49. How To Install a Rear Derailleur

Removal and installation of a standard bolt-on rear derailleur.

IMPORTANT: Nuts and bolts on your bike should always be tightened to the manufacturer's specifications.
How To Install a Rear Derailleur
DVD Vol. 2 DVD Volume 2
This video is available on DVD

In this tutorial we'll learn how to replace a standard bolt-on rear derailleur.


For this job you'll need a 5mm hex key for the derailleur's mounting bolt, and a 2.5mm or 3mm hex key for the jockey wheels if you will not be removing the chain to clean or replace it. If you are removing the chain you may need a chain tool depending on your type of chain. You’ll also need wire cutters and a 9 or 10mm metric open end wrench, or a 5 or 6mm hex key to remove and install the rear shift cable. The last thing you’ll need is a phillips (+) screwdriver for adjusting the derailleur's limit screws.

Rear Derailleur Removal

The first step is to shift your chain onto the smallest rear sprocket. Then pull off the shift cable's end cap and loosen the cable pinch bolt. Remove the cable from the derailleur.

Now you'll need to remove the chain from the derailleur. Some chains have a special connector pin that need replacing if removed, so if you don't need to remove the chain for cleaning or replacement you can simply remove the lower jockey wheel and rotate the cage plate to release the chain. If you are removing the chain, disconnect a link and pull the chain through the jockey wheels.

Now you can unthread the derailleur's mounting bolt all the way counter clockwise to remove the derailleur.

Rear Derailleur Installation

Before installing the new rear derailleur, apply some waterproof grease to the mounting bolt. Then thread it part way into the derailleur hanger, and rotate it clockwise to make sure the b-screw or tab is sitting behind the flat on the back of the hanger. Then fully tighten the mounting bolt.

If your chain is still on the bike, undo the bottom jockey wheel and thread the chain over the top pulley. Then re-install the lower jockey wheel. If you have removed the chain, re-route the chain through the jockey wheels and reconnect it. Search the site for tutorials on how to use a chain tool or a quick release chain link.

Rear Derailleur Set-up

Now preset the high-limit (H) screw so the upper jockey wheel is roughly in line with the smallest sprocket when viewed from behind.

Thread the shift cable back into the derailleur, pull it tight and tighten the anchor bolt so the cable flattens. Then find a bare stretch of cable and give it a good pull to make sure the cable is seated and has no slack. Then loosen the cable, pull it tight again and re-tighten it.

Now you'll need to adjust the rear derailleur as shown in previous tutorials. If necessary, trim the cable so there is about 2 inches remaining. Then slide on a cable end cap and crimp it in place.


Discuss this topic in the Derailleur Forums

11/24 Shifter/Cable Slack


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).

11/15 Derailleurs

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 >>

10/28 Derailleur model

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...

10/09 Chain skip

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 >>

09/18 Campagnolo shifter help

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 >>

09/08 Tightening SL-M570 Thumb Lever

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 >>

09/07 Grip Shifter Replacement

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 >>

09/06 Chain Coming off Randomly / Front Derailleur

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 >>

09/06 Rethreading chain - after derailleur dismantling (is it necessary to break the chain?

Novice question probably - so please be kind Smile

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 >>

08/26 Blocked front derailleur?

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 >>

08/08 A Front Derailleur mounting and matching problem.


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 >>

08/05 Shifter wont click

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 >>

08/02 What would you use to replace a Suntour alpha 3000 rear derailleur?

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...

07/29 Derailers and Shifters - Adjustment help needed

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 >>

07/24 Not sure what my problem is!

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 >>

New Thread
How To Install a Rear Derailleur
Repair Guide / Help Forums

Free Email Updates: