Boston has one of the most successful bike sharing programs in the country. With over 100 solar powered stations and 1000 bikes available, the Hubway system makes it easy to ride around the city. 24hr and 3 day passes are available for only $5 and $12.00. Be aware that there is an additional charge if each singular ride last more that 30 minutes, so if you want to ride for the day, look into one of the shop locations. Even in winter, you'll see commuters getting to work on their bikes, taking advantage of the cities plowing and commitment to alternative transportation. PS-you do need a helmet.