How to Install a Rear Derailleur
Removal and installation of a standard bolt-on rear derailleur.
- How to Adjust Your Rear Derailleur
- How to Align a Rear Derailleur Hanger
- How to Overhaul a Jockey Wheel
- How to Replace an Inner Shift Cable
- How To Install a Front Derailleur
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.
- Park Tool HXS-1.2 Hex Wrench Set
- Park Tool Wrench Combo Set
- Park Tool SD-Set Shop Screwdrivers
- Shimano TL-CT10 Cable Cutter
- Park Tool SK-3 Starter Mechanic Tool Kit
- Park Tool PK-3 Professional Tool Kit
Discuss this topic in the Derailleur Forums
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I've tried searching for YouTube assistance but to no avail. Cycled to the shops this morning and the gears weren't functioning, had a look and something has gone horribly wrong. It's as though the chain is suddenly inches longer than it should be and it isn't holding any tension unless the derailleur sits all the way back (image attached) almost so the chain is touching itself as it travels throu...Read more
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