The opinions expressed in the studies are those of the consultant and do not necessarily represent the position of the Commission.
According to the Vienna Convention, a cycle is a vehicle with at least two wheels that is propelled solely by the muscular energy of the person riding on that vehicle, in particular by means of pedals or hand-cranks. Furthermore, the Convention states that a cycle shall: a) have an efficient brake, b) be equipped with a bell capable of being heard at a sufficient distance, and carry no other audible warning device, and c) be equipped with a red reflecting device at the rear, and devices ensuring that the bicycle can show a white or yellow light at the front and a red light at the rear .
In addition to the abovementioned "conditions for the admission of cycles to international traffic", some countries such as Germany and the Netherlands have supplementary regulations regarding mandatory equipment to ensure cyclists' visibility. Examples are:
In some countries (the Netherlands, for example), standards for accessories such as children's bicycle seats have been drawn up. These standards include requirements and recommendations regarding seat attachment, dimensions, footrests, and protection against feet coming into contact with the spokes  .
In some European countries, cycle helmets have become mandatory in the last few years. In Malta, cycle helmets became mandatory for all cyclists in April 2004. In Sweden, cycle helmets became mandatory for children up to 15 years of age on January 1st 2005. The same group of cyclists has to wear helmets in Slovenia and the Czech Republic. In Spain, cyclists have to wear a helmet outside urban areas except when going uphill  .
The definition of precise standards without which the effectiveness of helmets cannot be guaranteed, is a prerequisite for any regulations on the wearing of helmets. Some countries have already set up such norms. The European Directive No. 89/686/EC on personal protective equipment lays down the standards which could be adopted for cyclists' helmets. The provisions for children's helmets, however, still have to be settled .
In addition to the rules which normally apply to all public highway users and in accordance with the Vienna Convention, cyclists are subject to specific rules defined in their national legislation in order to ensure that they can travel safely and easily:
The Vienna Convention prohibits the transport of passengers on bicycles, but enables the Contracting Parties to authorise exceptions. In some countries, the transport of a passenger is allowed only if he is under a statutory age limit (for instance 14 years in France) and if the cyclist himself has a minimum age .
Germany has recently added new elements to its traffic code for cyclists. Since then, cyclists are allowed to ride contraflow in selected one-way streets, and in so-called bicycle streets cyclists may make use of the whole street whereas cars have to stay behind the cyclists. As in some Scandinavian countries, cycle tracks in Germany can be made compulsory only if they meet appropriate minimum quality standard, otherwise cyclists may choose not to use cycle tracks .
Some national legislations provide that cyclists can only ride on a road after a certain age. In Switzerland, a cyclist must have at least the legal age to go to school before he can ride on a road. In Denmark, children under the age of 6 are not allowed to go by bicycle unless they are escorted by a person who is 15 years old or older. In Germany, children must be at least 8 years old with the same provisions as in Denmark. In Poland, children over 10 years must have passed a test to be allowed on a road .