The best thing about riding a mountain bike is running it smoothly and changing gears on challenging terrains. It probably gives you added excitement when your bike shifts and overcomes a road obstacle. Thus, cyclists opt to complete front and rear derailleurs to maximixe the performance of their mountain bikes.
But derailleurs come with a challenge and need some adjustment skills. If you have a front derailleur that toss the chain off the ring, you will want to know how to adjust front derailleur on mountain bike? Check out our guide to adjust the derailleurs on your MTBs.
Table of Contents
Things You Need for This Tutorial
Before anything else, you need to prepare the following to ensure a successful front derailleur setup:
- Repair stand
- Hex wrench (size varies between derailleurs)
Adjusting Front Derailleur on MTB
Step 1: Height adjustment
It is important to use a repair stand for front derailleur adjustment. It will give you a better view of the area and help you position the bike components properly. For this step, it is essential to check the placement of the derailleur cage.
If the cage is too high and above the biggest chainring, you will find it difficult to shift. If it is too low, the derailleur cage could scrape against the rings or may lock up the chain upon shifting.
To adjust a higher derailleur height properly, use a positioning clamp attached to the frame of your bike. Once the clamp is tight, you can adjust the height and angle at the same time.
You should tighten it properly so it can hold the derailleur to the right position. Adjusting the proper height also means positioning the bottom of the cage closer to the teeth of the biggest sprocket.
You need to create a distance of about 2 mm between the teeth and the cage of the derailleur. I recommend using a penny to obtain the right distance. If it is too low, you should look at the outer derailleur plate and make sure the device does not rub on the large chainring.
Step 2: Correcting the angle
The next part to check in your mtb front derailleur is the angle of the front derailleur cage. It must be close and parallel to the chain. If the angle of the front derailleur is too far, shifting will be difficult. To correct the angle, you can use a shifter to obtain the chain onto the outermost chainring as well as the rear sprocket.
Then, check at the chain just found at the top of the ring. In this way, you can easily inspect how the chain passes through the derailleur. The outer cage plate and chain should imitate a parallel direction. Keeping them in a parallel position can reduce the risk of the chain slipping off the outermost ring.
If they are not parallel, the chain tends to over-shift. If there is a gap, you need to rotate the cage and release the tension in the inner wire by shifting it to the inner part of the chainring. To do this, you can loosen the clamp bolt and gradually rotate it in the correct direction.
Step 3: Limit screws adjustment
Another thing you should inspect is the limit screws. The limit screws found at the front derailleur prevent the cage from moving in an inward or even outward direction. The limit screws are marked with an L to prevent moving towards the direction of the smallest chainring and a mark H to stop movements toward the largest chainring.
Step 4: L-screw adjustment
L-screw is the one that controls the inward travel of the front derailleur. It makes the chain to shift only to the smallest ring. If it goes beyond the smallest ring, the chain slips off.
To adjust the L-screw, you have to inspect the wire tension. It must be loose. If the wire is tight, you have to turn the barrel adjuster in a clockwise direction going to the housing. You will find the barrel adjuster in the area where the cable housing normally enters the shift lever.
If you find the barrel adjuster entirely into the housing, you need to loosen the inner wire, pinch the bolt, slacken the tension, and retighten it again.
Step 5: H-screw adjustment
H-screw controls the outward travel of the front derailleur. When adjusting the H-screw, ensure there is enough tension on the inner wire by putting extra pressure on the level. You can also pull the exposed inner wire tight by hand.
It is important to use a cloth or rag when pulling the inner wire to avoid oil or debris coming to your hand. After you adjusted the H-screw, you will notice that the inner wire was re-tensioned and allows smooth shifting.
Step 6: Index setting
After you adjust the limiting screws, you can proceed to index setting. The first thing you should do is shift until the chain is at the middle front of the bicycle chainring and the inner rear sprocket. Then, check the gap between the cage plate and the chain.
The gap should be very thin so the cage cannot rub on the chain. If you find the gap too wide, you must turn the barrel adjuster into a counter-clockwise position. This will increase the tension on the inner wire and narrow down the gap.
After the adjustment, you can check how the derailleur shifts by watching whether the derailleur rubs on any part of the cage. If it does touch the biggest ring, it is important to tighten the H-screw again and the inner wire tension. If the shifting is too slow, you must re-adjust the L-screw or loosen the inner tension wire.
Step 7: Test performance
Once you completed your Shimano front derailleur adjustment, you have to test drive your bicycle by shifting through multiple gears. The chain must not fall off during the shifting. If it does slip, you have to adjust the components again.
It is fine if the chain remains intact but some parts are still rubbing slightly. The most important part is that the chain moves seamlessly and stays on the chain ring. Even with a well-adjusted front derailleur, you can experience a rubbing chain.
Also, check this video to find how to adjust front derailleur on mountain bike:
The front derailleur of a mountain bike is very crucial. A front derailleur that does not shift properly will only make the ride difficult and stressful, so it is important to build up some bike skills and learn about how to adjust front derailleur on a mountain bike correctly.
It may be complicated at first, but with this front derailleur alignment guide, which basically provided you with a complete diagram for the setup, you will find the steps comprehensible and easy to execute. So, check your front derailleur now and apply this step-by-step guide.
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