Kinda off-topic, but here is my case for drinking and riding:

I worked for a guy in SF who encouraged me to chill out and have a beer after an altercation with a driver. He felt it calmed the nerves a bit and prevented you from riding all angry/scared.

I don't think alcohol really slows people down that much. Back in the day they used to give six day racers alcohol and speed to keep them going.

I raced bicycles for a few years and never won anything. I did well enough in road and cross races to upgrade to cat 3, but never did better than 2nd. I am pretty timid on the bike, I would get gapped on technical descents and have to chase back on. When I was a messenger it was the same story. I was pretty fast at work, drank moderately during the races, and knew the city. I did well in alleycats but never won. Last year I got wasted the night before a race, stayed out half the night, crashed, woke up buzzed and just ran with it in the morning. Sparks for breakfast and a beer at every checkpoint that offered. I took more risks, stayed relaxed, hit on checkpoint workers, and won. I think I corner, descend, and maybe even climb faster when drinking.