Bicycle lighting#Dynamo systems

A bicycle dynamo ( Swiss High German bicycle dynamo, short Dynamo, also alternator) is a small electric generator, which ensures the power supply to the bike lights by twisting while driving.

Typically it is a small single-phase alternating current generator in which a permanent magnet is driven by movement of a wheel. The magnet rotates in a fixed stator winding, where it induces an alternating voltage. In modern hub dynamos is the populated with permanent magnet rotor rotates around the outside of the inner stator.

Bicycle dynamos are mostly unregulated, however, stabilize the voltage to some extent by the inductance of the generator winding at increasing speeds (and thus increasing frequency ) forms an increasing inductive series resistance. Since the voltage is strongly depending on the load by the ohmic resistance of the coil, reduced load results (eg by a defective headlight ) to power surges, which can have a burn through the tail light bulb result.

Depending on the model, bicycle light machines often extremely high efficiencies. Evidence of a good efficiency are low speeds (large friction wheel hub dynamo, roller dynamo ), as well as ball - friction bearings instead.

In Germany bikes until July 2013 in accordance with § 67 traffic regulations were required to equip with a dynamo. It must have a power rating of at least 3 W, and a nominal voltage of 6 volts. After a change in the law, the use of battery or battery - powered Beleuchtunseinrichtungen is now an alternative.

Forms of bicycle dynamos

• External Dynamo
• Hub Dynamo
• Spoke Dynamo
• Role Dynamo / roller dynamo
• Rims Dynamo