Technical Tuesday: How To Set Up Your SRAM Rear Derailleur

How a rear derailleur works is a mystery to a lot of riders, and it's easy to be intimidated by it. One day it could be working perfectly and the next it will have a mind of its own. You take it to your local shop only to have the grumpy wrench wheel it into the back to perform three minutes of voodoo that is apparently a trade secret. He could be making adjustments or he may be sprinkling unicorn droppings on it, who knows? The truth is it's actually a pretty simple job that only requires a couple of tools and some patience to get right. Below you'll find step by step instructions on how to setup your SRAM X9 rear derailleur.

Keep in mind that the same basic principles will apply to other makes and models, although you may find the adjustments in different places.

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Step By Step SRAM Derailleur Setup Instructions

Tools needed: Folding allen key set (or separate 3 mm and 5 mm allen keys), Phillips or flat head screwdriver .


Before you begin adjusting things it is important to be sure that all of your shifting components are in good working order. You could spend the next hour following these instructions, but it will be of no use if you're using bent, damaged, or worn out parts. Take a few minutes to be sure that both your derailleur and derailleur hanger are straight. Do this by standing directly behind your bike and sighting up through your derailleur, everything should be straight and in line. Also, your chain should not be completely worn out and dry, as this will have a detrimental effect on your shifting as well. Likewise, if your cable is rusty and not moving free, all your efforts will be wasted. Once you're happy that everything is in good condition move on to the steps below.

You'll be adjusting three settings during this process: cable tension, limit screws, and B-tension.

Cable Tension

It is exactly as it sounds. The amount of tension on the shift cable controls how much the derailleur moves with each click of the shifter. Too much tension and it will shift past the correct cog as you shift to an easier gear, as well as shift slow in the opposite direction. Too little tension and it will shift slow, or not at all, to a bigger cog, and move too far as you come down to a harder gear. The correct amount of cable tension is a balance that moves the chain up and down over your cassette at just the right amount.

Limit Screws

Think of your limit screws as your derailleur's adjustable stops. They only effect the amount that the derailleur is allowed to move at each extreme of its travel. There are two limit screws, one for the low range (easiest gearing) and one for the high range (hardest gearing), and are labeled accordingly with "H" being for High and "L" for low. The further you dial in the "high" limit screw, the less range your derailleur will have at the high range. If you find that your derailleur is shifting over the top of the largest cog, you'll need to apply more "low" limit until it no longer over shifts. If your shifting is good throughout the middle of your cassette, but is not able to shift to the largest cog, you may have dialed in too much limit. The same applies to the high limit adjustment. If you manage to bend your derailleur or derailleur hanger after you make these adjustments, they will no longer be effective.

B Tension Screw

This lesser known screw adjusts how close the derailleur's upper pulley wheel follows the cassette. If it is too close, the upper pulley and chain will come in contact with the cassette, especially when back pedaling. Too far away and your shifting will be slower than you may like. Certain derailleurs will need more B Tension screw applied to keep them from bumping on large 32 or 34 tooth cogs found on some mountain bike cassettes.

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1. For this process we are going to start from scratch. If your shifting is only slightly out of adjustment you may not need to start from the very beginning. Begin by shifting your SRAM rear derailleur to the smallest cog (least amount of cable tension) and then undo the derailleur's cable anchor bolt in order to release all cable tension. The cable should now be free and have no effect on the shifting. Take note of where the shift cable is clamped in relation to the bolt before you loosen it. Is there a channel or groove where the cable is intended to be clamped? You'll need to know this when the time comes to re clamp the cable.


2. We are going to start by setting the high limit screw to the correct position. This is an important step as some of your other adjustments will be affected by this as well. If your high limit is off, there is a good chance the rest of your adjustments will be as well. To do this, manually move the derailleur with your hand by pushing on the knuckle (not the cage!) and moving the chain up the cassette just as you would if you were shifting to an easier gear. Next, slowly release it and let it come down under it's own spring tension. It should move the chain onto the smallest cog with no hesitation, but at the same time it should not let it go past the cog and and make contact with the frame. Sight from directly behind the smallest cog, the upper pulley wheel and chain should be directly in line with the teeth for the cog.


3. If it is shifting too far and the chain and upper pulley wheel are not lined up with the small cog, or the chain is coming right off and making contact with the frame, you'll need to add more high limit. Turn the high limit screw clockwise half a turn or less and then recheck. Likewise, if the chain is not coming down onto the smallest cog, or hesitating slightly before it does, you'll need to dial out the high limit screw a small amount to let the derailleur have more range.

4. The next step is to correctly adjust your derailleur's low limit screw. This adjustment keeps your rear derailleur from shifting the chain up and over the largest cog and into the spokes. With the shift cable still loose and not clamped down, push gently on the derailleur body (not the cage!) in order to move the chain up to the largest cog just as it would if you were shifting to an easier gear. Do this slowly as if your low limit is not adjusted correctly it will over shift and possibly damage your drive side spokes. You should be able to push the the derailleur body until the chain is on the largest cog. If it doesn't have enough free movement to reach the largest cog, or is doing it slowly, you'll need to dial out the low limit screw by turning it counter clockwise a small amount. If it moves the chain up and over the cog and into the spokes, you'll need to add more low limit by turning the screw clockwise. You should be able to move the derailleur and chain up to the largest cog and feel a firm stop. Again, when sighting from behind, the upper pulley wheel and chain should be directly lined up with the teeth on the largest cog.



5. Now it is time to re clamp your shift cable, but first you should make sure that it is moving free through your shift housing. To do this shift as if you were shifting to the largest cog/easiest gear. Now hold onto the cable end with your hand and shift back down one click at a time. The cable should move freely and not bind at any point. If it does you'll need to replace your cable before continuing. If you are happy with it then move on to the next step.

6. It is very important to make sure that the derailleur and chain are in the smallest cog/hardest gear position before you re clamp your shift cable. Also, be sure to take note of where exactly the cable is supposed to be clamped. Certain models of derailleurs may need to have the cable clamped in different positions. Have a close look and you should be able to see a channel or knurled surface that defines the clamping area. If you position the cable in the wrong spot it will not shift correctly as the cable pull ratio will be off. Before clamping the cable, have the barrel adjuster at the shifter dialed two turns out from full in. With the derailleur in this position, pull the shift cable snug with your hand and clamp it in the correct position under the cable anchor bolt. When doing this be sure to pull all of the slack out of the cable. With practice you'll be able to know just how hard to tug on the cable so that you won't have to make drastic, if any, tension adjustments after it's clamped.


7. Now you're ready to check your shifting and see if any adjustments are needed. While pedaling shift the rear derailleur up one gear at a time towards the largest cog/easiest gear. If it's adjusted correctly, one click of the shifter will move the chain up to the next cog without hesitation and without it over shifting to the next cog. When checking your shifting be sure to shift one gear at a time as it can become confusing if it's out of adjustment and you're doing multiple jumps. The first couple of tries may result in not enough tension, with the symptom being that the derailleur is not able to move enough to bring the chain up to the next largest cog. If this is the case, you'll need to add more tension by dialing the barrel adjuster at the shifter out/counter clockwise. Only turn this adjuster 1/8 to 1/4 turn at each go and then recheck. If you find that it is over shifting and moving the chain too far, you'll need to remove some tension. Do this by dialing the barrel adjuster in/clockwise 1/8 to 1/4 turn and then recheck. Another technique to fine tune your shifting is simply to listen to it. A rear derailleur that is out of adjustment will "tick tick tick" as you pedal, while a properly adjusted one should be nearly silent.


8. Before taking your bike off the stand the last thing to check is the B-Tension screw adjustment. To check this, shift your bike to the largest cog/easiest gear, and pedal forwards and in reverse. The derailleur's upper pulley and chain should not come in contact with the large cog, but be roughly within 5-6 mm of it. If you find that it is rubbing you'll need to add more B-Tension, do this by dialing the screw in/clockwise three to four turns. If it is too far away, your shifting may be slower than it needs to be. If it is too close you could damage the upper pulley wheel as well as not be able to pedal backwards or freewheel correctly.


9. Once you are happy with how your bike is shifting while on the rack be sure to take it for a spin outside before heading up to the mountain. The drive train may react differently during riding because it is under far more load when pedaling with your legs than it was in the rack. You may need to make further adjustments to have it perform optimally, but by using the steps above you should be able to dial it in to perfection.

Technical Tuesday: Chain Wear

One thing that all of our bikes have in common despite their intended discipline, amount of travel, or wheel size, is that they're all powered by a bicycle chain. And from what I've seen, there is a pretty good chance that your chain is either already worn out or is very close to being so. Reading comments from past Technical Tuesdays it is pretty clear that everyone wants to learn how to rebuild their suspension or lace up a wheel, and we will be covering those jobs down the road, but we still have some relatively basic tasks to cover first. It's incredible how many very expensive bikes I've seen that have the latest and greatest parts on them, but have drivetrains that are completely worn out. This is unacceptable in my books! For this Technical Tuesday we are going to show you how to not only properly check for chain wear and some of it's symptoms, but we'll also explain exactly what is happening to your drivetrain as it becomes more and more worn.

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Step by step instructions on checking for chain wear
Tools needed: Chain checker or tape measure.



A modern bicycle chain is made up of inner plates, outer plates, pins, and finally the rollers. The pins are pressed through the outer plates and the rollers and inner plates are free to rotate on them. This allows the chain to circle freely around the chainrings, cogs, and pulley wheels. Two things are happening to your chain as it begins to wear. The most obvious symptom is known as "chain stretch", but the name is a bit misleading. It would be easy to be mistaken in thinking that the inner and outer plates actually stretch with use, but that isn't the case. What is actually happening is the tolerances of the press fit between the chain pins and outer plates is increasing over time and as the small gaps get bigger, the distance between the chain pins get bigger and the total length of the chain increases. The other symptom of a worn chain is rollers that both seem to have shrunk in size, as well as have a lot more room to "float" in the space between the two inner plates. As a chain is used, the rollers slowly get worn down from contact with the cogs and chainrings. As they get smaller, the gap between them obviously increases in size. Further exasperating this issue is how the roller has room to rattle or float within the inner plates. This is caused by wearing down of the inner shoulder that the rollers turn on. So the question is then, how does a worn chain effect the rest of your drivetrain?




A new bicycle chain has a pitch of 1/2" (pitch is the measurement from one chain pin to the next) that matches the same pitch on our chainrings and cogs. The pitch of a chain gets longer as a chain wears. The chain rollers that apply torque to the same spot on each gear tooth as you pedal will slowly wear the teeth as well, although at a slower rate than the chain itself wears. The teeth on the cog or chainring are shaped to work perfectly with the size of the rollers on a half inch chain, as well as being just the right distance apart from their neighbor. Material is slowly removed from the leading edge of the gear teeth as a worn chain applies torque to them, and the ever important distance between each tooth actually gets larger as this happens. This is most evident when you install a new chain on a worn out cassette and discover that it skips under load. Simply put, the new chain will not fit the worn cassette due to the gaps between the teeth now being too large for the new chain and it's 1/2" pitch. There isn't enough engagement to keep it from skipping as you pedal hard. Because a chain wears faster than a cassette, it makes sense to replace your chain multiple times before they become too worn, thereby making your cassette last much longer. The teeth on a worn cassette will have a much more pronounced point to them and look very much like a shark's fin. Chainrings generally wear much slower due to much more contact with the chain which distributes the load over a greater area. Even when a large chainring is badly worn, it may not skip simply due to the amount of wrap that the chain has around it. Middle and small chainrings are another story though...

Measuring a chain with Park's CC-2 chain checker




Measuring a chain with a tape measure

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Don't fret if you don't have a specific chain measuring tool, you can also use a standard tape measure or ruler to figure it out. Just like using a chain checker, you can do this while the chain is still on the bike.

• Line up the tape measure so that the zero inch mark is directly in line with one of the chain pins.

• Holding the tape measure in line with the chain, measure out exactly 6 complete links (A link is a set of both inner and outer plates).

• Because the pitch (distance between each link) of the chain is 1/2", 6 complete links on a new chain will measure exactly out to 12".

• If the chain has wear, the pin will line up slightly past the 12" mark on the tape measure. A general rule of thumb is to replace the
chain once it is over 1/16" past the 12" mark.
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