Fear of wrenching...

[fidlfreek]

Hey Boise Birder -
I have found these to be great starting points!

http://www.parktool.com/repair/byregion.asp
www.sheldonbrown.com

So, ladies I need a little help to get me past the point where these great sites left off....I am intrepidly attempting a tiny adjustment on my front derailleur and am stuck on a small point. After a recent cleaning I noticed that a little nasty sound on downhills was caused by my chain rubbing in the big ring while in the the outermost gears....

So I know I just need to allow the cage to move slightly farther out from the bike frame when its in the big chainring. (I am using a 3 chainring Shimano 105 on a new Bianchi road bike). From the Park Tool website and the SheldonBrown website I know I need to tighten my H screw like 1/8th of a turn. Tiny. However, the screws aren't marked L and H and I'm way way too scared to test it like the site suggests... And google isn't finding me a handy diagram...

Can someone just tell me which screw is the H? Is there anything else I need to do after I tighten the screw that tiny bit? Am I stupid to try this?

Thanks guys for any suggestions you have!