rust a danger under electrical tape on steel frame?
 

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:
http://www.unc.edu/~cupery/pics/bike...d_downtube.jpg
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.

Surface rust isn't a big danger. However, I don't think electrical tape will be an effective way to prevent its spread! Electrical tape is fairly porous to oxygen and other gases (I work in a lab where we have to handle all kinds of gases and I can tell you that electrical tape is completely unsuitable as a sealant).

The best solution would be to lightly sand off the rust, then touch up the paint with black nail polish or automotive touch up paint. I did that on my old fixie and it looked great... you can judge for yourself from the photo (see the link to my bikes in my sig).

Cool, thanks - that's the info I was looking for (about electrical tape being porous). Good to know.

The other question is, would electrical tape (for the time being) create an incubation environment where rust would spread more than it would if just exposed to the outside air? (assuming bike not left out in the rain)

being in aviation, Ive seen what covered rust/corrosion can do...out of sight, out of mind....before you know it, your frame is trash. the only way to stop it is to remove the rust(30 min with some sand paper),and if it's a quick fix youre looking for, get some krylon or rustoleum, and then clear coat it. Or listen to Mox, he's 100% correct as well. I use touchup auto paint for my touring bike for small spots.

when ill-advised electrical tape application is actually a good thing
So I had actually wrapped the rusted part of the down-tube in electrical tape before my initial post in this thread. Should have waited, but I figured that I could take it off easily.
Well, when I unwound the tape from the downtube, it took lots of the paint with it. The paint just peeled away, stuck to the tape and not to the frame. Just for comparison I wrapped a small section of the upper seat tube in electrical tape, and peeled it off, and paint did not come off with the tape. Basically, the rust had spread enough under the paint on the downtube to weaken the paint's adhesion to the metal, and so in a sense it's good that I made the mistake of applying and then removing the electrical tape to the downtube, because then I realized that the downtube needed to have rust carefully removed and then repainted with something.

Sounds good to me! Electrical tape might not be good for PREVENTING rust, but apparently it's good for DETECTING rust :)

It looks like you've a good candidate for the rattle can.

I'd get a steel brush on my drill and flake off some of that paint then give it a light sanding.

Here's my rattle-canned Le Tour with electrical tape on the bars.

http://i77.photobucket.com/albums/j7...dt/letoura.jpg

Nice - another old Carolina-blue Le Tour. (Mine came with the original paint job that same color.) It looks as if you put a new(er) seatpost on there. Out of curiosity, what size fit in there without the shim? And what year is the frame from?

Tim,

I still have the shim on that SR Laprade 25.8 post. I can't recall what old bike the post is from.

The Le Tour is an 82 - one year before cro-mo.

I''ve got an 8-speed cassette and 700 wheelset on it now.

Yeah... I love that Carolina blue color (born in Chapel Hill myself :D). I've lusted after the Super Le Tour for a couple years, but never found quite the right opportunity to buy one.

Yowza. Chromed fork. Groovy, man ;-)