Originally Posted by lhbernhardt
Usually, the cable doesn't just get clamped as you pull it straight up. Usually, you have to run it *outside* a small flange and then pull it outward and clamp it at the *top* of the bolt. This gives you far more leverage in pulling the derailleur.
Yes, and even bike shop mechanics frequently run the cable under the flange because it "looks" like that's what the flange is made for, but isn't. It's a leverage device.
Here's one of the better links that I've seen describing this:
http://www.hostelshoppe.com/tech_frontderail.php