If cycling is supposed to be zen, then a noisy bike is punk rock, or maybe a punk rocker. Not only can both bikes and punk rockers be obnoxiously loud, but the growing popularity of carbon fiber bicycle components combined with the increasing creativity of body piercers is causing them to rapidly converge in terms of metal content, and since most punk rockers keep to a strict diet of tattoos and cigarettes, their weights often converge as well. (how else does one get into those pants?)
Rock or rocker, a rattly bike is sure to clatter along out of tune, all around the beat and beg you to put it out of it's misery before too many people get to hear it. For most creaks and rattles a little grease and a wrench will go a long way toward making your rides more pleasant, but every once in a while there's a noise you just can't manage to pin down, and no matter how hard you go at your bike with the wrench it just won't give up. My favorite is the water bottle cage braze-on. Not only does a loose braze-on make the bottle cage rattle omni-directionally through your entire frame, but the rattle also changes rhythm and pitch every time you have a drink, making it as elusive as it is grating. Even if you do manage to realize what's making the racket and take an allen wrench to it, all the tightening in the world can't help you. In every way, the rattly bottle cage is the ultimate zen-killer, and this is Bodhidharma:
Long story short, most bottle cage braze-ons on modern bicycles are not braze-ons at all, but Riv-Nuts, which are a sort of blind faced rivet. In order to tighten the rivet, you have to push on the face while pulling up on the threads at the back without spinning the entire thing in the hole. The gadget above -- made out of a long bottle cage screw, a nut and a washer or two -- is designed to do exactly that.
To use it, thread the nut all the way onto the BC screw, then thread the BC screw as far as you can into the riv-nut. While holding the BC screw in place with an allen wrench, use an open-end wrench to tighten the nut down onto the riv-nut. You want to tighten the nut firmly, but don't wail on it too hard or you will strip it out. IMPORTANT: To remove your tool, hold the allen wrench still and back off the nut until you can turn the BC screw with your fingers. If you try to remove the screw with the nut still tight you might re-loosen the riv-nut.
Ride happy and rattle free.