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Thursday, 15 July 2010

Dynamo Lighting

Dynamo lights were once common in the UK and USA, but have since fallen out of favour as battery technology progressed and people started using bicycles for sport rather than transportation purposes.  In other countries where cycling continued to be a mainstream method of transportation, dynamos remained popular due to their reliability and the lack of need to purchase and rely on batteries.  In Manchester it is dark almost all of the time (or at least almost all of an average adult’s free time) from October to February making lighting essential if you want to stay mobile in those months.  In Germany in particular it is illegal to use bicycles without a dynamo powered lighting system (except lightweight racers).  This means most German bikes come with lights, which is a legal requirement in some other countries and would make sense in most.

I personally prefer hub dynamos to bottle dynamos because they are generally of  higher quality, are more discreet looking and it just seems to make sense to integrate the dynamo out-of-the-way into the hub.  Its a shame they don’t make rear hub dynamos anymore as having two dynamos would open up some interesting possibilities.

The German law requiring dynamo lights has created a market for high-end dynamo systems, many of which are available here.  Sadly information is patchy, making it off-putting to take the plunge.  With some advice from LC, I decided to invest in a Busch and Müller Lumotec Retro Senseo Plus dynamo headlamp, to be driven by my Sturmey-Archer X-FDD hub discussed previously.  The unwieldy name is in part due to the range of options available, bottle dynamo, hub dynamo, light-sensing auto-on/off, stand-light etc.  Mine has the stand-light, an off-switch (hub dynamo version) and the light-sensing auto-on/off features.


The rear of the lamp has a switch, with three positions, basically off, automatic and on.


The underside of the lamp has pins to drive a rear (0.6 W) lamp.  Modern LED lamps are available which are compatible with this arrangement.  This was not well explained in the product information I encountered, so is essentially a bonus.


These are the pinouts on the dynamo hub.  The Shimano ones are essentially the same, save for a variation in shape.  I don’t yet know about the SON or SRAM versions.  Feel free to comment if you know anything about these hubs.


This is the plastic plug which came with the hub, Shimano hubs come with a similar plug, older Sturmey Dynohubs use screws to make the connection much like older loudspeakers.


The ends of the cable attached to the lamp.  The cable is essentially cheap speaker cable.  The ends are partially stripped like with new speaker cable.  All that needs doing is to remove the wire coating, twist the wires into a single fibre and feed them through the plug and fold them over into the grooves.


Polarity is not important, as the dynamo outputs AC (making it not technically a dynamo) so just bung whichever wire in whichever side you fancy.  The reason I have posted this in such detain is that none of this information is given in either the B&M or Sturmey manuals, and so it might be useful to someone.


The light comes on at about 8 km.h-1, but this will be lower for smaller wheeled bikes.  There might be a lower limit for wheel size in order to prevent generating too much power for average dynamo lamps.  Maybe one day I’ll put one on a Twenty and find out.  The stand-light is powered by a capacitor, so won’t be available straight away when the lamp is new.  I’m going to go for a spin tonight to test it out properly.


  1. For a great source of information about dynamos and lights (and to purchase)take a look at
    He's in the U.S., but ships almost everywhere.

  2. I am sure mine comes on when I go slower than 8km/hr... which is... often ;) techy stuff aside, looks great on the Tourist!

    I have never noticed it had three settings, I always thought it was on or off *doh!*

    ah... surely you've given the Tourist a name??? =)

  3. @Mark, Thanks, I'll probably use that in future for reference, although I've had problems actually buying stuff from the US before. The prices are good but then UK customs add VAT onto it and charge you a fee for the pleasure too. Plus it adds about two weeks to the delivery time.


    Is your Princess the 26 inch wheeled version? If it is I'd imagine that the lamp would come on at a lower speed. I'm really liking the lamp, now all I need is a dynamo rack light for the back and I can be self-sufficient. I'll post info on here if I do; if it works on mine it should work for you too. Thanks for the advice.


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