I have dual-pivot brakes on my road bike, and the other day I started to hear the brake rubbing against the rim. I was towards the end of a group ride on a new route and didn't want to stop for fear of being dropped, so I kept going and the sound kept getting worse. When we finished and I saw that the brakes weren't even close to being centered, so I whipped out my multi tool, tightened the centering screw, and though the problem was solved.
The next night I was out riding and started to hear the pad rubbing again. I stopped to check the brakes and found that they were off center again. I checked the centering screw and it had worked itself loose, so I retightened it and was back on my way. It keeps happening, and now part of my pre-ride ritual is to check the brake alignment. I'm sure there's a way to fix this, but I just don't know how... Any help would be greatly appreciated.
There's a special Loctite brand thread locker called 245 BLUE. It has the ability to lock a fastener and not require heat to break it back loose. The thing that separates it from regular Loctite Blue is that after you have broken the bolt loose it will remain hard to turn until you pull it out. I haven't tried it on a front brake yet but it just might be exactly what you need for this situation. You should be able to get it at Advance Auto Parts.