My new single speed came with brazed on bosses/lugs for fenders but not a water bottle cage. So I figure... new bike... I'll drop a few $$$ for a new water bottle. At the bike shop I select a bottle and this hot alloy cage and then ask for oval clamps to mount it on the down tube. Much to my surprise, oval clamp rings don't exist or at least not at my local bike shop. I'm told that I need to mount the cage using rivet nuts. I'm shown that they're used in lieu of braze-ons on aluminum frames. Well that's fine and good for aluminum frames but my frame is double butted 520 chrome-molly steel and the down tube is oval in cross-section. The water bottle cage would be mounted in the middle of the tube where the wall is the thinnest. I'm concerned that two penetrations here would compromise the strength and lead to the frame failing. Am I being paranoid?
Yeh, I had that problem with my wife's bike. Do not drill, there are lots of strap or bolt on bottle holders. There are some that go in the center on handlebars. Go to a department store and look in their accessory rack.(Target, Walmart , Sears) etc.) You will find strap on bottle cages. Bike stores are just going specialty.
Never Give Up!!!
As noted DON'T !!!
Get a universal mount, and put on the cage you want. Or make a mount - an aluminum tube sawed in half length wise, some rubber for the inside for friction and to protect the paint, then some sort of fastening scheme - zip ties, hose clamp, whatever you want. Paint it nicely and it will look great - or just polish it.
Thanks y'all for the replies. I'm convinced drilling the down tube is NOT the way to go.
Xerxes, thanks for the links. Nordicgroup.us was especially helpful (and entertaining).
I'm going to try a Minoura BH-60 bracket that clamps to the bars and centers a cage in front of the stem.