With petrol prices continuing to rise, there’s no better time than now to hop on a bicycle to go where you need, provided it isn’t 30-50 miles away. Whether it be a TRON-inspired bicycle (above) or one made from cardboard, geeks have already begun thinking outside the box. Continue reading to see more.

5. Flywheel Bicycle

Mechanical Engineering student Maxwell von Stein might have come up with a reasonably simple alternative. His Flywheel Bicycle features a – you guessed it – built-in flywheel that harnesses the bike’s energy that’s usually lost when braking. When coming to a stop the kinetic energy is instead transferred to the 15 pound flywheel as it spins up. Then, at some point while riding, the energy in the flywheel can be transferred back to the bike’s rear wheel giving the rider an extra kick or boost.

4. Audi E-Bike

If superheroes biked to work, this is the bike Batman would hop on to beat crosstown traffic. Constructed of carbon fiber-reinforced polymer, the bike has a 2.3 kilowatt electric motor, a range of 44 miles, a lithium-ion battery, can reach speeds of 50 miles per hour, and weighs only 24 pounds. The bike also allows you to change riding modes via smartphone.

3. Boxx Bike / Scooter

On a standard configuration you will get 40 miles per charge. An upgrade doubles that. And the standard configuration charges the battery back up in 4 hours, the upgrade cuts that down to 1. The 1 meter sq. (36 inches sq.) device weighs 120 lbs and can carry a rider tipping the scales from 90-300 lbs. It goes up to 28mph to 35mph, a speed which is electronically limited depending on regional moped laws. The all aluminum construction features a glove box, a cargo bay, an all LED dot lighting system with hazzards.

2. Sofa Bike

Two sets of pedals connect to two separate 8-gear hubs allowing each person to carry their own weight, and hydraulic braking and steering are handled by a single crank located on the left arm of the sofa. It’s even got a folding roof that easily pops-up thanks to a set of assistive gas springs, and its own sound system powered by a rechargeable battery.

1. $9 Cardboard Bike

There are a number of interesting bike designs made from a variety of materials, but one factor always held true: they’re not generally made of cardboard. Well, designer Giora Kariv wasn’t having that, so he went ahead and built a bike out of cardboard for $9. Kariv brought his idea to a number of different engineers, all of whom told him that it was impossible. He did it anyway and managed to make a working bicycle that can hold a person of up to about 308 pounds.

[Sources 1 | 2 | 3 | 4]