1. How to Adjust Your Rear Derailleur
Applies to most 3-chainring derailleur systems. Adjust your Front Derailer
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!
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.
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.
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!
I just changed the Altus lever (ST CT-15) on a mountain bike that had been sitting in my basement for a while.
Using the lever, I can't have the front derailleur move up or down (left or right) for an unknown rea... Read more >>
I have a Scott Sub (hybrid) from 2008. The stock components (mostly Shimano mountain bike components) were old and wearing out so i decided to strip the bike and replace pretty much everything with new and upgraded components. I decided to change the drive train to road bike components (a 10-speed rear cassette and a two-chainring set up front) and went about purchasing them.
Put everything on with the last major part being the front derailleur and it was here I ran into a problem. I’d bought a Tiagra front derailleur, FD-4600-B, and when it came to attachin... Read more >>
I have a 2012 Sram Red Groupset. I was replacing the cable for the front derailleur yesterday and i must have done something because now its fucked. Now when I put the cable in and attach it to the front derailleur it will not click into the correct position. The front derailleur will still move up onto the larger ring but after I take my finger off the lever it goes back into the smaller ring. Does anybody have any experience with this? what happened? adn how do I fix this?... Read more >>
I'm quite attached to an old Mongoose "Hilltopper" mountain bike. It's perfect for it's role taking me back and forth to the metro station. Sturdy, comfortable, and not likely to be stolen.
Unfortunately, the Suntour alpha 3000 6-speed rear derailleur is toast. Is there anything I can buy that will replace it?
eab... Read more >>
Hello. I'm new to this message board - thanks for reading this.
I'm almost at my witts end with adjusting my wife's mountain bike. It's about 15 years old, Specialized brand 21 speed. Original Shimano shifters seem to be locked up - I've read that the grease hardens over the years. I tried loosening them up with Brake Clean spray, but to no avail.
I found a new pair of Shimano Shifters online (Amazon Prime) with very good reviews, so I decided to completely replace the ones that were on the bike.
The installation was easy, but adjusting the shifters - front ... Read more >>
The other day I bought a mountain bike secondhand and have been researching it's problems trying you find the best solution. I managed to reattach the rear brakes after the cable had come out of a couple holders on the frame. I put air in the tires and took it for a test run only to find that the gears, which I fully expected to give me trouble, not only don't work so great, they actually won't shift at all. Both shifters (twist shifters built into both handles) click when turned, and visibly affect the cable tension, which does seem loose to me (though I know nothing about bikes). I used the ... Read more >>
I've followed these instructions
to adjust the front derailleur on a 90's MTB with 400LX components and I think I've done things right, but the chain keeps jumping directly from the outer chainring to the inner one.
Thanks... Read more >>
My 11 speed has become an 8 speed. Thought maybe cable slipped/stretched/frayed. Nope. Limit screws are right. It wont hit the final 3 smaller gears. Physically pulled the cable and it would track down the final 3. Tightened the cable anchor. Got it to shift to the bottom but woudnt shift to the top three gears. Removed the cable from the anchor and pulled it. Started working the shifter while holding tension on the cable. Im only getting 8 detents from the shifter.
What happened to my shifter?
Thanks for the help in advance... Read more >>
I want to swap the racing handlebar brakes/gear shifters for normal v brake levers and thumb shifters - however the only affordable shifters I can find are for 21 speed (3x7) and my bike is only 14 speed (2x7). Can I set it up so that both the 2 and 3 on the left (front hub) shifter just cause it to be in 2 (because there is no 3rd gear on front)???
Hope I phrased it in an understandable way! its hard to write it out without pointing at stuff ... Read more >>
I wonder if anyone can help with an issue I'm having with my rear derailleur.
I'm not really sure how to describe this but you can see here http://tinypic.com/r/2cwogbb/8 (direct images not working...). Basically when changing gears, the mech (which has recently been professionally fitted) locked up in the stretched out position and now I can't get it back. It has happened a few times before and released itself, but no joy this time.
Sorry if this is discussed el... Read more >>
I bought a very old Mongoose mtn bike from Goodwill for commuting to/from the metro station, and would like to replace its very old Suntour 3000 alpha rear derailleur. Is there a model of derailleur I'm likely to find that will allow me to keep the index shifting? Or should I give up and buy any old other derailleur for continuous shifting?
Thanks!... Read more >>
My bicycle had been shifting erratically on its own. I downshifted and immediately after downshifting a loud CLUNK jammed my tire. This is what the damage looks like---is this ... Read more >>
i bought a raleigh mtrax ht 1.0 but the hanger from the Rear Derailleur is missing ive been in a few bike shops and they are unsure what hanger i need. i've been online and there are hundreds of different shapes and don't want to start wasting money on hangers and they don't fit so if anyone knows the type of hanger i need would be very helpful
here is a stock pic of the bike
I have found what one... Read more >>
i have Hunter Shadow from years ago, probably the 80's, not a high end bike from Hunters in California.
it has 1.25" tubing. i sent it to a bike shop a year ago because I couldn't remedy it and they did a home made type of repair. the bike would never shift into low. same after they repaired it. no difference. the derailleur is the wrong one as it had no cable stop to attached the sheath or jagwire that fed up from the bottom cable stop.. now to the chase. i removed the front derailleur and the small and large chain rings and now have a 36 tooth middle chain ring left on the same crank... Read more >>