Nothing is more frustrating on a bike than gears that just won’t behave.
However, problematic gear shifting doesn’t have to mean a costly trip to your local bike shop. Learning how to adjust derailleurs on a bike is one of the most worthwhile bike maintenance skills a cyclist can learn.
Once you’ve mastered how to adjust a derailleur, you’ll be back on the road (or trail) with silky-smooth shifting again in no time!
In this bike maintenance guide, we’ll be covering:
- Why Do I Need To Know How To Adjust Derailleurs?
- What Equipment Do I Need To Adjust A Derailleur?
- How To Adjust Front Derailleur In 4 Steps
- How To Adjust Rear Derailleur In 3 Steps
- Troubleshooting: What If My Derailleurs Still Aren’t Working Properly?
Let’s dive in!
Why Do I Need To Know How To Adjust Derailleurs?
Before we start speaking about how to adjust your derailleurs properly, it’s important to understand why having your derailleurs working correctly is vital.
Preventing chain slip
If your derailleurs aren’t in line, the chain can easily slip from one gear to another.
Besides being irritating, this can make your feet slip off the pedals, which is especially dangerous when you’re climbing out of the saddle.
Ensuring A Comfortable And Efficient Ride
If your derailleurs are skipping gears and not changing when you need them, it will ruin the ride. You’ll be focusing on your gears not working properly and not enjoying the fun of riding a bike.
Prolonging The Lifespan of Components
If your gears are not working properly, the components of your drivetrain such as your chain and cassette are likely to wear faster.
Keeping your bike in full working condition means you get much more mileage from it.
What Equipment Do I Need To Adjust A Derailleur?
On most geared bikes, you have a front derailleur and a rear derailleur.
In this guide, were going to be telling you how to adjust both. Not all derailleurs are the same, but they do work on the same principles.
Here are the tools we recommend that you have when learning how to adjust derailleurs:
- Bike Stand
- Cleaning Products
- Allen Keys
- Small Screwdriver
We highly recommend you clean the drivetrain thoroughly before you start.
You want to get all the mud off and degrease the chain, derailleurs, chainrings, jockey wheels, and cassette. Not only does it make it cleaner to work on, but it helps you make perfect adjustments without grime bogging it all down.
How To Adjust Front Derailleur In 4 Steps
Step 1: Set the front derailleur height and angle
Looking at the derailleur straight on, you want to ensure the cage sits 2-3 mm above the largest chainring.
Then, looking from above, you want to ensure the cage sits parallel with the largest chainring, as pictured above. This is adjusted on the clamp, which bolts the derailleur to the frame.
Step 2: Adjust The Low-limit screw
Limit screws prevent the derailleur from moving too far inwards and outwards.
First, shift your bike into the smallest ring on the chainset and the largest ring on the rear cassette.
The limit screws are often marked with “H” (high) and “L” (low). If yours are unmarked, the screw closest to the frame is usually the low-limit screw, which limits the movement of the derailleur toward the frame.
By turning the low screw, you will see the cage adjust back and forth. You want the cage to be as close as possible to the back of the chain but without it touching.
Now rotate the pedal and try shifting it up and down the chainrings. It should freely and smoothly shift without the chain falling off the bottom.
Make small adjustments if necessary to get it perfect.
Step 3: Adjust the High-limit screw
Start by shifting your chain to the smallest cog on the rear cassette and into the largest chainring on the front using the shifter.
If the shifter doesn’t take you into the top ring, you might need to tighten the cable.
Using the high screw, you can move the front derailleur back and forth. We recommend getting the chain as close to the derailleur cage as possible without it touching.
Test it by shifting up and down and ensuring it shifts smoothly without the chain falling off or taking a long time to change.
Make small adjustments until perfect.
Step 4: Indexing the Front Derailleur
Finally, the last thing you need to do is index the cable.
This means the derailleur will line up with each cog with each shift. Derailleurs typically have an adjustment screw, or they will have a barrel adjuster on the cable itself.
We need to start by ensuring there’s no slack in the cable, so loosen the cable pinch bolt with the derailleur in the lowest gear and the adjustment screw fully in. Then pull it finger tight and tighten up the cable pinch bolt again.
Now, start turning the pedals and shifting the derailleur up and down.
Keep adding a turn on the barrel adjuster or adjustment screw until the shift is smooth and the chain moves up and down the chainings easily without rubbing.
This can take a few minutes but be patient, and it will become perfect soon enough.
- Need more detail? Check out our Video Guide To Adjusting A Front Derailleur here!
How To Adjust Rear Derailleur In 3 Steps
Step 1: Set the high-limit screw
Start by shifting into the biggest front chainring and the smallest cog on the rear cassette. If it struggles to get there, you should remove some slack from the cable with the barrel adjuster.
One in the bottom gear, you’ll want to go to the barrel adjuster and loosen it. You can do this by screwing it inwards.
Now, turn the H screw in until it starts making a slight noise like it is trying to skip up. At this point, loosen it off until it sounds smooth – and your high-limit screw is set.
Step 2: Indexing the Rear Derailleur
Go to the barrel adjuster and screw it clockwise while in the top (hardest) gear on the shifter. Now, release the cable from the derailleur, pull it finger tight, then secure it again.
Start turning the pedals and click the shifter once as though moving one gear easier on the cassette. It won’t move, but this is fine.
Continue turning the pedals while unscrewing the barrel adjuster half turn at a time until the chain jumps up a gear.
Once it has jumped up, stop turning the barrel adjuster and try going up another gear. If it clicks across to the next gear, continue going up until it gets to the biggest cog.
If it struggles to get to a later cog, you will need to unscrew the adjuster further. Repeat this process until it goes up and down the cassette smoothly and quietly.
Step 3: Set The Low-limit screw
Now the final step; we need to adjust the low-limit screw.
Shift to your smallest chainring on the front and largest cog on the cassette. Tighten the L screw until it jumps into the next cog along, then loosen it off until it drops back into that largest cog.
Now your low-limit screw is set!
Take extra care not to loosen the low-limit screw on the cassette too far. When adjusted improperly, the derailleur can contact the spokes of the wheel, with expensive – and potentially hazardous – consequences.
Troubleshooting: What If My Derailleurs Still Aren’t Working Properly?
Sometimes you can run through this process repeatedly, but something still just isn’t quite right with your shifting.
It could be a variety of different things, so here are the most common issues you might encounter and how to fix them.
#1. Bent derailleur cage
You will struggle to adjust your gears properly if you have a bent derailleur cage. We recommend replacing your derailleur to fix this, as bending it back is almost impossible.
- Check out our Complete Guide To Installing A Rear Derailleur here!
#2. Bent mech hanger (Derailleur Hanger)
On the rear, the derailleur is attached to a mech hanger (or derailleur hanger).
The mech hanger is a cheap sacrificial part made of soft metal, and is specifically designed to bend or break. In a crash or knock, the derailleur hanger will break more easily than the expensive derailleur, helping to prevent damage.
It’s important to check this is straight visually. If not, it can throw off your shifting or even push the derailleur into the spokes. Order a replacement, or head to your local bike shop if you need a helping hand.
#3. Worn or broken cables
If your cables are old, worn, or dirty, you will find your shifting becomes very poor, which can stop the derailleurs from working altogether.
We highly recommend checking these and replacing them when necessary to keep your shifting in top condition.
Now you know how to adjust derailleurs on a bike…
You’re ready to put the knowledge to use!
We hope you enjoyed our guide on how to adjust your derailleurs. It might take a bit of practice to master, but in time it will be very easy and come as second nature.
Before you know it you’ll be adjusting your whole cycling club’s bikes!
