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 am having some issues with a SRAM Apex rear shifter and the rear derailleur. I have pulled the shift cable tight and through the holding bolt of the rear derailleur and the barrel adjuster is turned all the way in clockwise. Shifting to easier gears works well, but shifting to the harder gears does not. The shifter clicks but the cable does not stay seated in the spool and remains slack when shifting to harder gears from easier gears ( see picture).
Read more >>
Hi I need some help my grandson has messed with the derailleur on his bike it no longer works and you can only get the pedal to turn a little bit and it jams and wont turn I don't know any think about bikes so I need help to try and fix it for him... Read more >>
Just bought a used MTB with several XT components and some lower quality ones.
I can't figure out the model of the rear derailleur
It's Shimano, but I don't know which one
Has anyone an idea?
Thanks... Read more >>
I've a 9speed DA that is fine going up & down the gearing, but put a load on 1st, 2nd & sometime, the chain skips. I cannot get my indexing right to get rid of it, any thoughts?... Read more >>
I inherited a bike with an Eddy Merckx frame about a year ago. The bike has some Campagnolo components, including rear shifters which have an issue. I'd rather repair the shifter than replace it because the bike as some sentimental value, and the longer I can go without replacing parts the better.
The thumb shifter usually locks when I try to shift, but if I hold the brake lever over to the right with my index finger the thumb shifter functions again. My mechanic told me that a spring in the shifter needs to be replaced and that it can be hard to identify a compatible sprin... Read more >>
I have a Shimano Deore SL-M570 shifter (circa '00) that has a lot of up and down play in the thumb lever for the front derailer. Unless I press the thumb lever upward toward the body of the shifter, the loose condition causes it to miss the pawl to shift from the second to the third chain ring. If I open up the bottom cover on the shifter, it would appear that it can be tightened by the hex bolt that is visible, but there is a small metal plate underneath it, with two tabs that stick up on two sides of the bolt, apparently preventing it from turning ( Read more >>
Let's start off by saying I'm not mechanically inclined but like to fix on my own when able. I have, I'm guessing, a 15-20 year old 15 (3x5) speed Magna Outreach and the right 5 speed grip shifter (SRAM MRX 170-51) is broken internally and apparently 5 speed shifters are rare nowadays. My question is, will any shifter do or does it have to be compatible with the rear derailleur? I currently have a Shimano SIS rear derailleur. The reason I ask is, the old shifter has gear 1 almost 180 degrees away from gear 5. On the only 5 speed SRAM grip shifter I can find on the internet (SRAM MRX Comp), ... Read more >>
HI Guys,.. Got a real nice Trek 7.4 from craigslist the other day and the bike does ride like a dream... at least from what I'm used to (Wal-mart!)... But it does seem to have a gremlin that I can't figure out. The chain will randomly come off the front gear set to the inside. I've checked the inner limit setting and it's set so that there's just barely any clearance between the chain and the derailleur when both front and back gears are set to the lowest gear. It won't do it everytime,.. I don't see how it's even coming off, but it's happened 3 times in 2 days and it's driving me nuts... Read more >>
Novice question probably - so please be kind
Unable to shift to small cogs on rear derailleur...so, I decided to do some cleaning of the derailleur as it was all gunked up. All good so far (except the shifter at the front still seems to be clicking to nothing - so perhaps I need to investigate the chain tension) but I've now created another problem with the chain.
Having dismantled the pulley and jockey wheel and cleaned them, and removing the chain... Read more >>
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 >>