I do a lot of parts cleaning when a bicycle comes in to be reconditioned with a new paint job and overhaul. Lets pretend that this might be something made before 1983. Because I paint a lot of frames, I tend to use products involved with that process. I think other list members would find an automotive paint supply store (that would sell DuPont Imron paint for example) a real resource for cleaning supplies. A pair of gloves made of Nitrile material is much better protection than gloves commonly found in hardware or grocery stores. They are designed for protecting your hands when cleaning paint spray guns. I use lacquer thinner as a powerful solvent for stubborn grease or whatever. I'm sure it isn't people or environment friendly but works great. Another useful tool is a brush that looks like a tooth brush that withstands these stronger solvents and won't melt when in contact with them. An additional product that is sold in this store is a paint cleaner used to prepare a painted surface before reapplying more paint. It is a much milder solution and won't soften the paint when used like lacquer thinner will. It is designed to be just strong enough to get rid of surface crud without hurting the paint. It also works as a parts cleaner but, again, isn't as strong but is also more user friendly. The expensive stuff has an anti-static additive that has no application to general cleaning.
I find an ultrasonic cleaner marginally helpful. I commonly use it on chains where it is most useful and appreciated and rear derailleurs but could live without it. To get really clean, hand brushing always seems necessary.
Doug Fattic
Niles, Michigan