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!
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I don't exactly know how it happened. I've been trying to fix it for days but nothing works.
So let's say you had a 1-9spd derailleur:
If we would want to shift to the biggest cog we would go to the 1st gear, and if we would want to shift to the smallest cog we would go the the 9th gear. BUT that's not the case in my rear derailleur. I could only go to the 2nd smallest cog, and if I would want to shift to the biggest could I would only have to shift 8 times, this means that I would have 1 more shif... Read more >>
i dont know whats really going on but when i was riding my $300 swiss mountain bike i took a brake then got on and tried to peddle. it spawn around w/o catching the back tire. i checked to see if the chain was on, it was. i was having very slow reaction with the front gears with alot of noise before this. i have not used this bike no more then 4-6 times.
if anyone can help thanks. if i can repair it my self i would rather do that since i dont have cash for a repair person..
(but i did notice it started to catch when i go down the drive way (going somewhat speed... Read more >>
I'm a real novice at this so please make allowances! I was having trouble (front derailleur) shifting up from first to second. When I flicked the shift lever into 2nd, the cage would move across seemingly correctly, but the chain would struggle, make a lot of noise and refuse to shift up. If I pushed the shift lever over a little more - towards 3rd - and held it for a couple of seconds, the chain would move up on to 2nd position and stay there OK. I tried to correct this by increasing the tension a little on the shift wire. The result of that was that it shifts up to 2nd correctly, but wo... Read more >>