A clean bike will look better and last longer, too. Depending on where and how often you ride, your bike may be exposed to weather extremes, mud, chemical residues and road salt. Your first thought may be to let a pressure washer do the lion's share of the surface cleanup, but that's a bad idea. Pressure washers and even your garden hose at full capacity can force water into your bike's bearings, which is something you want to avoid. Grab a bucket of warm, soapy water, a cloth and a brush and give your bike some up close and personal attention. Have a plan, too, like working in sections from the back of the bike to the front. That way you won't miss anything.
You might also consider making drivetrain maintenance on your bicycle a little easier by investing in a chain cleaning system that works with the chain in place. You'll save time and might end up performing bike maintenance more frequently that way.