9. No need to go to the shower post-ride when you bike in to work. Just whip out some shampoo, lather-rinse-lather-rinse, and you're good to go. Make sure you wipe the road spray off your shins, though.
My pale muddy shins finally get to the office
8. Cars are usually a little slower on roads with standing water in them.
7. Bicycle tires do not hydroplane. Really. Sheldon Brown said so.
Yes, those are toadstools
6. Great chance to rinse the mildew off of that rain jacket that's been sitting in your bike bag all summer.
Great thing about Arkel panniers - they have the best rain cover ever!
5. Validates your choice of cycling footwear: Sandals. The water just kind of pours out of them. You would love to be able to show this to that racer guy in the Sidi Ergo 2 Vernices who laughed -- yes, laughed! -- at your Shimano SH-SD65s them last weekend. But you won't see him out biking in the rain today, since he just drove past you in his new red Ferrari. That bastard.
4. It rinses the dry dirt and grime out of your drivechain and brakes ... replacing it with nice new wet dirt and grime.
3. For those who ride the greenways and multi-use trails, there are fewer baby strollers to zip around and less strain on the vocal chords from yelling, "On your left!"
Where is everybody?
2. Validates your choice of keeping real fenders on your bike. Remember last weekend when the friend of the guy with the Sidi Ergo 2 Vernices -- the one on the new Pinarello Dogma with electronic Dura-Ace -- yeah -- when he laughed -- laughed! at your fenders? Well, you'd love to see him out here today, getting rooster tails shot up the back of his fancy Assos ss.13 jersey! Of course, he just drove past you in his new red Lamborghini. That bastard.
And the number one Great Thing about Biking in the Rain is ... you get to ride a bike!