Riding a bike, like shovelling coal into a locomotive's engine or bench-pressing a saddled horse, combines physical exercise with advancements in human transportation. Make the best of self-propulsion with today's Groupon: for $47, you get a one-year bike-rental membership to Bixi (a $95 value).

Bixi's fleet of bikes awaits riders 24/7 in 80 self-service stations located across the city and provides an ecological alternative to carpools. Three to five business days after acquiring their online subscription, customers receive a Bixi key that activates their personal accounts and unveils the bike paths leading to Narnia. A one-year membership includes an unlimited number of rides, each of which can last up to 30 minutes without paying for additional time. The bikes are available 24 hours a day. Members swipe their keys on the post to which their elected bike is attached, enjoy a self-fuelled ride, and return two-wheelers at the closest station to their chosen wormhole.

For commutes longer than 30 minutes, additional fees are added according to the duration of the ride ($1.50 for 31–60 minutes; $4 for 61–90 minutes; and $8 for each additional half hour on rides longer than 90 minutes). Smart phones can access an interactive map of Bixi's bike network, which keeps track of the closest stations and whether bikes are physically available and mentally prepared at any given time. Customers can refer to Bixi's FAQ page to enhance their experiences.