Had an email from a guy yesterday telling of his recent
success tuning his rear derailleur, following my recent post on the topic.
However, his bike also has a front derailleur...
So, with
sincere apologies for neglecting the front end, here is how to whip those
doubles and triples into shape.
The
procedures and adjustments are very similar to the rear but, we do have one
rather important extra step. Unlike the rear, there is not just one single point of simple
attachment. We have to set the height and angle using our own judgment.
So, what we
are looking for is clearance of the cage of the derailleur as it swings over
the chain rings, while still keeping it low. A gap of about 1mm between the top
of the big ring and the bottom of the outer cage plate is ideal; manually pivot
the cage out to get a look at the gap.
Next we
need to set the angle. As you look down onto the chain rings the cage of the derailleur
needs to run parallel with the rings.
Now you have
your derailleur mounted correctly we can set the limit screws. We start on the
low limit screw first.
Change gear
at the rear to the high gear, small cog. Here is where it gets a little tricky.
You now have to manually swing the front derailleur out while turning the crank
to shift into the high gear, big ring. It might take you a couple of tries, the
spring on the derailleur is pretty tough. Once you get it pushed out to its
stop, adjust the High limit screw to get clearance between the chain and outer
cage plate of 1mm, when you are happy, release hold of the derailleur and cycle
the chain back to the small ring. Attach the cable making sure that the shifter
is set on the low gear or number 1.
Try it out.
If you have a slack in the cable, just take it out using quarter turns on the
barrel adjuster, until it works perfectly.
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