I just built an old Schwinn Le Tour Luxe into a relatively nice 12-speed road bike for a friend (rachet levers on 12-speed drivetrain, aero brake levers, all nice alloy components as opposed to what came stock on the bike, weighs around 25 pounds).
There's a lot of paint chipped and some rust spots on the downtube. Not deeply-rusted spots, it's still very much on the surface of the tubing so no structural danger, especially given that the frame is a 25" frame which Schwinn didn't use butted tubes because they didn't want the large frame to be too flexy. Here's the worst of the rust:
I'd like to wrap the chipped/rusted part of the downtube with electrical tape as a quick and easy solution against future corrosion. Here's my thinking: rust requires oxygen to continue forming, and electrical tape (when wrapped tightly in multiple layers) forms an effective bond against oxygen's entry. The black color doesn't even stand out that much against the dark navy blue paint on the frame.
My only worry is that the electrical tape may form an effective incubation area for rust. However, the frame is being kept indoors in air-conditioned area that's not humid, so the frame's exterior will be dry when wrapped with tape.
Does anyone have thoughts on whether this is safe or dangerous? A good or bad solution? Thanks.