Dynamo lights are simply lights powered by a hub dynamo located, usually, at the center of your front wheel. As you pedal a series of magnets rotate around a copper coil which generates a current. Wire that up to some lights and you’ve got, in our opinion, one of the most necessary features for not only touring bikes but any non-racing bicycle.
Bikes Need Lights
We design bikes that are ready for touring and lights are a key part of them. Even if you ride mostly in daylight, you still need lights. For example, tunnels sometimes just appear. Along the Fernleigh Track at Newcastle or on Black Sea coast in Turkey or anywhere in Japan. You can not tell from most maps that they are there. Most are not long but going in without lights is mad.
Or, sometimes you are late arriving at your next camp or hotel. It could be for any one of numerous reasons. Imagine this scenario….you don’t know the road, there are no street lights, you are tired, your buddy is up ahead looking around to see where you are. Thank goodness you have lights, and ones that work.
Perhaps you are touring in Vietnam, Sri Lanka, central America or anywhere near to the equator and are surprised to find it is pitch black dark at 6.30pm. In the East Kimberly in mid June it is dark by 5.20pm. Or, it is unseasonably hot and you decide to set out in the dark so as to arrive by noon. You need lights before the sun comes up.
Bikes used in everyday life in cities need lights too. A person who uses a bike daily is going to be riding sometimes while the sun is down.
It is self-evident and we should not need to make the point. However, most bikes sold outside of the few countries that mandate lights (eg Germany) don’t have any lighting system designed into them. It is simply not true that dynamo lights can be added later with as good a result as if they were designed into the bike.
Lights Being on in Daytime is Good for Safety, Especially if You Are in Traffic
With a dynamo you can leave the light on permanently. No batteries or recharging is required. The system is integrated into the bike and you don’t need to remove the lights when locking up your bike. Being integrated, they are not vulnerable to the daily jostle your bike endures. Yet we see virtually no dynamo systems on bikes in Australia, NZ, the US and Canada. If they are so good why are they not on new bikes? The main reason is that lights are not required to be supplied with new bikes in these countries. In addition, authorities mostly ignore the fact that some cyclists are riding after sundown without lights. However just because authorities don’t seem to care is not a reason for us to overlook this part of bike design.
On motorbikes, Daylight Running Lights (DRL) are mandated in many places. The small frontal area of a motorbike has been found to be a reason why they are less conspicuous on the road. Surely this is just as applicable to bicycles.
The best dynamos are in front hubs and have to be integrated into the wheel at manufacture.
So, because of the benefit of having lights on all the time, and the independence of making the electricity yourself, with the exception of specific lightweight racing machines, bikes should all have dynamo front hubs.
Dynamo Lights? Why Not Just Use Rechargeable Battery Lights?
There are some very bright rechargeable battery powered lights. But they are no good when you can’t recharge them which may be the case when you are on a tour. Even in town, recharging is another chore. And then, with battery lights, you have to make sure they are not stolen.
Whilst a dynamo has a small amount of drag, recharging batteries daily, over the years, is a bigger one. With a dynamo you just leave the lights on permanently and forget about them.
Lumens, Lux and Light Projected onto the Ground
Lumens is the measure of all the light coming out of a headlight. Lux is the measure of light in the centre at a spot on the road a specific distance away. In the European bike light standards, a distance of 10 meters is the base point. So lumens and lux are quite different things. The ‘aftermarket’ for bike lights, including their on-line retailers, usually only talk about lumens. They imply that the more lumens the better. There is generally no attention paid to the shape of the beam on the ground.
The European standard defines the ideal shape of a light beam. Lights are designed to throw the light onto the road. This means focused cut-off optics like a car’s headlight, which keeps the scattered light to a minimum. From the side and from above the cutoff line of sight (say, an oncoming driver’s or cyclist’s head), the light is nothing more than a glowing spot. The beam isn’t super-wide, but covers the bike’s path well.
USB Recharging Ports
As cyclists we are using our own energy to move along. It is natural for us to want to also capture some of this energy to provide charge not just to our lights but to our devices. In principle it is such a simple idea. However, in practice it is not. The various products on the market (including some like AXA Luxx70 that have been withdrawn from the market) are underwhelming.
The fundamental limitation is the international standard of 6V3W which restricts the amount of power that dynamo hubs are allowed to produce. The restriction dates to when we had incandescent bulbs. Imagine going downhill in the dark, gathering speed, and the light suddenly goes out! The upshot has been recharging systems that provided so little power that they did not work at speeds under 12km/h and did not charge a device if the bike lights were turned on.
Vivente and Bezier have been working together to solve this problem. As at mid 2021 we are testing a new hub that does comply with the standard but also does supply enough power to simultaneously run the lights, and add charge to a smartphone that is turned on for navigation. The system works at low speeds (7-8kph) and stores power in super capacitators rather than lithium batteries. Lithium batteries only handle about 500 recharges which, on a bicycle, means a lifespan of only 1-2 years. Super caps last for a virtually unlimited number of recharges.
This new system comes with a controller that is mounted to the bike frame and a phone app.
Several new features are being designed into this system. For example, a headlight that can run at a low level of brightness for urban and daytime use but can run at a very bright level for dark nights in the bush. Another feature will be capturing the extra power generated in fast descents.
The new power system will be standard on Rohloff models which are scheduled for production in late 2021.