How To Adjust Your Rear Derailer
Applies to most 3-chainring derailer systems.
Adjusting your rear derailer can be frustrating. I’m hoping that this tutorial will help you understand how each component of your derailer works, and how to set up and adjust it properly. Once your derailer is set up correctly, most future adjustments can be done by hand. Let’s get started!
Required Tools
You’ll need a rag, a phillips screwdriver, a 5mm allen wrench, and a light lubricant like Triflow or Phil Wood Tenacious oil.
Rear Derailer Components
How They Work
Almost all modern derailer function the same basic way. They are designed to move (or derail) the chain from one sprocket to the next. The upper guide pulley (or jockey pulley) moves the chain in both directions. For instance, when you want to climb a hill, you shift down to a lower gear. This pulls the shift cable and forces the guide pulley to change to a bigger sprocket. When you want to go faster, you adjust the shifter to a higher gear. This releases shift cable tension and allows the derailer springs to pull the guide pulley back down to a smaller gear. Each time you shift gears, the length of chain changes. The lower tension pulley is spring-loaded to take up this slack.
Limit Screws
There are 3 adjustment screws - the B-Screw (B-tension adjustment), the H-Screw (high gear limit stop) and the L-Screw (low gear limit stop). Adjustments on these screws should always be made in 1/4 turn increments.
B-Tension Adjustment
The B-Screw controls the derailer body’s angle in relation to the sprocket-set. Shift down to the largest sprocket and check the distance between the guide pulley and the large sprocket. If the guide pulley is rubbing on the sprocket, tighten the B-screw clockwise to increase tension and move the pulley away from the sprocket. If there is a large gap between the pulley and sprocket, loosen the B-screw until the pulley rubs the sprocket, and then tighten it until it just clears.
High Gear Limit Stop
The H-Limit screw high gear limit stop prevents the guide pulley from shifting any further past the highest gear and into the axle. In order to adjust it properly there must be no tension on the lower inner cable. If you feel tension, loosen the cable adjuster until there is none. Now check from behind how the chain is riding on the smallest sprocket. If it looks like it wants ride off into the axle, tighten the H-screw clockwise until it lines up. If it looks like it is rubbing on the next gear, loosen the screw until the chain is nicely centered on the sprocket. Now re-adjust the cable tension until the derailer shifts smoothly down to the next gear.
Low Gear Limit Stop
The L-Limit screw prevents the guide pulley from shifting any further past the lowest gear and into the wheel spokes. Shift down to the lowest gear, step behind the bike, and check how the chain rides on the sprocket. If it looks like it wants to ride into the spokes, tighten the L-screw clockwise until it is centered on the sprocket. If it looks like it wants to shift down, loosen the screw until it lines up. As an extra precaution you can use your thumb to gently push the derailer body and make sure the chain will not run into the spokes, as this could obviously have a nasty effect on both you and your bike.
Cable Adjustment
The cable tension adjuster defines how far up or down the derailer moves. Step back so you can see the chain and sprocket alignment, and then through the gears in both directions, first shifting up two and down one, and then down two and up one. The chain should look centered on each sprocket. If it is rubbing on a larger gear it means there is too much tension on the cable. Loosen the tension by turning the adjuster clockwise. If it wants to jump down to a smaller gear it needs more tension. Increase the tension by turning the adjuster counter-clockwise.
You can also use sound to check the adjustment. There is always a base-level of noise that can be heard in every gear. This noise will increase in a slightly different way depending on which way the tension is out of adjustment. If there is too much tension you will hear a metallic rubbing sound, but if there is too little tension you will hear a clicking noise as the chain tries to jump to a smaller sprocket. There is usually a cable tension adjuster on your shift lever. With practice you will be able to make small cable tension adjustments while you are riding.
Lubrication
Now that the derailer is adjusted, always apply a drop of lubrication to the derailer’s many moving parts. This will help prevent wear from dirt and rust, and it will keep your gears shifting smoothly. Wipe away any excess lube and take your bike for a test ride to make sure all the gears are working smoothly.
That concludes our tutorial on rear derailer adjustments… have fun!
Resources
- Rear Derailleur Adjustment (Jim Langley)
- Rear Derailler Adjustments (Park Tools)
- Derailer Adjustment (Sheldon Brown)
- Derailer, Not Derailleur! (Sheldon Brown)
- Shifting your Bicycle’s Gears (Sheldon Brown)
- More Derailer Adjustment Info (Bicycle Search)
Repair Guide »
Derailer, Drivetrain, Gears, Rear Derailer
Comments RSS
You mention not to use WD40. I have heard that advice before and it was suggested to me to use GT85 instead, what is your take on that?
WD40 is a solvent, good for stripping rust and un-sticking seized parts. It is not a lubricant and should never be used on your drivetrain, cables, bearings, etc… I only mention it because it is a common misconception. In my years as a mechanic I saw many damaged bicycles because people thought it was good to use WD40 on their chain - or even worse - in their bearings.
I don’t know GT85, as I’ve never used spray lube before. It doesn’t look like something I’d use. Regular bicycle chain oil always works the best. Triflow or 3in1 works well for cable housings and pivots, and obviously a good waterproof grease for bearings.
More about the harmful effects of WD40 here:
http://bicycletutor.com/no-wd40-bike-chain/
Very well done and helpful, Alex. Thanks for your efforts and looking forward to more lessons.
Great job with the video. I’ve been a dedicated cyclist for over a decade, so I appreciate it when a “brother” shares his passion for our wonderful sport. Keep’m coming!!
Thanks for all your comments and support. I learned a lot making this video (particularly, that making videos isn’t easy), and I’m really excited to record the next one!
Yeah! I just “stumbled” here, and I was hoping that with only two videos it wasn’t an old-dead site… luckily, I see that it’s young and active!
Keep up the good work, see you around!
Alex,
Just found your site through bike forum. I hope you can keep these up, they are proving most informative. Well done.
Just arrived here via Stumble. I will be subscribing to the feed as I need all the help I can get when it comes to fixing my bike.
Great video. Thanks !!!!!
Fantastic video! I was actually doing some research on the front derailer when I stumbled across your site. Maybe we will see a video on the front derailer soon! Brilliant job as it makes life so much easier for a novice like me.
NIIICCCEE!
You say not to use WD40 on my bike. I use TONNES of the stuff. Maybe thats why all of the gears click…
Hi great job on the videos. Unfortunately your advice has come a little late and I used WD40 on the chain and sprockets about 2 days ago to clean them. I did use chain oil afterwards but should I do something else to remove the WD40 first ????
Hi Eddie,
No you don’t need anything to clean the WD-40, as it already acts as a cleaner. You can go ahead and lube the chain, it will be fine.
ALex,
A comment from Downunder (Australia). Well done. The first problem I was researching was on how to adjust my derailer and presto - your site answered ALL my questions. I was determined to make up a similar site myself when I learned enough but you have done that.
A link to your site was found at a Sheldon Brown’s site (bike junky) (http://sheldonbrown.com/derailer-adjustment.html) and was useful but yours takes the cake.
Steve
Thanks for the fine and informative video tutorials Alex. As an avid cyclist but not a mechanic these videos have proven quite helpful.
Keep up the outstanding work and assistance to all of us!
Great site. I found it through Gerry Lauzon’s How to Fix Bikes site, with his link to your WD-40 video. The only use I’ve found for WD-40 on my bike was in removing the fixed cup from the bottom bracket, at which time I sprayed repeatedly inside and outside the cup between turns on the fixed-cup removal tool (Sheldon Brown’s home-made version.) I don’t think I would have gotten it off, otherwise.
I’ve now linked to you from my site and written a post about it.
Alex,
Very useful site already recomended to my tri club team mates.
Just one comment on rear mech adjustment. You mention the allen key in your intro but not during the adjustment process. It would help to tell folks how to use it to adjust the cable tension in the case where the cable adjuster runs out of travel or the case where you are replacing the cable or reinstalling the mech.
Graham.
Graham, thanks for the feedback. I’ve added setting up shift cables to my list of future tutorials.
Did this one too (as well as the front). Thanks again for the help! Keep then coming!
Man now I don’t have to pay someone else to do the work I can and I can spend my money on gear. this a great site that will help and encourage all cyclist. GREAT job, some videos on safety would be good too, maybe on how to merge & avoid traffic. This is where people get in trouble. Cheers mate for a great site. Godspeed, and peace.
I can’t even describe how happy I am I just stumbled across your website. I’ve been trying to find a clear, easily understandable tutorial on how to do derailleur adjustments for ages. Thanks to you I no longer need to fork over money every other week to have my bike adjusted into tip top shape. Thanks a million and happy riding!!!
I found that my chain tension is too low. When I stop peddling quickly, the slack in the chain can drop the top length of chain down and it catches under a piece of the frame. Can the tension be increased on the derailer?
Hi Ron, no you can’t make up the tension at the derailer. It sounds like your chain may be too long? If that’s the case, check out this tutorial.
Alex-
Excellent job on both front and back derailleur adjustments, I was becoming quite weary of driving 30+ miles one way to my mechanic, and your videos have saved me bunches. I’ve invested in a repair stand since your videos have put the pieces of the puzzles together. I spend more time riding instead of money. Thanks !
I’m an on-again off-again cyclist, and have the problem of constantly needing to re-figure-out-the-hard-way how to fix my bike. This, predictably, puts me more off the bike than on. With your site, I can now look forward to fixing things quickly and getting back on the road.
Thanks for explaining the key issues in clear language and for providing just enough detail for reference. If your goal is to keep more people happy and on their bikes more of the time, then you are succeeding, my friend!
Thanks - the rear derailleur adjustment video was superb!
Thanks for providing these videos, especially this one!
Setting the bike gears has always appeared a mysterious art to me!!
Sites like this represent the best of what the internet can offer - sharing knowledge and experience, making life easier for everyone.
Thanks again.
You forgot to mention what the barrel adjuster does.
It’s explained around 3min into the video and in the text under ‘Cable Adjustment’.