The front derailleur is an essential part of your mountain bike, responsible for shifting the chain. In case it mal-adjust, then it becomes challenging to shift the gear. I understand the frustration, and that’s why I want to share with you how to adjust front derailleur on mountain bike.
Here is how to adjust front derailleur on mountain bike in these 6 simple steps:
- Adjusting the front derailleur height
- Adjusting the front derailleur angle
- Checking the L & H limit screws
- Adjusting the low-gear limit
- Adjusting the cable tension
- Repositioning the high-gear limit
I’ll explain all the six steps for front derailleur adjustment in detail to help you do it on your own. So, I trust you’ll find the tips easy to employ and useful.
But before anything, let’s look at the tools you need for the job. Generally, you need these two tools before you can start repositioning your out of place front derailleur:
- Wrench for tightening the clamp
- Screwdriver for turning the L & H screw
How To Adjust Front Derailleur On Mountain Bike in 6 Steps
Here are the steps for repositioning your MTB’s front derailleur:
Step 1 – Adjusting the Derailleur Height
Before anything, the derailleur must be at the right height. You can do that by tightening the clamp.
The mountain bike front derailleur should sit about 1-3mm above the chainring. If it sits more than 3mm above the chainring, you may have a problem shifting the gears.
Likewise, if the derailleur sits less than 1mm above the chainring, the two may rub against each other when shifting. So, try to keep the distance 1-3mmm when adjusting the derailleur height.
Once you are done adjusting the derailleur height, take a step back and check the derailleur cage to ensure it is properly aligned.
Alternatively, shift towards the middle-front ring and then check if the front derailleur cage is sitting correctly. If it’s not, consider going back to a lower gear before readjusting the height using the positional clamp.
Step 2 – Adjusting Front Derailleur Angle
The chainring and the derailleur cage must be nearly parallel to each other. If they aren’t, then it’s time to adjust them.
If the derailleur needs adjusting, consider doing the following:
- Shift-down to the inner chainring level to effectively relieve the inner wire tension
- Loosen the bolts on the clamp before rotating the derailleur to its perfect position
- Since you’ve already adjusted the derailleur height in step 1, don’t interfere with it in this step
- Shift-back to the outer chainring before observing the alignment
- Repeat the entire process until the chainring and the derailleur cage are parallel to each other
Step 3 – Checking the Limit Screws
The work of the limit screws is to prevent the front derailleur cage from moving inwards and outwards. These screws are labeled H and L.
While the H screw stops the cage from going past the outer/biggest chainring, the L screw prevents it from going beyond the inner-smallest chainring.
Remember to check for the labeling of the limit screws. If they aren’t labeled, you’ll have to test them to distinguish them.
You can do that by picking one of the two unlabeled screws and turning it clockwise and then anticlockwise.
If the derailleur shifts, the screw is an L-screw, but it’s an H-screw if it doesn’t. Remember to mark the screws after identifying them. You’ll need them to perform the next steps on how to adjust a front derailleur.
Step 4 – Adjusting the Low-Gear Limit
This step requires you to move the chain to the biggest rear sprocket and shift the small sprocket to the front.
Use the screwdriver to adjust the L screw until the inner derailleur moves closer to the chain. However, ensure the two don’t touch.
Step 5 – Adjusting the Cable Tension
It’s now time to attach the derailleur to the anchoring bolt. While at it, confirm that the shifter is at the lowest gear level.
You need to loosen up the derailleur cable before you can retighten it together with the anchor bolt.
Step 6 – Repositioning the High-Gear Limit
Now that you’ve already adjusted the low gear limit, what remains is the high-gear limit. It’s the last step in adjusting front derailleur mountain bike.
To reposition it, shift the outer (bigger) chainring into the front and the smallest to the rear.
Use the screwdriver to smoothly turn the H screw until the chain and the outer derailleur cage moves close to each other. They shouldn’t touch each, remember.
Once you succeed at adjusting the high-gear limit, it will guarantee that the chain does not fall out of place.
How To Make Sure The Adjusted Front Derailleur Works
After following the steps on’ how to adjust front derailleur’, you’ve to ensure the derailleur works. Here’s how to go about it:
- Test the Derailleur
Here, you’ll need to shift the entire gear range of your MTB. That should make the front derailleur to move into the biggest and smallest chainring without rubbing against the chainring.
If the derailleur rubs against the chain, the installation wasn’t a success.
- Test the Barrel Adjuster
Try moving the barrel adjuster counterclockwise to improve the cable tension. That’ll help to move the derailleur into the outer chainring.
If you can push the front derailleur outward, it’s likelier that the cable tension is not in position. So, you have to readjust the barrel adjuster to correct it.
- Ride Your MTB Normally
If the above tips sound too technical, ride the bike customarily after completing the six steps discussed above.
If something feels odd when shifting, then you may have to redo the process or take the bike to a mechanic.
What Is The Best Front Derailleur For Mountain Bike?
If you are looking to upgrade your MTB front derailleur, I recommend the following options:
- Shimano Tourney AO73 Front Derailleur – Best for double and triple 7-speed drivetrains
- Shimano FD M310 Altus Front Derailleur – Best for double and triple 8-speed drivetrains
Concluding Thoughts On How To Adjust Front Derailleur On Mountain Bike
Now you know how to adjust front derailleur on mountain bike. So, if it ever mal-adjust, take out a wrench and screwdriver and employ the above six steps to readjust it.
Frequently Asked Questions
How do you adjust a Shimano front derailleur on a mountain bike?
Adjusting the Shimano front derailleur on your beloved mountain bike can at first appear to be a daunting prospect, but with a little patience, it’s a task you’re fully capable of accomplishing. There are a few key steps to this adjustment process that I can vouch for from experience. The first step involves loosening the derailleur’s securing bolt to allow for the repositioning of the derailleur. On the same note, ensure the derailleur is positioned correctly, with the outer plate over largest chainring of your bike, and the bottom of the derailleur sitting approximately 2mm over the top of the teeth on the large chainring. Tighten up the securing bolt and then you can move on to adjusting the ‘H’ and ‘L’ limit screws to help avoid the chain from coming off on the high and low gears respectively. Remember that minor adjustments can make the world of difference, so take your time, and adjust in small increments rather than large ones.
How do you adjust a mountain bike derailleur?
In my years of adjusting derailleurs on mountain bikes, I’ve found that the process typically involves altering the high / low limit screws as well as the derailleur’s cable tension. This determines the derailleur’s range of motion and shifting precision. You can find the limit screws on the body of the derailleur with usually ‘H’ for High (outermost gear) and ‘L’ for Low (innermost gear) labels. Adjustments to these screws control how far the derailleur can move. If it’s done correctly, it can help improve flawless gear shifting and prevent the chain from either dropping off the smallest gear onto the bottom of the bike or crashing into the frame by overpassing the largest gear. You can also make fine-tuning adjustments to the cable tension, usually located on the shifting lever incrementally until your desire shifting performance is achieved. I always advise doing this process carefully and patiently for the most efficient results.
How high should front derailleur be on mountain bike?
In terms of the proper height positioning for your front derailleur, it ought to be located in such a way that when positioned over the outermost chainring, the ‘cage’ of the derailleur which you can recognize as the lengthy, curved part that the chain travels through, should sit roughly 2mm above the tips of the teeth on the chainring. This measurement is observed through a sideline viewpoint. In my biking experience, I’ve learned that the derailleur height is paramount for reliable and smooth shifting. If the derailleur is too low, it could drag on the chainring during shifts, causing premature wear and potentially damaging both elements. If it’s too high, it will not effectively guide the chain from one chainring to the next.
What do the screws on a front derailleur do?
The front derailleur, akin to the rear derailleur, typically consists of screws labeled with an ‘H’ and an ‘L’. These screws embody crucial roles in the performance of the derailleur. They exist primarily to limit the movement of the cage at both ends. It’s a feature particularly useful in ensuring the chain does not overshoot the chainrings by either falling off the smallest or going past the largest one. In my years of experience biking, properly adjusting these screws has prevented countless slipped chains, which especially at high speeds, can be both annoying and dangerous. It’s a simple tweak that makes a noticeable difference on your ride.