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Most cyclists I know enjoy their adult beverages as much, if not more than their caffeinated ones (and they LOVE coffee), in fact, it's been said that the perfect group ride starts at a coffee shop and ends at a brew pub (cyclists love their microbrews, and apparently, microbrews love us back). Additionally, it seems like component and tool designers are compelled to put bottle openers on every possible piece of equipment, from multitools to baskets, and even incorporate them into the bicycle frame on occasion. Bikes and booze are pretty good buddies.
It seems like the health benefits of bike riding, along with the health benefits of (moderate) alcohol consumption go hand in hand, and the social aspect of wrapping up a strenuous ride by enjoying a couple of tasty beverages together is a great bonding experience. A post-ride pub stop can turn a dreary, foul-weather ride into an epic adventure, and a pleasant ride into a fantastic outing.
Furthermore, in areas where there are several brewpubs or vineyards to be found, a bicycle can be the ideal way to tour them. Riding along gives you a chance to enjoy the scenery whilst burning off the calories (and alcohol) between one stop and the next.
The key, of course, is moderation. In many areas it's illegal to operate ANY vehicle while intoxicated, including a bicycle. If you're really drunk, your perception and balance will be impaired, which means taking to the streets to dodge traffic is not a good idea at all. A lot of fatal bicycle accidents in urban areas are due to drunk riding. There are those who feel that if they're just a bit buzzed, riding a bicycle is far safer than driving, which considering the slower speeds and better maneuverability of a bike compared to a car is probably true, but as a more-or-less responsible blogger who puts my real name on things, I can't ethically encourage riding impaired at all (if you do have to stumble home, walking your bike and leaning on it for balance is fair game).
If you happen to drive to the pub and have a few too many Saturday night, your best bet is of course to get a ride home from a friend or a cab. In this case, a Sunday morning bicycle ride may be your best friend (along with Gatorade and Advil). I've... heard that in the case of a mild hangover, working up a sweat in the morning can help clear it up much more quickly, and a leisurely ride to go pick up your car from wherever you left it might be just what the doctor ordered.
Bikes, beer and wine have a long-standing, mutually beneficial partnership, so go on and have a pint after your ride, just be moderate and responsible.