London's former mayor, Boris Johnson, is a real cycling enthusiast and was keen to make the capital more bike-friendly. A 24-hour bike-rental program called Santander Cycles enables Londoners to pick up a "Boris bike" at one of more than 700 docking stations and return it at another. The first 30 minutes are free, then it's £2 for every 30-minute period thereafter. There is also a £2-per-day access charge. Fees are payable online, by phone, or at docking stations, by credit or debit cards only—cash is not accepted. To sign up, a user goes to the TfL (Transport for London) website and then receives a bike key in the mail, so this very popular system is really only practical for locals, not most tourists.