A bicycle, or bike, is a human-powered, pedal-driven, 2-wheeled vehicle. Bicycles are used for cycling.
 Bicycles with lever arms
Bicycles can be equipped with lever arms, in order to reduce the effort required for the bicycling. The first bicycle with a lever arm was built by Maurice Houbracken. The effort required "reportedly" reduced the effort required by 50%. After a conversation with the builder though, it is clear that the system was built immediately without much prior designing. This would mean that much improvement is still prossible (ie the lightgreen lever arm could possibly be attached elsewhere, on a more favorable position, and the angle might also be changed). Also, by increasing the lever arm, the fabricator stated that a 100% effort reduction is definitely possible, and perhaps that a redesign is thus useful for other purposes (ie vehicles where the driver takes another position; ie such as with the AT e-velomobile). Also, a similar lever arm could also be used for purposes other than transportation (ie winching, ...).
 Electric bicycles
Bicycles can also be fitted with an electric motor and a battery. If recharged with renewable energy, this is another sustainable option. Less effort means less sweat, but also less of the benefits of exercise. A great option when covering long distances or avoiding sweating (e.g. on the way to work in hot weather).
 Bamboo bicycles
Speculation follows: The likely difficulties include:
- Getting consistent size and shape of bamboo.
- Consistent mechanical problems (only if mechanical parts are made of bamboo or wood as well).
- Avoiding splitting by use of special fittings and glue (mentioned in the article) - yet it must still be strong enough to safely carry a rider.
- Does the bamboo potentially create large splinters in the event of a serious accident? If so, these splinters could cause serious injuries