Urbanmonk

I am trying to learn how to make some adjustments and changes on my cross bike, so as to not rely completely on my LBS. I will be the only one on the road when there is a breakdown. My question is: how do you adjust the front derailer on a double-ring set-up? It has a Tiagra up front which has two small phillips head screws; vertically, one sits above the other. When the bike shop changed handle bars for a wider set, the adjustments went with the old bars. I live two hours away from the shop, so I am relying on your expertise. Advise, please. Thank you.

Urbanmonk

Retro Grouch 

You don't need to jack with them. The two screws that you are referring to are the limit screws. They limit how far the derailleur will move inward and outward from the frame. Once they are correctly set, they NEVER NEVER EVER have to be moved unless you get either a new derailleur or a new crankset.

If your front derailleur ever worked right, provided nobody has screwed it up, the only adjustment that is ever necessary is cable tension.

The mistake most guys make is to start fiddling with things they don't understand and they pile one misadjustment onto another until their front derailleur shifts so badly that they give up. Don't be that guy!

Urbanmonk

Well, sorry to say, I am that guy now; although I won't give up. When the bike shop made the bar swap, they lost the adjustments--don't know why they didn't check. Anyway, this is where I'm at now. Cable adjustment is all it takes, huh? I'll give it a try. I guess this was my first lesson. A humble thanks.

Urbanmonk

Retro Grouch 

In that case, try this:

1. Disconnect the shift cable from the derailleur. This is important.
2. Adjust the position of the derailleur on the seat tube. The outer derailleur cage should be parallel to the big chainring. The height should be such that the derailleur cage will just miss hitting the big chainring by 2mm.
3. Adjust the low gear limit screw. Without the cable attached, one of those screws in the top of the derailleur will make it move in and out. With the chain on the little ring in front and the biggest cog on the back, adjust that screw so that the inner cage misses the chain by 1mm.
4. Make sure that your shifter is in it's lowest gear position. Now grab your shift cable with your needlenose plier and pull it taut. Anchor it to the derailleur. Be sure that you go the correct way around the anchor bolt.
5. Test shift into various gear combinations. Adjust the cable tension until they come out right. If you are having a hard time making this happen, check the previous steps starting with one.
6. Shift into your big ring on the front and the smallest cog in back. Dial in the other screw on top of your derailleur until the outer derailleur cage is about 1mm from the chain.

You are now qualified to call yourself a bike wrench.

Urbanmonk

Thank you! I am an educator, so I appreciate clarity wherever I see it. You have been a tremendous help. Now, to the bike.

Cheers

tlippy

Retro-------I also turn all the barrell adjusters on the cable (sometimes two) all the way CW, when the cable has been removed. This will give you maximum availale adjustment for the future. If you turn all the barrells fully CW, you don't need to tension the wire with plyers------by hand is sufficient.