how to fill holes in the frame before paint?
 

I have an old cannondale road bike that I converted to a fixed gear. I took off the cable guides, shifters, etc and it looks great. There are holes in the frame that don't look so hot though.

What can I fill them with? It would look better if I can fill them with something and touch it up with the same color paint. anyone got an idea?

you could probably use bondo filler, just like on a car.

i used bondo. worked fine. the hole was the size of a bb. you may have to get something welded if the holes are large.

I also used bondo to fill a small dent in my top tube. No problems so far.

are these drainage holes? they might be a bit important.
or are they speed holes?

jeff

If you use bondo, you might want to prime the bare metal surface to give the bondo something to stick to so it doesn't fall out over time (this may not be necessary, I'm not sure).

I'll be quickly corrected if I'm wrong, but I think that many of these holes are to allow gas escape when the frame is welded.

Check the packaging of your filler, some require a primer, others do not, just do what it says on the package. Bondo sells a version in a tube, which would be handy for filling small holes, just squeeze on a tiny bit, smooth it with a curved piece of plastic (like a bent credit card, that you aren't going to be using again ;) ) When its dry, sand it smooth with the metal, and paint away.

peace,
sam

Are these weep holes? Are rust pits or holes that rusted thru? If it is that far gone you will want to check with you LBS to see if the frame is safe.
Bondo works great. You want to sand the area to remove all the rust and loose paint and rough it up to give the bondo something to adhere to. After sanding use acetone to remove dirt and oils. Make sure you follow any specific mfr's instructions and be patient. Work slowly, don't try to sand off to much at once. The problem is once you do this repair the area you need to repaint will be larger that the little hole you started with. You need to decide how much work you want to put into it and what level of finish you want.
Good luck.

My 2 Centavos.
OK, Bondo is $10 a can, while two-part, five minute epoxy is $2.00-3.00 a tube. The epoxy is tough and is not as prone to moisture penetration as bondo. Having had cars which reached the 1 to 1 bondo to sheet metal ratio, I can assure you bondo will vibrate off of even the most well prepared steel over time. It may be years, but it is not a lifetime solution when applied much thicker than a sheet of paper.


0. Sand, file, or scrape the inside of the holes you wish filled with some abbrasive.
1. Push some kind of plastic scrap or stryro foam into the hole. Push it about half-way down into the hole.
2. Tape off the surrounding area.
3. Mix your epoxy.
4. Lay in your epoxy.
5. Let the epoxy dry.
6. Sand, file or buff.
7. Lay in some more epoxy to fill any irregulatities and sand, file or buff again.
8. Prime.
9. Paint.
10. Enjoy.

Post a photo if you can.

it took me a second to realize that you meant bb, not BB.

Holy Cr*p. Being Canuk, I have driven many a car with holes in it. A bike frame with holes scares me.

Are you talking about the holes on the downtube where you removed the shift bosses ? Aslo the hole from the screw that held the rear derailer hanger on ?

Tony

Fixed gear? They're not holes, they're piercings. Install studs.