Alex: Welcome to another GCN Tech home maintenance video.
Today, we're going to show you how to remove and replace your front derailer.
Now, you're only going to need a few basic tools. Again, you're going to need a 4mm Allen key,
a 5mm Allen key, a 2mm, and you're going to need the relevant tools to remove your
chains such as the chain tool or chain pliers. You're also going to need a set
of normal pliers to remove the cable end here. Our first job is going to be to shift into the
small chainring, and that will put the mech in the position ready for us to remove the cable end here
and also use our former Allen key to remove the cable from the front derailer.
First off, we're going to need to get our pliers, remove the cable end like so, give me a pull like
that. Put that to the side. Now that we've got the cable end removed, we can look to remove this
plastic cap here and guide that off of the cable. I lift that up like so and then guide that off of
the cable. Set that to the side nice and safe. From here, we can pull the cable out
like this, ready to use our 4mm Allen key like so, to undo the cable tension.
Now we've got to this point, we can remove the cable from there and set that to the side out
of the way, ready to be used later on. Now that we've got the cable removed and out of the way,
we can look to now take the chain off, get that tucked out of the way nice and safe.
Then that will be the last step of removing the actual derailer from the bike. Using our quick
link pliers, you can slide those in here. If you're fortunate enough to have a quick link,
squeeze them together like so, and that will enable us to break the chain.
Now that we've got the quick links removed, we can carefully remove the chain from the bike,
making sure we try our best not to drag the chain up against the frame like so.
Guide it around the rear cassette and through the rear derailer.
Now that we've got the chain off, we can set that to the side on the workbench.
The cable is no longer attached, so that's free. We can now use the 5mm Allen key to go in at the
front here and loosen the main bolt that holds the derailleur to the frame. Be a little bit tight,
like so. Then we can use the other end of the Allen key, holding the derailleur to the frame,
and then remove this bolt like so making sure not to lose this curved washer.
Now that we've got the front derailer removed, it's a case of looking to
refit it back again using the small bolt here with the curved washer attached.
We can take the front derailer, guide it into this frame here, and then put the bolt back in as so.
Now that we've got the derailleur loosely fitted to the bike, it's a case of correctly
setting the height and making sure the cage is in line with the chainrings.
Now, this type is a brazen type which uses a bracket that's attached to the frame. The
other type you might have is a clamp type which uses a clamp attached to the derailer,
which goes all the way around the tube of the frame. They're not quite as common anymore,
but they're still out there. Here's where we can use our 2mm Allen key. Let's go through the center
of the derailer onto that support bolt. Here we can align the derailer cage with the chainrings
before we set the height correctly. We turn it in, check it's lined up nicely
like so, and that can stay there until we set the height using the 5mm Allen key.
Using our5 mm Allen key, we can go in, look to set the height of the derailer to make sure it
clears the chainrings hoping for about a 1 to 2-millimeter gap for a nice smooth shifting.
Now we've gotten the derailer correctly attached to the frame, the height set correctly,
the support bar with the back has been set correctly to ensure the cage is parallel
with the chainrings. We can now go ahead and look to refill the cable back to the derailer.
To refit the cable, it's a case of guiding it through the back of the derailer
and then here lining it up through, carefully guiding it underneath the pinch bolt cover. Now
that we've got a bit of tension onto the cable, we can use the 4mm Allen key to tighten that up
nice and secure. Now the cable is attached, we can look to refit the chain, and that will move
us onto one of the final steps of setting the high and low limit screws. To refit the chain,
we can just guide it through the frame carefully here across towards the chainrings like so,
carefully pedal that round. Once that's there,
we can now move the chain around the cassette, guide all the way round onto the pulley wheels,
and then through the pulley wheels, down the rear derailer, bringing that all the
way around. We can use our quick links here. to refit the chain back together.
I'm using the pliers
like so. Now that we've got the chain refitted correctly,
we're going to look to set the low limit screw on the front derailleur first.
To do that we're going to need to shift all the way into the largest sprocket on the back,
and that will enable us to look to set this correctly at the front.
Now that we've got the bike and the largest sprocket at the back here,
and the smallest chainring at the front, now we can use our 2mm Allen key to look to
go in and set this small screw here labelled with the L. Now what we're trying to achieve
is carefully adjust this so that the inside edge of the derailleur cage just misses the chain when
it's peddling. We can check that, peddle that. You can see there about as close as we can get
it without causing it to rub. Now that we've got the low limit screw set, we're going to have
to shift into the big chainring and all the way down into the smallest sprocket on the cassette.
That will enable us to set the high limit screw correctly using our 2mm Allen key.
Now that we've shifted into the smallest sprocket on the cassette and the largest
chainring on the front, we can use our 2mm Allen key to look to set the high limit screw.
Similar to when we're setting the low limit screw, we're making sure the derailleur cage
is nice and close, but not touching the chain on the outside edge here.
Now that we've got the high limit screw set, we can check that there's a nice, small gap
between the chain and the outside edge of the derailleur cage here. Close, but not touching.
Now we've got the high and low limit screws set, we can now check to see if the front
derailleur operates correctly and add any cable tension if we need to using our 2mm Allen key
on this small little bolt here. Turning it to add or remove tension to the cable. Now that we've got
the cable tension set correctly, we can look to tidy the cable up, guide it all the way around,
refit our small plastic cover from earlier, and then make sure we've got a nice, tidy setup.
There you have it, the front derailleur replaced and set
up. It's worth just running through the gears to make sure they work correctly.
I hope you've enjoyed this video. If you have, let us know in the comments section below,
and most importantly give us a thumbs up. [00:07:49] [END OF AUDIO]