Rear Derailleur Adjustment – Bike Servicing

I was thinking the other day about just how simple our bicycles really are. Think about it, they haven’t changed dramatically over the years (yes, tires and shifting have improved, but the bike is still basically the same). Probably the most complicated device on our bikes though is the rear derailleur.

Maybe complicated isn’t the right word here. While not as simple as some of the other components on your bike, your rear derailleur does require periodic adjustment to keep the shifting smooth and crisp. Most people shy away from adjusting their rear derailleur systems themselves but I say “roll up your sleeves and find out just how simple it really is to adjust these components”.

Jim Langley has been around bikes a long time and knows his fair share about bike servicing. His article on rear derailleur adjustment really makes the topic seem easy. Let’s review the steps that you would take to service and adjust your bike’s rear derailleur.

Adjusting Your Bike’s Rear Derailleur

Step 1 – Put Bike in Stand

One of the first investments I made when I decided to start “wrenching” on my own bikes was to purchase a bike stand. I tell you that these devices are worth their weight in gold because they do such a good job of holding your bike for you. If you don’t have a bike stand though, this article suggests using the bike carrier attached to your vehicle (interesting, I’ve never heard that suggestion before). If you have neither then you will just have to lean the bike up against a wall or find some other way to keep it still.

Step 2 – Check the Cables

OK, now its time to look at your derailleur cable. Worst case scenario (if the cable is frayed and kinked) is to replace the entire cable. If your cable seems to be still in good shape then all you need to do is remove the cable from the derailleur housing and clean and lubricate it. Lubrication helps remove the friction between the cable and the housing which allows for better derailleur movement.

Once lubricated, you can re-thread the cable back into its housing. You will want to make your fine tuning adjustments to the derailleur before re-securing the cable with the anchor bolt though. Here’s how. Once re-routed, locate your barrel adjuster and turn your barrel adjuster (clockwise) as far as it will go. Now back it off one turn counter-clockwise to complete this adjustment.

For a detailed description of the derailleur barrel adjusters, read the article “How to Maintain Your Rear Derailleur – It’s Not Really That Scary”.

Step 3 – Check Bike Chain Movement

Now we want to check to see whether the derailleur arm is moving your chain properly and as we are testing this out, we also want to ensure that the derailleur arm can move the chain to both the largest cog as well as your smallest cog (i.e. the high and low end movement).

You will need 2 hands for this procedure but it really is quite simple. Your left hand is going to be on your pedal, turning your cranks, while your right hand (thumb actually) moves the derailleur arm by pushing it. This sounds more complicated than it actually is. See the picture of this thumb pushing technique here.

Step 4 – Adjust the High and Low End Movement (if required)

If your chain does not shift all the way over to your largest back cog or to your smallest back cog then you will need to adjust your high and low end screws. Check out the article “How To Adjust a Rear Derailleur”, for the correct high and low end screw adjustment procedure.  This sounds much more difficult than it actually is, believe me!

Step 5 – Re-Secure the Cable Using the Anchor Bolt

Now that you’ve lubricated your cable and checked the high and low end movements, you are now ready to re-secure your cable to the derailleur with the anchor bolt. To do this properly you will need to keep the cable fairly tight while tightening it. The easiest way to accomplish this is to grab the end of the cable with a wrench and lightly pull the cable tight (bit not too tight). Once cable is tight, tighten up the anchor bolt.

Now that the cable is reconnected, you should check the derailleur movement once again throughout its range. You may need to make small adjustments to it and this is where the barrel adjuster comes back into play. You may run into 2 scenarios where a minor adjustment is necessary; chain hesitates or the chain overshifts.

Bike Chain Hesitates (Scenario 1) – if while pedalling, the chain hesitates moving between gears (i.e. cogs) then simply unscrew the barrel adjuster ½ turn counter-clockwise. Now go and recheck the chain movement. Keep doing this adjustment until your bike chain moves effortlessly between all your gears.

Bike Chain Overshifts (Scenario 2) – This is the exact opposite of scenario 1 and as such the procedure will also be opposite to Scenario 1. In this case, turn the barrel adjuster ½ turn clockwise and then re-try shifting your chain. You will want to keep re-adjusting until your chain moves precisely between all your cogs.

So there you have it, a very simple bike servicing technique to adjust your rear derailleur. Why not give it a try and let me know how it works out for you. I am always interested in learning from the experience of my readers.

Until then ride safe and happy bike wrenching.

Robert Flaherty

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