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Questions on SON dynamo hubs

Find all the questions related to SON dynamo hubs.

If a hub dynamo causes a rattling noise, its axle is not clamped well in the fork. The reason may be sluggish threads that lack grease or wrongly fitted small parts. Please follow the instructions for the skewer or quick release or ask a specialist to show you how to mount the front wheel.

All current hub dynamos do not have a predefined sens of rotation. For the SON 28 Klassik (year of manufacture until 2011), the connections must be on the right-hand side so that the cover screwed into the housing does not unscrew.

This is possible without any problems with a suitable axle adapter (see Axle-Adapter 12mm To 9 Mm QR - Black), but of course only with a 100 mm clamp width.

The rated power of a dynamo headlight is typically 2.4 watts and the dynamo supplies 3 watts. The remaining 0.6 watts are for the rear light. However, a high-quality LED headlight can easily handle 3 watts and shine brighter. This was not possible with lightbulbs.

Nominal values are 6 volts and 3 watts and are achieved at moderate speed (depending on wheel size and generator). However, the real values depend greatly on the electrical load. Without a load, higher no-load voltages also occur. When driving fast, you can draw significantly more power with a suitable load.

Like almost all hub dynamos, a SON hub dynamo supplies alternating current. In addition, none of the poles (spade connections) are grounded, so that the plugs of the SON hub dynamo can be reversed at will.

If neither the headlight nor the rear light shine, this is usually not due to a faulty hub dynamo. In this case, it makes sense to carry out a systematic troubleshooting. To find out whether the hub dynamo is still delivering current, it is recommended to carry out a short-circuit test: When the wheel is spinning, the spade contacts are shorted with a screwdriver. The wheel then becomes more difficult to turn and brakes. When the short circuit is interrupted, small sparks appear.

Either the skewer was not fitted correctly or the hub dynamo has become sluggish. Please check if the connections on the hub dynamo or the connections on the cable are damaged as soon as the axle is mounted well in the fork.

The power input/difficulty of running a hub dynamo can hardly be felt just by turning the axle. It is best to spin the wheel normally when mounted and observe the behaviour. When lights are switched off, the wheel, when turned with momentum, should make a few turns. If it stops already after one full revolution, there is probably a malfunction. Please contact us to discuss your problem together.

New deep groove ball bearings have approximately zero play. In the course of long use, this can increase in the range of hundredths of a millimeter. A small movement to the left and right can then be felt on the rim. If this movement becomes clearly visible (at more than about 0.2 mm), the bearings should be replaced by SON. But even if you continue to drive with bearing play, no damage occurs.

SON hub dynamos are equipped with grooved ball bearings, sealed on both sides and lubricated for life. They normally operate for tens of thousands of miles without maintenance and do not need to be greased or adjusted. If they are defective, they are replaced by our SON partner.

For average use, the materials used in the SON hub dynamo are sufficiently corrosion-resistant. In case of intensive year-round use and exposure to salt water, it is advisable to treat the tension axle and the hub shell with spray wax before each winter.

A lot of grease on the 5 mm skewer can clog the pressure compensation system. For corrosion protection, however, a slight film of grease or oil or, even better, treatment with spray wax is recommended. The contact surface on the screw head and the thread must be greased in any case.

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