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 loweredge of the outer cage directly over the largest ring.
Here, we'll pull the shifteror cable to line up these two planes.
The closest gap between the teeth and theadder 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 teethof 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 issuesat the same time.
The outer cage of the front derailleur should beparallel 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 allowboth rotation and height adjustment.
However, before making adjustmentsto the clamp style derailleurs, a tip is to make note ofwhere the clamp is on the tube.
Loosen the mounting boltand move it up or down as needed.
Keep in mind also any changes needed in rotation.
Secure the mountingbolt and inspect the cage.
This braze-on style is found on road bikes, and alsoallows for both height and rotation adjustments.
The high direct mount systems allow forlimited 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 frommoving too far inward and too far outward.
When adjusting limit screwsthe idea is to view the cage and the chain and adjust so the gaps betweenthem are as small as possible, but without chain rub, and with goodshifting.
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 thechain to inner cage gap gets smaller and smaller.
Again, we will be turning theL 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 backwhere 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 smallincrements 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 outone 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 similarin concept to the L limit – However, here we are looking for a small gap betweenthe outer cage and chain.
A large gap increases the chance the chain willdrop off the largest ring during a shift.
Setting the H limit can be confusing because the spring in the derailleur bodyis 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 chainto the smallest rear cog.
Note how this also movesthe 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 counterclockwiseand 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 coupleof turns.
return the shifter to the inward positionand pedal to get the chain under the smallest ring, which matches the shift lever position to theposition 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 makethe 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 usour limit screw is indeed too loose.
We will tighten the H limit screw to reducethis 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 haveachieved a small gap – roughly 1 millimeter.
Now turn the crank to ensure the chaindoesn't rub – as some chain rings have wobble.
Continue to apply constant pressure to the shifter.
Test the H limit setting by shifting to thenext smallest ring, and then back outward.
Press fully on the shifter duringthe shift to simulate good cable settings.
Pushing on the lever isolates thecable setting from the limit setting.
If the shift seemed slow, or the derailleur isunable 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 turnand try the shift again The idea of index shifting is to put thecage in the correct position relative to the chainrings.
This is done by adjusting the barrel adjuster.
Some lever systems may have twoor three positions.
Others have multiple clicks.
The process is the same.
For systems with index shiftersbut no barrel adjusters, the adjustment is made by shorteningand 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 linkageis 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 barreladjuster clockwise to effectively lengthen the cable.
Push on the lever againand repeat until there is slight movement.
Once you have movement, turn the barreladjuster 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-largecombinations, the chain is rubbing the cage, making an adjustment to stop thiswould 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 combinationsthat have a similar gear ratio.
There are some models of shiftersthat use a trim feature.
These are half settings thatslightly move the cage.
As the chain moves inward or outwardas you shift the rear cog, the chain also moves left and rightat the front cage, and can end up rubbing.
Trim allows you to move the cage over a small amountto 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 tofront 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 bitbetween the front derailleur cage and result in a rub when ridingin the largest chainring.
If this happens, you might considerbringing out the cage slightly by adjusting the limit screwand barrel adjuster But to some extent, this is part of the limitation ofthe components.
If you've gone through the process in this videoand are still having problems, check out our videounder 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.
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That's it – we'll see you on our next repair help video.