How to Adjust Your Rear Derailleur
Applies to most 3-chainring derailleur systems. Adjust Front Derailleur
- How to Align a Rear Derailleur Hanger
- How To Install a Rear Derailleur
- How to Adjust Your Front Derailleur
Adjusting your rear derailleur can be frustrating. I’m hoping that this tutorial will help you understand how each component of your derailleur works, and how to set up and adjust it properly. Once your derailleur is set up correctly, most future adjustments can be done by hand. Let’s get started!
Rear Derailleur Components
How They Work
Almost all modern derailleurs 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 derailleur 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.
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.
The B-Screw controls the derailleur 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 derailleur 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 derailleur 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.
The cable tension adjuster defines how far up or down the derailleur 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.
Now that the derailleur is adjusted, always apply a drop of lubrication to the derailleur’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 derailleur adjustments… have fun!
- Jim Langley: Rear Derailleur Adjustment
- Park Tool: Rear Derailler Adjustments
- Sheldon Brown: Derailer Adjustment
- Bicycle Torque Specifications
- Park Tool HXS-1.2 Hex Wrench Set
- Park Tool Wrench Combo Set
- Tri-Flow Superior Lube
- Park Tool SA-3 Heavy Duty Shop Apron
- Park Tool SK-3 Starter Mechanic Tool Kit
- Park Tool PK-3 Professional Tool Kit
Discuss this topic in the Derailleur Forums
Hi everyone,Ive got a 2nd hand marin bobtail trail. I get it indexing up nicely,wont go down well. cables,hanger seemed ok,derailleu not bent but a bit worn an sloppy,so i replaced it. bought a nice deore m592 shadow on ebay.i didnt need a long cage but it was a good price. At first it seemed fine. now after a few months an cpl months not using ,its doing it again.Its all lined up straight.ive jus...Read more
Hi All, First post on this forum. Simple question - there are various models of Shimano Revoshft shifters- RS35; RS41; RS45; RS47. As I need to replace one of these, as long as the gear number matches - are they all compatible? Phil...Read more
I've tried searching for YouTube assistance but to no avail. Cycled to the shops this morning and the gears weren't functioning, had a look and something has gone horribly wrong. It's as though the chain is suddenly inches longer than it should be and it isn't holding any tension unless the derailleur sits all the way back (image attached) almost so the chain is touching itself as it travels throu...Read more
I've got a problem with the front derailleur on my 21 speed mountain bike. The bikes chain keeps moving to gear one or even slipping off the chain entirely on the front when I try to ride it. I use this bike to get around my college campus, so I use this bike every day, so I need this bike to work. The bike in question is a 1996 Marin bolinas ridge mountain bike I got at a garage sale years ago ...Read more
I'm brand new to bike maintenance, and I have incredible difficulty getting my front derailleur to shift into the third (highest) gear, and then staying there. I don't know if the problem is with the shifter or the derailleur, and I would really appreciate any help. derailleur: shimano (that's all I know about it) shifter: a cheapy gradient thumb-knob shifter. No clicks, no numbers, just a - and...Read more
Bought a bike from our neighbor for my husband, 1990ish Schwinn Woodland. When he tried to ride it, realized it doesn't shift gears at all. Where do we start to look at what could be wrong?...Read more
I fell from my bike at quite the speed, I got injured pretty badly and this happened to my bike as well, is there a way to fix this or do I need to replace https://imgur.com/a/xlGbC...Read more
Hi. I just bought a used bike and had to change the inner tube in the back wheel. Putting the wheel back on I forgot to reattach the brake arm. I jumped on the bike and almost immediately the wheel locked up. I've taken everything apart and put it back together again, but the wheel just won't move. Does anyone know what I messed up here?...Read more
This concerns a Shimano Tiagra 4600 2x shifter. There is travel remaining in the rear deraileur, but none in the shifter itself. I can't reach the two biggest cogs using either of the front chainrings. I did dump the bike, albeit not hard. However, that accident caused the shifter housing to become out of line with the handlebars. I suspect either my repair efforts or the crash have damaged t...Read more
First bike in 7 years and I'm recently experiencing Ghost shifting, I know little to nothing about repairing bikes and I'm in need of help of how to stop the bike from shifting on its own it is very frustrating and makes it difficult to ride at times...Read more
I have vintage Charger brand gear levers and I am wondering if they'll work with Suntour VX derailleur as well as derailleurs that say index system....Read more
Hi. Sorry I dont know if this is in the right section of the forum. I just got a mtb for the 1st time as an adult. On the left hand side of the handle bars where you can change for 1 to 2 to 3. When I change from 1 to 2 it doesnt alwaya do it. The dial moves to 2 but the bike makes an awful noise and no matter how much i pedel it still makes that noise. If I then go into 3 it then after a good ...Read more
I am riding a Bianchi 928 with SRAM Red components. I have a 10 speed 11x28 cassette. I am replacing my rear derailleur since the guide pulley cogs are now worn to sharp points. The present derailleur has a short arm. SRAM seems to have 3 sizes of derailleur arms for a 10 speed cassette; short, medium, and long. The 28 cog gear still works will with my short derailleur. I heard that yo...Read more
I have a Deore LX shifter like on this photo The push button at the bottom doesn't catch the piece inside unless I press slightly up when I shift. Is that fixable or do I have to change the part? Thanks!...Read more
Yesterday 5 meters away from my destination my rear derailleur suddenly "snapped". I though at first that the cable broke, but no. I flipped the bike around and started shifting and it looks like it kinda "works" but it suddenly doesn't want to shift into the lowest gear (the biggest gearsprocket). I rode back home just fine, but I am a little bit worried and I am not sure what happened. It is a ...Read more