WHEN JOHN KERRY took a spill from his bike this past weekend, it triggered thoughts of Jimmy Carter’s collapse in a road race, Gerald Ford’s much-mocked stumbles, and of Kerry’s own misadventures on the ski slopes earlier this year. But it wasn’t until the pictures of Kerry on his bike appeared that the real damage was done. The electric-lemon Lycra look probably won’t play well outside the metrosexual caucus, and it can’t be particularly inspiring to the troops living in holes outside of Falluja. Presidents can golf, and they can run, but they can’t get dandied up and dart around on bikes in tights and fluorescent helmets.

Kerry’s obsessive, if ill-fated, displays of physical activity also raise issues other than decorum. I’ve seen this sort of behavior before in men of a certain age, usually from their early 50s to their early 60s. And then the thought stuck: Are John Kerry’s presidential ambitions and the shape and images of his campaign more about a mid-life crisis writ very large than any underlying set of ideas?