Spoke dynamo
A spoke dynamo is a bicycle dynamo that is powered by a spoke on the front or rear wheel. To do this, a driver of the dynamo is turned over on the wheel , which stands in the way of the next spoke so that it is moved along with it. If you want to switch off the dynamo, you bring the driver back to the rest position so that the spokes run past it.
Layout and function
The driver can have different shapes. In the photo on the right it has the shape of a small arrow that can be folded towards the spokes. The electrical connection of the spoke dynamo can be one or two-pole depending on the version. In the single-pole version, the ground connection is made via the frame, while in the version with a two-pole connection, the wiring for the lighting is done with a two-pole cable and the frame of the bike does not play a role as a ground connection. The double cable routing is necessary for bicycles with suspension forks (if the spoke dynamo is on the front wheel), as these often do not allow any current to flow through the fork mechanism. Two-pole cabling of the lighting system is required on new bicycles for reasons of greater reliability.
Comparison with other types of dynamo
Compared to other bicycle dynamos, the spoke dynamo is more expensive than the classic side runner dynamos and rim dynamos . Its advantage is that it is not dependent on the weather. This is also the case with the hub dynamo , which is maintenance-free and offers higher efficiency. The spoke dynamo has no idling loss compared to the hub dynamo (with hub dynamos ~ 1 W at 20 km / h). In the 3/2006 issue of Test magazine, Stiftung Warentest came to the conclusion that the “spoke dynamo was disappointing. At just 24 percent, it had by far the worst efficiency of all dynamos tested ”. One reason for the poor efficiency of the spoke dynamos is the two-stage toothed belt reduction gear with mostly very simple bearings that have high friction losses. Other tests determined an efficiency similar to that of side runners, but worse than hub dynamos.
There was once a special version of a spoke dynamo that generated 12 V DC voltage. As a rule, spoke dynamos generate alternating voltage just like most other bicycle dynamos .
Spoke dynamos were used to upgrade old bicycles inexpensively, as they can be used together with the existing wheel.
None of the former manufacturers currently produce spoke dynamos anymore; there are only remnants available.
literature
- Michael Gressmann, Franz Beck, Rüdiger Bellersheim: specialist knowledge of bicycle technology. 1st edition, Verlag Europa-Lehrmittel, Haan-Gruiten, 2006, ISBN 3-8085-2291-7
- Fritz Winkler, Siegfried Rauch: Bicycle technology repair, construction, production. 10th edition, BVA Bielefelder Verlagsanstalt GmbH & Co. KG, Bielefeld, 1999, ISBN 3-87073-131-1
Individual evidence
- ↑ Stiftung Warentest: Test Fahrradlicht test 3/2006.
- ↑ www.veloplus.ch (PDF; 115 kB.
- ↑ www.pdeleuw.de: Bicycle lights .