While bicycles do take some resources to build and maintain (particularly various metals for frames and rubber for tyres), these are far lower than modern automobiles. Human-powered bicycles also do not require using non-renewable petroleum as a power source, do not emit any air pollution during use, and require far less parking space and heavy road infrastructure per person than is required for automobiles. They are also far less likely to kill and/or seriously injure cyclists or other street users such as pedestrians than heavy, motorised transport.
Consequently, there is much interest and renewed focus in the bicycle as an important part of the goal of Sustainable transport. This includes both in rural developing contexts, in urban centers in countries such as China and India where in many places the bicycle is still a majority form of mass transport, and in Western countries where explicit policies and infrastructure to encourage more cycling is seen as an important way to reduce the environmental impact of transport, and also to support improved public health due to their beneficial mild exercise aspect.
 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