For touch up or new stripes. I tried it and it works GREAT! I've used these Pilot Metallic Markers for years to label plastic plant markers outside. I wondered if it would help touch up the Gold pinstripes on my Gitane TdF and it did. I tried it on another bike (see photos attached) without the detailing (the silver diamond was factory color) and it went on like a charm.
The good thing is that if you mess up you can wipe it off with WD-40, or the like, and start over. Once dry it won't rub off but you can still remove it with the solvent.
The pen point pumps to get the ink flowing and it follows the lug/tube seam easily. You can even stop and start again.
They come in Gold and Silver and it is much more metallic looking than in the photos. If you decide to try it, get the EXTRA FINE POINT. They are available at most Office Supply and Hobby stores for about $2.50 each. White is now available.
Also, Sharpie has come out with an Oil Based marker in colors. ( I have not tried it )
http://www.sharpie.com/
Jay Dubiel
Halifax, VA USA