There are many reasons you may want to learn how to install front derailleur. It may have stopped shifting through the gears properly, you may want to upgrade to a better derailleur or the old one may be worn out. Whatever the case, front derailleur installation is one of those things that looks quite complicated at first glance, but after you do it once you realize just how easy it is.
This post will take you through the tools and the steps to change a front derailleur. Before that, we’ll take a look at the different types of front derailleurs.
What is a Front Derailleur and Different Types of Front Derailleurs
A derailleur’s job is to change gears. It ‘derails’ the chain and pulls it from one cog or sprocket to the next. The front derailleur is the mechanism that shifts the chain on any bike that has more than one front chainring. It moves the chain between chainrings.
Different types of bikes need different types of derailleurs. For example, road bikes have very simple derailleur mechanisms compared to mountain bike derailleurs which have more complex designs.
A basic derailleur has a cage or box that goes over the chain. This cage is attached to a parallelogram, or linkage system, just like in a rear derailleur. In mechanical derailleurs, the linkage system is moved by a cable while in electric derailleurs it’s moved by a motor.
All derailleurs have limit screws usually marked with an “H” and an “L”. Tightening these screws restricts the cage when you’re cycling.
The term “cable pull” is important when discussing how to change a front derailleur. It refers to the direction from which the cable enters the cage to pull the derailleur. There are 3 types of cable pulls; front pull, bottom pull, and dual pull.
A top pull derailleur is one which the cable is pulled from the top. In bottom pull, the cable is pulled from the bottom. Dual-pull derailleurs were created to make these systems more universal and the cable can be pulled from either the top or the bottom.
Check out How to Install a Rear Derailleur
What Can Damage a Front Derailleur?
There are several reasons why front derailleurs break:
- Over-shifting into the spokes. This usually happens when the low limit screw isn’t properly set and the derailleur moves beyond the largest cog.
- If the hanger bends because of an accident, especially if the bike falls on its right side.
- If the front derailleur is built out of cheap materials or using poor workmanship. If any part of the derailleur is weak it will break even from mild vibrations when you ride over rough terrain.
- Wear, tear, and age are the most common cause for front derailleur breakdown.
- When debris gets caught between the chain and the derailleur it can cause cracks and breakage.
Front Derailleur Maintenance
Checking derailleurs regularly is important if you don’t want to have to be new ones often. With proper maintenance, you can get front derailleurs to last a long time, especially if you don’t use your bike every day and don’t commute over extreme terrain.
All it takes is regular inspection. The easiest way to tell whether your front derailleur has a problem is if it’s making unusual noises when you shift gears. If it’s louder than usual there’s a good chance you need a new front derailleur.
Here’s what else you should look out for:
- The chain shouldn’t come off.
- The chain and the chainring should line up properly (the chain rubs against the chainring).
- Make sure that the derailleur cage isn’t rubbing against the crank arm.
- There shouldn’t be any debris in the cage and anywhere around the front derailleur.
Installing a Front Derailleur: What Tools Do You Need?
To successfully install a front derailleur you need the following tools:
- Derailleur screw driver
- 5mm Hex Key
- A set of Allen keys
- A chain break tool
- A bike repair stand
- High quality lubricant for the chain, the gear and the crank
- Wire cutters
Front Derailleur Installation – 5 Simple Steps
Step 1: Remove the old front derailleur
To do this you need to remove the chain from the first link. Shift it to the smallest front chainring. Pull off the end cap and loosen the pinch bolt. Take the cable off the derailleur.
Now you can remove the chain from the derailleur. Check if the chain has a special connector pin (some do). If it does you’ll need to replace it once done. However, this step isn’t always necessary.
To remove most types of derailleurs, undo the tail screw, open the cage and release the chain. Rest it on the bottom bracket shell.
Step 2: Install the new front derailleur
Before you install the new derailleur, you need to apply waterproof grease on the mounting bolt. Using a clamp, tighten the bolt just enough to keep it securely in place – you should be able to move it easily with your fingers.
Step 3: Adjust derailleur height and angle
Derailleur height matters because if it’s too far above the large chainring it will over-shift. Too low and it will scrape against the chainrings or jam the chain when you shift gears.
The bottom edge of the cage should be about 2mm above the top teeth of the large chainring. For the right angle, rotate the derailleur until the cage comes parallel with the chainrings. Now tighten the mounting bolt completely.
Step 4: Replace the chain
If you had removed the chain completely, re-route it through the cage and reconnect it. The chain tool comes in handy for this step. If you hadn’t taken it off completely, undo the tail screw on the cage and pull the chain through. Once it’s in place tighten the tail screw.
Step 5: Set up the new front derailleur
To do this, preset the “L” screw so that when viewed from above, the small chainring appears halfway between the derailleur cage.
Then thread the shift cable back onto the derailleur and tighten it. Tighten the anchor bolt so that the cable lies flat. It shouldn’t have any slack. Loosen it again, pull it tight and tighten it a second time.
You may need to trim the cable using the wire cutters. You need about 2 inches of cable. Once done replace the cable end cap and crimp it into position.
Check out Tips on How to Clean a Chain on a Bike
Winding up on How to Install Front Derailleur
All this may sound awfully complicated especially if you’re not DIY-oriented. Front derailleurs are not cheap, so if you don’t feel you can go through the steps yourself it’s best to look for a local bike mechanic who does front derailleur installation.
Remember, when it comes to derailleurs quality matters. If you buy a cheap one you’ll have to replace it sooner or later. It makes sense to invest in a high-quality front derailleur that costs more and lasts longer.
Regular bike maintenance goes a long way in ensuring that mechanisms like derailleurs last longer. Clean and lube your bike regularly and use a high-quality lubricant that protects the parts. You can read more about bike chain maintenance here.