cycling articles.