The sleek and collapsible Puma Biomega UM (short for Urban Mobility) renders the city bike easily transportable and travel-friendly. The lightweight aluminum frame reduces in size by 50 percent with the flip of a latch. What's more, the bike comes with a theft-resistant built-in lock and a pin-release system, so that you can loop its hidden wire around a lamppost or tree for extra protection. With just one simple speed, this might not be the bike you'll take to San Francisco, but its BMX-style handlebars give you all the balance and control of a high-end mountain bike— perfect for navigating city streets in style. $775; www.puma.com.