Use shampoo (the stuff you use on your hair) in warm water rather than washing up liquid, then rinse off with clean water to get rid of most of the dirt. Do not use a pressure washer; use a hose pipe or pump-action spray like gardeners use. Dry everything down with a cloth. Run the chain through a cloth to remove most of the gunk, then either remove it (if it's fitted with a QR link) and clean it in a tub of white spirit, or leave it in place and use a chain cleaner loaded with white spirit. Wipe dry thoroughly. Use white spirit and a small (half inch) paintbrush to clean the cassette/freewheel, front mech/chainset, rear derailler, brakes and any other working parts you can think of; the combination of the solvent and agitation will simply wash away all the dirt and contaminants and free everything up. Rinse the working parts with clean water to ensure any remnants of white spirit are removed, dry again if necessary and/or spray liberally with your choice of 3-in-1, WD40 or GD85, wiping off any excess. Clean the wheels and spokes with a cloth; once again, white spirit and/or penetrating oil are your friends if you need them. Lube the chain, jockey wheels on the rear derailler, and front mech with the best quality lube you can afford. Time: 30 minutes.