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Practice English Speaking&Listening with: How to Adjust a Front Derailleur

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The majority of front shifting problems can be solved with some basic adjustments.

In this video we'll show you how to properly set up and adjust your front derailleur.

Calvin Jones here, Park Tool Company.

Before we jump right in, let's get an overview of what we're going to do.

We'll start by inspecting the height and alignment of the derailleur cage.

Once these look good, we will check the limit screw adjustment.

Next, we'll check the cable for the index setting, if that is applicable to your system.

For an overview of how a front derailleur works, watch this video

as it will make the adjustment process even more intutive and easier to follow.

Now let's walk through the process.

Begin by inspecting the two basic variables of derailleur mounting:

Cage height over the chainrings, and cage rotation relative to the chainrings.

The height should be checked with the lower edge of the outer cage directly over the largest ring.

Here, we'll pull the shifter or cable to line up these two planes.

The closest gap between the teeth and the adder cage should be two to three millimeters.

Use a hex wrench as a gauge.

When the cage is set too high, you risk the chance of the chain falling off the largest ring when you shift.

If the cage is too low, it may rub against the teeth of the largest ring, or even the next ring down.

If the height needs adjusting, stop and also inspect cage rotation.

This way you can make changes to both issues at the same time.

The outer cage of the front derailleur should be parallel with the chain ring.

This example is good rotation.

But here, the cage end is too far outward and the derailleur body should be rotated clockwise slightly.

here the cage tail is too far inward and the body needs to be rotated counterclockwise.

Manufacturers have different mounting systems.

Clamp style derailleurs allow both rotation and height adjustment.

However, before making adjustments to the clamp style derailleurs,

a tip is to make note of where the clamp is on the tube.

Loosen the mounting bolt and move it up or down as needed.

Keep in mind also any changes needed in rotation.

Secure the mounting bolt and inspect the cage.

This braze-on style is found on road bikes, and also allows for both height and rotation adjustments.

The high direct mount systems allow for limited height adjustments

Similar to the high direct mount system, the E2 system has no independent rotational adjustment

but does allow for height adjustment.

After derailleur mounting has been inspected and adjusted if necessary,

move on to setting the limit screws.

The limit screws stop the derailleur from moving too far inward and too far outward.

When adjusting limit screws the idea is to view the cage and the chain

and adjust so the gaps between them are as small as possible,

but without chain rub, and with good shifting.

we will start by adjusting the L screw. Shift the front derailleur to the smallest ring.

If the limit screws are not marked, pick one and turn it while watching the cage.

The L screw will cause some cage motion.

Shift the rear derailleur to the largest rear sprocket.

As the rear derailleur shifts, notice the chain to inner cage gap gets smaller and smaller.

Again, we will be turning the L limit screw to adjust this gap,

making it as small as possible without chain rub.

Next, we need to check the shifting cable.

A taut cable can create a false inner limit.

This cable is taut, so we turn the barrel adjuster clockwise one or two revolutions to slacken it.

Don't worry, we'll bring it back where it needs to be later.

Sight from above and slowly spin the crank.

Tighten the L screw to make this gap smaller and smaller until the chain is rubbing against the cage.

Now loosen the L screw in small increments until there is no more rub.

At this point we need to test the L limit.

If you turned the barrel adjuster clockwise, turn it back out counterclockwise.

Shift outward one ring and back to the smallest ring.

If the chain shifts back adequately fast, the L screw setting is done.

We're not yet concerned how it shifts outward -

only how it shifts back inward to the smallest sprocket.

If there's a noticeable delay in getting the chain to drop down to the smallest ring,

turn the L screw out one quarter turn and try the shift again.

The idea here is to have the smallest chain-to-cage gap that you can get away with,

but still have good shifting.

This is because a large gap increases the chance the chain will drop off the smallest ring during the shift.

The H limit screw setting is similar in concept to the L limit -

However, here we are looking for a small gap between the outer cage and chain.

A large gap increases the chance the chain will drop off the largest ring during a shift.

Setting the H limit can be confusing

because the spring in the derailleur body is constantly pulling the derailleur inward.

So in order to test our outer limit screw adjustment,

we will need to use our shift levers to apply constant outward pressure.

The first step is to shift the chain to the smallest rear cog.

Note how this also moves the chain outward at the front.

Shift to the largest front chainring.

If the chain will not make the shift at all, the cable is extremely slack.

Turn the barrel adjuster counterclockwise and try the shift again.

If you ran out of turns at the barrel adjuster, carefully rethread it back in.

Turn it fully in and back out a couple of turns.

return the shifter to the inward position and pedal to get the chain under the smallest ring,

which matches the shift lever position to the position of the derailleur.

you will need to shorten the cable at the pinch bolt.

If it still didn't make the shift, the H limit screw maybe too tight.

Try turning the screw counterclockwise a few turns.

Now that we're on the largest ring, loosen the H limit screw a couple of turns.

We're going to intentionally make the H limit too loose,

Then we'll back it down until it's just right.

Now put extra pressure on the shifter.

There should be a gap here, which tells us our limit screw is indeed too loose.

We will tighten the H limit screw to reduce this gap.

But first, relieve pressure on the shifter.

Tighten no more than a quarter turn.

Apply pressure to check the gap.

Repeat the process until you have achieved a small gap - roughly 1 millimeter.

Now turn the crank to ensure the chain doesn't rub - as some chain rings have wobble.

Continue to apply constant pressure to the shifter.

Test the H limit setting by shifting to the next smallest ring, and then back outward.

Press fully on the shifter during the shift to simulate good cable settings.

Pushing on the lever isolates the cable setting from the limit setting.

If the shift seemed slow, or the derailleur is unable to make the shift,

Even with full pressure on the lever, the limit is too tight.

Loosen no more than one-quarter turn and try the shift again.

If the chain shifts over the largest chainring, or nearly over, the H limit is very loose.

Tighten no more than a quarter turn and try the shift again

The idea of index shifting is to put the cage in the correct position relative to the chainrings.

This is done by adjusting the barrel adjuster.

Some lever systems may have two or three positions.

Others have multiple clicks.

The process is the same.

For systems with index shifters but no barrel adjusters,

the adjustment is made by shortening and lengthening the cable at the pinch bolt.

The chain should be on the smallest rear cog.

Shift to the largest front chainring.

We're going to find the correct cable setting by intentionally introducing movement at the cage

and then systematically removing it.

Movement at the cage tells us that the linkage is not contacting the H limit screw

and when the movement is gone, we know our cable setting is just right.

Push on the shift lever.

If there's no movement at the cage, turn the barrel adjuster clockwise to effectively lengthen the cable.

Push on the lever again and repeat until there is slight movement.

Once you have movement, turn the barrel adjuster counterclockwise one half-turn

and test by pushing on the shift lever.

Repeat this until the cage does not move outward when the shift lever is pushed.

The index setting is now complete.

Note that there are some front and rear gear combinations that manufacturers do not intend to be usable.

For example, on this bike, in the large-to-large combinations, the chain is rubbing the cage,

making an adjustment to stop this would result in rubs and other more usable gears.

On this bike, a small-to-small combination causes a chain rattle against the inner chainring.

There is no adjustment that will stop this.

In these cases, use other gear combinations that have a similar gear ratio.

There are some models of shifters that use a trim feature.

These are half settings that slightly move the cage.

As the chain moves inward or outward as you shift the rear cog,

the chain also moves left and right at the front cage, and can end up rubbing.

Trim allows you to move the cage over a small amount to account for this chain movement.

When there is a trim feature on the shifter, it is built-in by design.

There is no separate adjustment needed.

Those are the basic adjustments to front derailleurs.

The bike still needs to be test-ridden.

Remember that the stresses under use are greater than what we see when the bike is in the repair stand.

For example, when pedaling hard, the frame flexes some under the bottom bracket.

This can cause the chain rings to move a little bit between the front derailleur cage

and result in a rub when riding in the largest chainring.

If this happens, you might consider bringing out the cage slightly

by adjusting the limit screw and barrel adjuster

But to some extent, this is part of the limitation of the components.

If you've gone through the process in this video and are still having problems,

check out our video under advanced troubleshooting.

And finally be sure to check out this video for an overview of all our derailleur and shifting content.

that's it for shifting adjustment.

If you found this helped you, give it a thumbs-up and share it with your friends.

It really does help us provide content for you, and it keeps me locked up here in the studio.

That's it - we'll see you on our next repair help video.

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