Adrenaline can fix a lot. And by "fix" I mean shift your psychological hyperspeed gears and make them run at a normal rate, rebalance your skewed perspective, and melt everything just a little bit, bringing life back to the solid ground. Adrenaline has no room for invitations or formal wear or calendars or email. Hydration and sunburns are allowed.
Cycling is different from running or other city-friendly sports because you need to think about survival. And when you're thinking about survival -- not getting slammed into, not getting doored, not riding over that perilously wide-slatted sewer grate -- your brain clamps down into alive mode. People who don't know what this is like -- and this is some pretty mild survival mode stuff, talk about vertical wall climbing and mountaineering -- are missing a very important part of the human experience, something so important that I would go so far as to say they are literally disabling themselves. People who have not had their very existence challenged in some way -- even if it's something as small as having to swim away from a very big wave at Jones Beach -- are really missing out. (RE: people in spin class.) They get stuck in psychotic loops of modern thinking: your daily world becomes smaller and smaller, the not-so-important details of your little urban life become quite important, you start sinking into an oppressive quagmire of anxiety and getting enough sleep. I am course talking about myself, and then I went on a bike ride.
No party is ever worth losing the ability to do this.