From the point of view of a pedaler, New York's five boroughs are flat and conveniently concentrated, connected by spectacular bridges affording stunning views. That's why, every day, more than 100,000 New Yorkers defy the motorized competition and take to the streets by bike. The first step to joining the brigade is finding a shop-pick a place close to your home that offers free tune-ups and discounts on maintenance. Some push specifically designed "city bikes," but Martin Drake, a sales manager at Bicycle Habitat, recommends simply swapping a mountain bike's fat, "knobby" tires for skinny "slicks" that make pedaling easier. Mountain bikes are easier to maneuver, their gears are gentler up hills, and their frames are built to head off-road on the weekends. This year's model of choice, Drake says, is the Trek 6000, with a shock-absorbing front-wheel fork and durable, high-quality parts. It's mid-price, at about $530, but add another $90 for the special New York City-edition Kryptonite lock. Plus a (free) second chain to lock down the seat. Oh, and don't forget electrical tape, to make the shiny titanium frame less tempting.