Rebuilding and repainting fixed gear bike?

Question

can i use bondo to fill a small dent on my top tube?

oh and should i primer the frame before painting it?

i have already sanded it down. but my friend says the thin layer of paint left on the frame will work as a primer. one more thing, how should i remove the brake k***s on the top tube?

Answer 1

Yep, Bondo works just fine to fill dents....I've done it myself a few times.  Be sure to roughen up the metal first.  As for painting it, depending on the paint that's on there and the paint you're going to use now....and upon how much paint you left behind, then you might be able to just put the new paint on top of that without primer.  If you want the best paint job, however, brush or strip all of that paint off, use a quality compatible primer that is intended to go with the paint you want to use, and follow all of the usual steps that you would if you were painting any metal or auto body.  You can do it fairly cheaply at the auto store, or you might find a great deal using a body shop if you bring the frame in prepped and ready to go.

I just answered your other question about the cable braze-ons....since now I know you're doing a whole refinishing job, I'd say to heat up those suckers if you're comfortable with a torch and steel.  

Good luck, have fun with the project, you'll be proud of it!   :o)

Answer 2

it IS a steel frame, right?

Answer 3

Bondo is fine, but leaving the old paint on is not. Keep in mind that a fresh coat of paint does not "fill in" scratches or anything and it really doesn't take much effort to completely remove the old stuff.

You can cut off the braze ons and file them away if you so desire, but I would just leave them on in case you want to switch back...

1) After completely disassembling the bike have it sandblasted to remove ALL the finish. If the frame is aluminum, it should be walnut shell blasted, or you can chemically strip the paint.

2) Spray it as soon as possible with grey SANDABLE lacquer primer. DUPLICOLOR brand paint is all lacquer, I think, and you can get it from your local autoparts store. Buy the BIG cans, not the small ones. Apply at least 1 full can, in coats, 15 minutes apart. Don't worry about light runs for now.

3) Wait at least 48 hours. There is a difference between dry paint and cured paint... it needs to be cured. Sand the primer using 220 grit aluminum oxide paper (white in color) until the surface is smooth. It shouldn't take much unless you have a lot of runs.

4) Using a tack rag, lightly go over the entire frame (don't rub!) to remove the sanding dust.

5) Apply several light coats (3 or 4 perhaps) of the color of your choice. Make sure the frame is completely covered. Follow the directions on the can. Again, use LACQUER, the same brand that you used for primer. Apply coats 1/2 hour apart. Be sure you cover every part and do NOT get runs. If you get runs you are applying it too heavily.

6) Do NOT sand the color coats. Apply the LACQUER clear coats, perhaps 2 full cans worth, coats 15 minutes apart..

7) Let the frame alone until you can't smell the paint anymore when you get up close and take a big whiff. If you can smell it, it ain't dry! This will take 2 to 3 days at least.

8) Wet sand the entire frame CAREFULLY with 800 grit, then 1000 grit sandpaper. Make sure to keep the paper wet and to wipe away the white slurry that forms. If you start to see the color in the slurry, STOP! You have sanded too hard and reached the color coats. Repeat steps 5, 6, and 7, then try again. Don't try to "touch up" the area, it will look terrible.

9) Using white paste polishing compound, follow the directions and polish out the whole frame.

10) Do NOT wax or wash for at least 10 days.

If you rush this you will end up with a sloppy mess and you'll kick yourself for ever trying. However, if you take your time and do it right it'll be a very cool feeling.