Originally Posted by
Dan Burkhart
Is this an electroforged Chicago Schwinn? If so, the frame tubes might be thick enough to drill and tap to m5x.8. I did this on my Schwinn Twinn tandem, even though I am equipped and able to install rivnuts. The tubing was thick enough for 3 full threads, enough to secure a bottle cage.
If I were snooty, I might point out that a seat tube with a wall thick enough to tap 3 full threads might best the best argument against bothering. (but I'm not)