I've been putting the old saying "It's just like riding a bike, you never forget" to the test this weekend, having avoided that particular activity for the last 20 years. I'm considering buying a bike and doing some riding as a more air-cooled form of summer exercise, so I rented one this weekend to regain some basic ability. So far the results have been mixed as to whether it's possible to forget how to ride a bike: it only took me 45 minutes riding in circles around a parking lot to regain some ability to balance, turn, and stop, but the ground sure does seem further away than when I was twelve. Goal for tomorrow morning: relax my death grip on the handlebars and hopefully end up not feeling like I've been bench-pressing weights all day, as I do right now.
Update: moderate success. I certainly feel less trashed this evening than I did yesterday, after riding for somewhat longer today. I even saw one person on the trail that I was probably more skilled than. Of course, he was about 7 and using training wheels.