Guess what? It's National Bike Week! If you read street style blogs, you've seen thousands of model-pretty girls riding bikes in high heels and flowy dresses with perfect hair cascading behind them. This is because people in the street style world don't sweat, get their heels stuck in their bike pedals, or worry about the prospect of catastrophic brain injuries. In the real world, it's a little tougher to look stylish and cool on a bike, but it can definitely be done, and the payoff -- getting fit, breathing fresh air, saving the earth -- is so worth it. Whether you're biking to work or taking a lazy Sunday ride, here are five essential pieces that can transform almost any outfit into a bike-friendly one...