For anyone who relies on their bike for commuting, utility cycling, or cycle touring, dynamo lights are probably the best upgrade you can make. No more forgetting to charge your lights, or getting stuck after dark, without lights.
With dynamo lights, as soon as the wheels start turning, your lights are on. It really is as simple as that!
Lights to see with
With cycling, there are two kinds of lights: lights to see with, and lights to be seen. If you only ever ride well-lit roads, and never ride anywhere completely dark, then all you need are lights to be seen.
However, if you’re thinking of cycling on dark rural lanes, through unlit parks, or similar, you’ll want better lights. You’ll want lights to see with!
Watts, lumens and lux
In simpler days, lights were mainly rated in watts. That was actually an indication of how much energy a light used, but mostly correlated with how much light it gives. It’s extremely rare for cycling lights to be rated in watts, and most lights are now rated in lumens.
The exception is dynamo lights, which are usually rated in lux. What’s the difference, you ask? Lumens measure the amount of light emitted at source, while lux measures the amount of light on a set area. Of the two, lux is by far the better, and more accurate measure.
One lux is equal to one lumen per square metre. What this means in practice is that lux tells you how much your headlight will light up the road ahead of you, while lumens simply tells you how much light it produces.
A healthy dose of scepticism
I really don’t care if the webshop you bought your battery light from claims it’s 10 000 lumens. The sad truth is most lights, especially non-branded lights, make absolutely ludicrous claims. Most battery lights now use Cree T6 XM-L LED chips, and the amount of light that outputs varies considerably. For starters, not all chips are of equal quality, and the driver circuit that controls the chip makes an enormous difference. On top of that, outside temperature will also affect it.
A T6 XM-L chip typically outputs anywhere from 700 lumens, to 1 100 lumens, and the output of the same light can vary. As a result, I always work to the minimum, and treat a T6 XM-L chip as capable of 700 lumens. However, you’ll see such lights advertised as supposedly 2 000 lumens. When in doubt, count how many Cree XM-L T6 chips the light has, and multiply that by 700, to get a more accurate lumens rating.
Battery lights are brighter…
…but that’s just one part of a complex picture. Dynamo lights are limited by the power a dynamo can supply – typically 6V and 3W, though that can vary considerably. I used to ride with a 5 x Cree XML T6 battery light – that’s 3500 lumen! It was so bright that cars would dip their lights before rounding a bend.
However, practically all battery lights “waste” light. My monster light lit up everything ahead of me, and 180 degrees to the sides, and even the branches overhanging the lane. It also caused so much light to be reflected back that it ruined my night vision.
Dynamo lights are better
Dynamo lights that conform to the very strict German StVZO (Straßenverkehrs-Zulassungs-Ordnung, or Road Traffic Licencing Regulations) simply use the available light far better. Light isn’t wasted, but is concentrated just where it’s needed. When correctly positioned, such lights (unlike battery lights) won’t dazzle oncoming traffic, either.
The Fischer 70 lux scheinwerfer
A 70 lux light gives enough light to ride at my normal daytime pace, even along otherwise completely dark rural lanes. The Fischer has a tightly focused beam, visibly broken into two parts: it illuminates the road right in front of, and either side of your front wheel, and also lights up the road for easily 50 metres ahead.
The beam is about a standard car lane wide. As someone who loves an all-night bike ride (see Darkmoor) and with years experience of pitch dark winter commutes, I can confidently say that I’m very happy with the amount of light the Fischer delivers.
I tried taking photos of the light, but I’m afraid my camera isn’t good enough. However, I can assure you that this light is bright enough for otherwise pitch dark lanes.
All dynamo lights will flicker at very low speeds (basically walking speed) purely because the dynamo isn’t spinning fast enough. The Fischer is no exception here. However, it seems to deliver a steady beam at lower speed than my old light, a B&M Lumotec OQ2 Luxos, could manage.
A standlight is exactly what the name suggests: a light that keeps shining while the bike is at standstill, for example, at traffic lights. I read reviews bemoaning the supposed feeble standlight of the Fischer, but my experience is different.
My old Luxos light had 3 small LEDs for the standlight, but the Fischer uses the main LED, running at a lower intensity. It’s claimed the standlight will remain on for around four minutes, and while I didn’t exactly time it, that seems right to me. The standlight on the Fischer is better than that of my old light, and certainly not feeble.
The Fischer has a hardware switch to flip between one of three modes: off, on, and auto. When set to auto, during the day the light will turn off automagically, and when it gets dark, it will turn on by itself (provided of course the wheels are turning).
Again, I read reviews saying the sensor is overly sensitive, causing the light to momentarily switch off when you ride under streetlights. I deliberately did that to test it, and the light remained on all the time, even under bright streetlights, while set to auto.
Products reveal their true quality over long periods of time, and I’ve only had the Fischer for a few days. However, the construction seems solid. The body is plastic, with an aluminium top that doubles as heat sink, to dissipate heat generated by the LED chip.
I could not see any obvious water ingress points, but time will tell in the long term.
My old dynamo light costs £190 to buy, though I must point out that it has integrated USB charging, which the Fischer doesn’t have. However, there are very cost-effective ways around that. My old light is a 70 lux light, but capable of 90 lux for short bursts, and the Fischer cannot do the 90 lux bursts, so I’m not quite comparing apples with apples here.
However, the Fischer is only £30, which is massively cheaper than anything else delivering remotely close to the same light output! In my view, for a 70 lux dynamo headlight, you simply won’t get better value for money.
It’s not all moonshine and roses though: the light pattern cuts off quite sharply at the edges, and on rural lanes with sudden, sharp twists and turns, that means at times the light isn’t always shining where you’d like it to. This is a mild annoyance, rather than a critical failure.
Despite that mild annoyance, I can easily award the Fischer a five-star rating.