Slackliners

They may look unbalanced, but their wobbly sport is catching on

Most people can walk in a straight line. The State Police think you should be able to put one foot in front of the other until your blood-alcohol content hits .08. Which is probably why the slacklines - five of them, jumping from tree to tree in the shape of a rough pentagon - looked so inviting to the passersby on the Esplanade on a recent day.

Over and over, they approached with a simple idea in their head: I can walk in a straight line, so it stands to reason I should be able to walk on a straight line. And over and over, they fell, ugly, laughing. Some could not even get on the thing.

Slacklining is a relatively young sport in which you walk on a "slack" band of flat nylon webbing anchored between two points, usually with slings around trees. Pioneered by West Coast rock climbers in the early '80s, slacklining has been booming in popularity in recent years, particularly on college campuses, and is catching on in Boston. This city's first organized club formed this summer, and its members set up their lines near the Hatch Shell on Sunday afternoons.

Slacklining is, however, quite different from walking on a tightrope. The line is taut enough to support the walker - this is achieved by tightening the line with a ratchet or carabiners - but still slack. The tension on a slackline comes from the weight of the walker, which makes each step different from the last. To a newcomer, the line feels like a rubber band intent on throwing you to the ground. Many will get just one foot on the line, feel it vibrate to life beneath their feet, and say, "Thank you very much, but I have to work in the morning."

For those who continue farther -such as Tom Roloff, who stopped on the Esplanade because his kids, Jackson and Alexandra, age 6 and 7, wanted to try - the first moment where you are left alone to fend for your balance will make your knees wobble like you've just been fooled by a curveball.

"This is way harder than it looks," Roloff yelled as he fell off, arms flailing as if he had been pushed into a pool. The lines, for this reason, are usually just a couple of feet off the ground; but being that this is a sport that descended from rock climbing, there is an entire subgenre - highlining - that involves walking across extreme heights.

"Daddy, it's easier to be in bare feet, and bend your knees," Jackson, who was much better than his dad, said correctly. It's also advised to pick a spot on the tree in front of you and focus on it, and to use your arms as your balancing pole.

To overcome feeling "like a teetering pile of dishes," as The New York Times described it, you've got to get very zen and relax. You cannot see balance, only feel it, the mantra goes. You can't overthink it, and those who have been bitten by the slackline bug say that is its key attraction.

"It's a meditative experience," said Doug Neill, 23, a PhD candidate in physics at Northeastern who picked up the sport as a college student in Oregon and created the Boston club through the social networking site, meetup.com. "You need to put all your energy and focus into staying on the line. It requires so much concentration to stay up there that it forces you to completely forget about everything else. It can be very cleansing."

Everything you need to slackline can fit easily into the bottom of a backpack, and you can pick up a rig from several online retailers. Slacklineexpress.com sells a 30-foot beginners' ratchet kit for $45; if you know anything about using carabiners, you can make your own, although a ratchet kit is easier to set up and tighten, especially if you're alone.

Despite all the giggles and legs-bouncing-like-a-kid-on-Red-Bull feeling of that first foot on the line, the learning curve is not as steep as many newcomers expect. After one good session, you might be able to balance on one foot. A couple more, and you may be able to get both feet on and take a few steps. Some have a natural knack - or they're artificially relaxed.

"The best newbies I've seen have been trashed," said Sven Cattell, a 20-year-old BU student who has taken to setting up his slackline on Commonwealth Avenue after midnight. (At any other time, he says, he can't get a good practice in because too many people ask to try, and he obliges.) "Except for the BU ballerinas. They could walk on it within 15 minutes, which is ridiculous. None of them moved their arms. They all balanced in their hips."

Cattell caught the bug about a year ago and has progressed past the walking and turning phase to the inevitable: tricks. He can sit down on the line cross-legged, lie down, jump, do a 180, and execute what's known as a "helicopter," in which one turns with each step. On YouTube, you can find people on slacklines juggling, unicycling, doing yoga poses, doing flips, and pretty much everything else you can think of.

"There are no rules, no set of instructions," Neill said. "It's a new thing, and it can be your own thing. You can create. It's one thing to see somebody do a trick, but it's another to make it up all on your own."