With bike share programs popping up all over the world, it's easier than ever to skip the rental car and see a new city on two wheels -- or cut your carbon footprint by riding around town instead of driving. And as each city puts its program together, the focus is on one very important aesthetic: The bikes themselves.

From the all-American red of Capital Bike Share to the sophisticated muted tones of Italy's BikeMi, here's some of our favorite bike share bikes around the world.

The patriotic red of Washington, D.C's Capital Bikeshare bikes is just part of what turned this 2008 upstart into the biggest bike-sharing program in the country: Though it already boasts more than 1,000 cycles at 114 stations around town, the group announced plans to add nearly 300 more bikes in the fall of 2011.

Paris launched its bike share program, Velib, in July 2007 with more than 10,000 bicycles placed around the City of Lights; by its fourth birthday in 2011, the program was offering more than 17,000 bikes at 1,202 rental stations.

But who wouldn't want to pick up one of the sleek gray bikes -- complete with a front basket -- to avoid the traffic while picking up a baguette from your favorite boulangerie?

Istanbul isn't a city that's known for its friendliness to bicyclists -- one rider quoted in a piece on EurasiaNet said, "Other drivers on the motorway act as if they don't see you. You are a ghost." -- but if you're willing to brave the steep terrain and the vehicles, you can grab one of these royal blue bikes from Ispark.

Melbourne also chose a vibrant blue for its shared bike program, which launched in 2010 but didn't get rolling quite as quickly as organizers had hoped.

A year after the program's beginning, Australia's The Age reported that riders were still making about 2,000 fewer trips each month than needed to subsidize the cost of the program, but that plans for additional bike parking locations could improve the ridership.

Hubway, the bike share program for Boston, Massachusetts, debuted in the city in July, 2011, with more than 600 cycles installed at 61 stations from Seaport Boulevard to Harvard Stadium.

The city has also installed or has plans for a total of 12 more miles of bike paths to make it easier for residents to get from Point A to Point B on these metallic gray cycles with Green Monster-inspired detailing.

There's no missing these bright green, red, and yellow bikes from the Taipei bike sharing program Youbike which began in March 2009 with a pilot program of 500 cycles that were used by 20,000 customers in the first six weeks.

Following the success of the Parisian Velib program, Montreal also jumped into the world of bike sharing.

They started what the New York Times called "the continent's most ambitious" program, Bixi, in May 2009, with 3,000 cycles.

Not sure you want to brave a rental car -- complete with driving on the wrong side of the road -- in London?

Stop by the Barclay's Cycle Hire instead, where you can rent an appropriately sedate navy blue bike (and still feel like you're traveling like a local thanks to the Underground-inspired logo on the side).

Nice Ride, the Minneapolis, Minnesota bike sharing program, has been offering up these flashy flourescent bikes since 2010 -- with more than 100,000 riders hitting the streets in the first season alone.

But don't expect to get a bike if you're visiting in the winter: The snowy season means the bikes are only out from April to November.

BikeMi, the bike sharing service that provides residents and guests of Milan, Italy, with their own two wheels, plans to fill the city with about 5,000 cycles -- making it easy to go from art museums and coffee shops to the Duomo and the flea markets sans car.