To protect the right hand chain stay from scratches from the chain when you remove the back wheel, make a protector out of soft vinyl/PVC plastic tubing - this sort of stuff:
http://www.hudsonextrusions.com/indu...rade_vinyl.htm
1. Measure the rough diameter of your chain stay, being a bit generous. Buy hose from the hardware store with an internal diameter close to or slightly larger than the chain stay diameter.
2. Cut to length so that the protector stretches from the intersection of the chain and seat stay, up until under the cage of the front dérailleur. Gardening secateurs are good to cut the hose with.
3. The hose will have a natural slight bend, and if your chain stay also has a bend in it, you can match them up.
4. To spit the hose, clamp the hose between a block of wood and a metal straight edge of some sort e.g. something like a metal strip. When you clamp the hose it'll compress, causing the place where you're going to cut it to buldge out, possibly more than you want. Adjust it until the only part of the hose buldging out from the straight edge is the part you want to cut off.
5. Run a utility knife (box cutter, or commonly known down here in Australia as a "Stanley Knife") along the straight edge. The hose is fairly soft, however it will take a number of runs to cut completely through it. As you're likely to be pulling the knife towards yourself to get the right amount of force, be
very careful not to pull too hard that if the knife let go you'd stab yourself. This is why a number of runs along the straight edge is better and safer.
6. The edges of the hose where it has been split will be a bit sharp, possibly sharp enough to scratch the frame. Using a blade edge like on scissors (i.e. sharp but not too sharp), scrape the blade along the edges of the cuts at a fairly steep angle to dull them - also being a bit careful about using a blade (at the right angle, or if you accidently close the scissors, you'll cut yourself)
7. Tada. Now when you take the back wheel out, there is no chance of the chain scratching the chain stay.