Needed; 400 grit sandpaper, blue masking tape, a plastic grocery bag, can of dark gray primer, can of semi-gloss black paint (colors are just what I used for reference)
Step 1- Read directions on sandpaper, paint and primer. These companies have done lots of testing to see how their product works the best. Take their advice, you already paid for it (when you bought their product). Pay particular attention to spray distance, recoat times and total dry times.
I used a brand new set of rims for my painting process, so I got to skip a few steps. Otherwise; Take everything off the rims except the tires and the air valves. Tape the threads for the rear freewheelwheel/bearing/sprocket to keep them clean. Fill the 6 holes that the discs mount on to with little pieces of paper rolled up. Ball up paper towels and stick them in the bearing holes (middle of rim).
Also, let (at least) some if not all of the air out of the tire. Being able to work in the seam where the seal usually is seated allows you to paint more of the visible areas on the inside edge of the rim. You can always reseat the tire to the rim again after it's painted.
Cut off the rubber injection hairs on the tire that are directly around the inside of the edge of the tire. I cut one row under the edge of the rim, and the other row was about 1" up. To take them off, I stretched them with the tweezers, and then cut them off flush with the surface of the tire. The more flush you can cut them, the better will allow the masking tape lay flat against the tire.
Sand the rim with 400 grit sandpaper. Your not taking all the paint off, just texturing it a little to give the new paint a better surface to adhere to. It will also smooth out the bumps sure to be there in the OEM paint. Sand all surfaces till smooth (again, this does not mean paint free), especially the edges since their the most exposed to possible damage. Clean off all the sanding dust with a couple of passes with a wet lint free rag. Also clean the tire off for better adhesion for the masking tape.
Tape the sidewall from the treads in to the inside seam where it meets the rim. In the first pass, overlap the edge of the rim and the previous piece of tape laid down, but do not press tape down into seam yet or when it's cut it will curl up and block some of the surface that needs to be painted. The extra tape overlapping the rim will be cut off and pressed in later. Just over lap row after row until you work your way around the entire sidewall of the tire.
Then on the tread portion of the tire, wrap around the tread covering the ends of the tape you did on the sidewall. Entire sidewall and corner where it wraps around to the tread should be covered. Press all the tape pieces together and make sure their stuck down to the tire as much as possible.
Now press down the tape onto the lip of the rim until the outline of the outside edge of the rim is pressed (embossed) into the tape.
*** That takes us through
photo A (pressed in line changed to red line for visibility).
Now cut the tape along the line, and press the tape all the way down into the seam between the tire and the rim. Cover as much of the rubber down in the seam as possible. If necessary, cut small strips to cover portions of the tire that are exposed.
Wrap your plastic bag around the other side of the tire and cover the remainder of the tire that is not masked with tape. Bring bag up to the last row of tape you wrapped around the tread (4 steps back). Tape the bag down to the tape, and cut off the excess bag. Lastly, mask up the valve stem so it's not painted.
That takes us through
photo B.
Dust rim off one final time and hit it with a light coat of primer. Start with spraying from the outside, in towards the rims edge, down into the crack between the rim and tire. Then around the outside and work your way down into the rim. Sometimes it's easiest if you actually spin the wheel, while you spray the paint in at an angle to get the vertical surfaces. Spray all the way around the sides of the "dish", and then the bottom. Lastly, hit the post coming out that holds the axle. Make sure to spray up to the back of the flange that the disc mounts to. The wheel does not need to be covered in primer! Just a dusting (LIGHT COAT).
Following the same procedures, recover with 1 more light coat of primer, and then 2-3 coats of actual paint. The fewer coats you apply the smoother the finish will be in the end. On most painting projects, I would follow up with a wet sand at this stage. This started fairly smooth (from the beginning 400 sanding), and sanding a finished painted surface in such a tight area is too easy to sand through back to the primer, which would need to be resprayed.
If your paint is real bumpy, you can lightly sand it smooth with the 400 grit, and lay one good paint coat on it. Still easier than a color sand and polish finish in an area your hand cant fit in!
Let paint cure for recommended time, then peel tape off and admire your work! Move on to the other side, and then on to the next wheel. A few hours later, you have nicely painted wheels, without taking the tires off the rim (try that with powdercoating!).
That takes us to
photo C (with a plastic cap over the freewheel treads installed).
If you have to re-seat/fill up the tires, do it now. It is a LOT easier to add air to the tire before you bolt on the drive sprocket and bolt it on the bike! You can also polish the parts/hardware up before you bolt them back on. With two passes of chrome cleaner, I got the OEM drive sprocket to high polished finish that really pops against the black wheels! Again... A lot easier than after their installed.
Assemble wheels with brakes, rotors, bearings and the freewheel drive gear. Sand the paint (new and old) from inside of the wheel, where the bearings are installed. The easier it is to get the bearings in, the less chance there's going to be damaged by forcing them in. Don't sand it so far the bearing falls right in and out, just clean them up a little. Also, use a little LocTite on the screws that hold the rotors on.
Put wheels back on, adjust the brakes, and roll with your "new" wheels!
There are shortcuts that could be taken, but be forewarned! Bumpy finishes and overspray can make your paint job look very amateur. Take a little extra time in preventing it, and your paint job will show it in the end...
Color/finish choices; The colors and gloss choices will affect how many imperfections you see in the final piece. Lighter colors tend to reflect more light, which hides the imperfections in the finish. Darker colors reflect less light, which gives a higher contrast between the light and dark areas (of reflection). Summed up, dark colors tend to show off the dents, bumps and paint issues more that light colors.
On the same note, higher gloss finishes show off more than a flat or satin (semi gloss). So gloss black is traditionally the worst color for a spray can finish. On the other side, if you have a badly damaged piece in need of a clean up, Flat white will hide a lot of "stuff" unless you look real close.
Flat colors don't show off the curves of an object as well as gloss finishes. Since you don't see the reflections of the different angled surfaces, flat paint tends to make things.... Well, flat. So if you want to go lower gloss, try Semi or Satin (unless your going for the stealth look).
