T. S. Eliot’s Prufrock laments that his life has been measured out in coffee spoons, but I think I could take a pretty good measure of my own life in bicycle tires. There was the orange Huffy of childhood that I transformed into something I called Tiger Bike, complete with a furry tail given out at the Esso station during its “Put a Tiger in Your Tank” promotion. Later, there was a 10-speed I took to college, where it was stolen from a friend’s house. In my 20s, I owned a Lotus racing bike. Once, I got my shoes so hopelessly entangled in its toe clips that I spilled right onto the asphalt of Connecticut Avenue in Washington, D.C.

Now, in my 50s, I have two bikes — a Specialized Secteur for the road, and a hard-core Trek Fuel 70 for the fire roads and logging trails of Kennebec County. Me.

When my sons were in elementary school, there were weeks in summer when they’d jump on their bikes in the morning and disappear down our dirt road with a crew of other boys from the neighborhood. “Bike patrol,” they called themselves. They’d head off to the lake, or to one another’s houses, or — who knows? — to secret locations that I, as one of their mothers, will never know.

I have several friends who partake in something called “spinning,” which is the health-club version of cycling, involving a group of women on stationary bikes who pedal fast, then slow, then fast, as the instructor blasts the kind of music you usually hear in stores that are trying to get 16-year-olds to buy pants, and yells things like, “Feel the burn!”

I prefer exercising at least two miles away from any other human being. For me, biking is a solitary activity. In the Kennebec Highlands, on my mountain bike, I pedal past Kidder Pond, up to the blueberry barrens high atop Vienna Mountain. From there, I watch bald eagles and ospreys, and other birds, whose poop, owing to their diet of berries, stains the gray rocks purple. Sometimes I’ve run into deer and porcupines, and on one memorable occasion, a moose. Another time, I lay with my back against a tree, watching a beaver build a dam in Boody Pond.