Dynamo lighting. Why and how

A few years ago I wrote a post about dynamo lighting on a budget. A few things have changed, one of which is Brexit, which means that purchasing cheap ready build wheels and lights from Germany is largely no longer an options for people in the UK. So time for an updated post. 

Why run dynamo? what's wrong with battery lights

If you're someone who just nips out on a sunny afternoon, then this probably isn't for you. If you ride all year round and cycle for transport and commuting as well as longer rides then here goes.

• Dynamo lights are always available, either at the flick of a switch or via a built in light sensor that switches them when the light levels drop. This is useful when heading through bridges, tunnels or even on a ride with lots of tree coverage
• You don't need to remember to charge them or worry about batteries dying
• They are bolted to the bike, so you don't have to take them off at end of your trip.
• They generally have a more effective and focussed light spread than a lot of battery lights which just spray light everywhere.
• On longer day rides with the right extras you can charge phones and battery packs

Oh and Dyno lights have a bit of trickery inside which keeps them on for a few minutes after you stop. This is so you still have light if waiting at a junction, and is known as a standlight.

That sounds great. How do I get it?

You need three things. A wheel with a dynamo hub, a front, light, a rear light and some cable to connect them.

For hubs there's 3 options.

• Base Shimano hubs are cheap and reliable but a bit on the heavy side. £30-40 quid
• SP are good, mid range and light. £75-£100
• Son are high end but very well engineered. £250 or so.

Decathlon sometimes have basic ready built wheels. That can be a good option if there's any in stock, otherwise it will be a case of getting an online or local shop to build you a wheel or build it yourself

If you have a Brompton, then there is a dynamo lighting kit you can buy with all the bits.

I have a Shimano hub on one bike, and an SP PV-8 hub on the other. 

A SP PV-8 before building into a wheel

The same hub built into a wheel and on the bike

As for lights. Stick with Busch & Muller. It's the most widely available brand in the UK. Axa and Spanninga are also decent quality lights. Again Son Edelux are fantastic, but expensive.

Dynamo lights are usually measured in Lux which is better than lumens. 

Lumens is the amount of light a lamp produces, but just everywhere (like a house lightbulb). 

Lux though is the light output measured onto a square metre. Most dynamo lights are made to german SvTZO standards and have directed & focussed beams. It is the focussed area of the beam which is measured in Lux

<40 lux is good in urban and lit roads.

High as you can for unlit roads and paths. Mine is 80 lux and it's superb for riding along unlit roads and tracks. 

A basic front light will cost from about £25, and a 60-80 Lux will be around £50.

My front light is a B+M Cyo Senso

For rear lights, again you won't go wrong with Busch & Muller, Axa or Spanninga .

You can get lights to fit a rear rack, seatpost, or even mudguards and stays. £20 will get you a decent light.

My rear light. A Spanninga Elips

And it on the bike and illuminated

Putting it all together

It's very simple to put all this together and make it work. the front lights are pre-wired.

You'll need some 2 core speaker/auto cable & some 2.8mm male spade connectors (Halfords calls them audio connectors) and a crimping tool if you want to make your own wiring to the rear light, or you could buy a ready made cable with connectors. Crimpers & connectors are cheap though.

1. Fit a rim tape (velox cloth is best) and tyre/tube to the wheel and fit to the bike.
2. Fit the front light to the bike.
3. The hub comes with a plug in connector remove it & push the wires in from the front light into it and plug into the hub.
4. Spin the wheel & turn on the light and bingo!
5. Measure a length of cable, and crimp male spade connectors to each core at each end ( 4 in total)
6. Connect the cable to the short tails on the front light, and to the rear light, carefully making sure you keep the polarity (+ to +. - to - )
7. Spin the front wheel, and both the front and back light should light. If the rear doesn't, then carefully check to make sure you haven't crossed the connections.
8. Once it's working fit the rear light to the bike, and secure the cable with cable ties. Electrical insulating tape will do a fine job of weatherproofing the connections.

Link to the Shimano generator fitting & wiring instruction (PDF)

This is a really comprehensive guide to dyno lights with shots of the lights in action