Front Mech problems

super_claret

Hi, newbie here.

I'm having problems getting the front mech to shift down properly (from large to middle). It shifts up OK from small, middle to large but when I try shifting back to the middle ring, nothing happens, but when I shift a second time the derailler shifts to the small ring.

I've fitted a new cable and outers and still the same problem! Any ideas?

Cheers, Mark

scotttomo

Have you tried twiddlling (technical term ) the barrel adjuster on the shifter?

Drfabulous0

Ditch it, you don't need it. Figure out what size chainring will suit you best, (I use 38T on a mountain bike) and do away with the horrible piece of kit.

If you really want it first check it is positioned correctly. Stock bikes almost always come with the front mech positioned too high above the chainrings for it to work properly. Once the mech is just a few mm above the big ring adjust the stop screw marked L until the mech will pull the chain all the way down to the little ring but stop short of pulling it right off. Sometimes it works better with the back of the mech angled slightly in towards the center of the bike than straight in line with the chain, you will have to experiment with this but make sure the back of the mech isn't too close to your tyre.

Don't expect the front mech to shift into 1 while the rear mech is at 8, this is not a gear you should be rididng in and if you lokk closely at the shape of the front mech you will see that the chain in this position won't engage with the bulge on the mech that pushes the chain down, only change down at the front when you are in a middle to low gear at the back.

Check your riding technique, you need to back off the pedalling for a moment while you change down. The tension in the deraileur spring is not enough to move the chain down if you are cranking up a hill as hard as you can, you need to move your pedals slower than your momentum for 1 revolution when you shift.