It may seem that installing derailleurs is as simple as bolting them on – especially if you’ve set up a drivetrain before. However, the designs keep changing. So I’m giving you 10 steps for the front and rear derailleur and chain to follow this week to ensure that your new 11-speed shifting performs perfectly.
This week’s resources
These three articles from Park Tool provide step-by-step front and rear derailleur adjustment and chain installation instructions.
Brief Derailleur Glossary
Braze-on front derailleur: attaches to a mount brazed onto (welded/bonded) or screwed onto the seat tube of the frame
Clamp-on (AKA Band-type) front derailleur: attaches via a wrap-around clamp with a bolt and nut
Rear dropouts: the parts of the frame that the rear wheel attaches to
Derailleur hanger: the part attached beneath the right rear dropout that the rear derailleur is screwed into
Derailleur limit screws: adjusting screws on the front and rear derailleur used for setting the derailleurs’ range of travel to fine-tune shifting (often marked with an H for high and an L for low)
Derailleur chain cage: on the front and rear derailleur, the part that encloses the chain
Derailleur pulleys: on the rear derailleur, the two pulleys held by the cage that the chain rides on
Pulley bolts: the bolts that hold the pulleys in place in the cage
Rear derailleur B tension screw: turned clockwise to ensure that the top derailleur pulley doesn’t bump into the large cogs during shifting
1. Read the front and rear derailleur directions completely. They should be in the box with the derailleurs. If yours came in plastic bags without directions – or with minimal directions (it does happen), visit the brand’s website and search their support section for the instructions and read them there. Or print them. Reading and understanding the directions can save you time and teach you setup steps you didn’t know. It’s likely that there are new adjustments or steps you need to learn.
For example: On some new Shimano front derailleurs there is a tiny little metal “Backup Plate” that you adhere to your seat tube so that the derailleur “Support Bolt” can be tightened against the plate to keep the derailleur from twisting during use. This little part doesn’t look important, yet if you don’t install it correctly, your derailleur won’t work.
2. Check the “braze-on” mount for the front derailleur on the frame. If your front derailleur clamps onto your seat tube with a wrap-around band, you can skip this step. “Braze-on” style derailleurs are most common now. They bolt onto a mount that’s brazed, bonded, riveted or bolted to the seat tube. If yours is bolted on with small allen screws, check that they are tight because the mounts can loosen over time and if the mount isn’t tight, your front derailleur won’t shift correctly or consistently.
3. Mount the front derailleur. Grease the attaching bolt first and place the front derailleur so that the cage is 1.5 to 3mm above the large chainring. Also, make sure that the outer cage plate is parallel to the large chainring. Tighten the derailleur. If there is a small screw at the end of the chain cage, check that it’s tight with the appropriate tool.
4. Now, check the rear derailleur hanger. 11-speed drivetrains benefit from precision derailleur hanger placement since the distance between each shift is so small. To make sure your derailleur hanger is spot on, look for any small allen bolts holding it on and check to make sure they’re tight with the right size allen wrench (on many bicycles the hangers are separate bolt-on pieces for easy replacement).
5. Mount the rear derailleur. Grease the attaching bolt and carefully screw it into the derailleur hanger to mount the rear derailleur. Don’t force the bolt if it doesn’t go right in or you can easily strip the derailleur hanger. Look closely and make sure you’re holding the derailleur in the correct position; the bolt will start to thread when you are. Also, check that the pulley bolts are tight with the right size wrench.
6. Quickly set the rear derailleur limit screws. Look at your derailleur from behind the bike so that you can sight where the pulleys are in relationship to the cassette cogs. If they’re not already there, turn the high gear limit screw counterclockwise until the pulleys move directly beneath the smallest cassette cog. Then push the derailleur in as far as it can go toward the spokes with your fingers and hold it there to check if it stops with the pulleys beneath the largest cog. If not, turn the low gear limit screw the right way to get that to happen.
7. Check the derailleur hanger alignment. The last derailleur check is to sight from behind again to detect any hanger alignment issues. It has to be straight or the shifting won’t work well. If it is straight, an imaginary straight line bisecting the cassette will be parallel to the derailleur pulleys. If the pulleys appear to be angled and not straight up and down, it’s a sign that the hanger has been bent and should be aligned before proceeding. Bicycle shops have special tools for this and it’s not overly expensive. If the hanger is a replaceable type and badly bent, your best option may be to replace it. Check http://wheelsmfg.com/derailleur-hangers.html
8. Clean the new chain. Most new chains come factory coated with a thick anti-corrosive preservative that you should wipe off before installation. Doing that will let your favorite chain lube work optimally and ensure that the chain doesn’t become too grimy too soon. Wipe it clean with a rag moistened with a chain cleaning fluid or isopropyl alcohol. Once it’s on the bike, lube the chain.
9. Read your chain’s instructions. Some chains are designed to work in one direction only. And all chains have special pins or connecting links for joining the chain ends that must be installed correctly. Make sure you understand before moving on to the next step.
10. Size and install the chain. Chains come too long from the factory (with extra links) because you could have any number of different-size chainrings and cassette cogs. You never want to cut a new chain too short. To size yours to length, here’s a handy little online chain length calculator: http://www.machinehead-software.co.uk/bike/chain_length/chainlengthcalc.html
Now that the levers, brakes, derailleurs and chain are on the bike, we can hook everything up by installing the cables. That’s next week!
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