Three Great Hub Dynamo Lights Compared

I forgot how much I enjoy riding in the dark. The short daylight hours of the Pacific NW winter often catch me out after dark. Unfortunately, in my excitement I managed to destroy my B&M Cyo dynamo light in a little crash on the Chuckanut Ridge Trail. The plastic light mount cracked in half (not uncommon, apparently) and the wires were ripped from the connectors, leaving me in darkness on the trail. I used the small amount of light from my GPS to walk out of the trail back to Cleator Road and then navigated the 8km home by the cloud masked light of the moon and stars.

Subsequently, I got in touch with my friends at Intelligent Design Cycles (IDC) and they hooked me up with two new front lights to test out – the Dosun U1 and Hermann H-One S. I’ve been switching back and forth between these lights out over the past few weeks on city streets, logging roads and single track, trying to decide on my favourite.

I’ve found that comparing lights is pretty subjective. Their usefulness depends on terrain, speed and a bit of personal preference. Taking beam shape photos is tricky and yields inconsistent results, so I’ve decided to skip that. I’ve assessed subjective build quality, brightness, beam shape, versatility and overall value. I’ve tried to ignore advertised LUX ratings and I don’t care about German StVZO standards (I found this definition amusing). Also, this guy has already covered all the really geeky stuff for these lights in case you’re really interested.

B&M Lumotec Cyo 60 N+ Dosun U1Herrmann H-One S
Price$110 USD$75 USD$65 USD
Weight (inc bracket)100g130g120g
Dimensions52 x 52 x 66 mm50 x 58 x 64 mm53 x 103 x 44 mm
Constructionplastic with LED heatsink at the rear, rotary On/Off switchsturdy, nice looking aluminum housing with steel mounting bracket, waterproof On/Off buttonsturdy aluminum rear construction with plastic front side, On/Off slider switch
StandlightReally bright, up to 6 minutesdaytime running lights only, not very brightdaytime running lights only, not very bright
LED?Cree XP-E?Cree XP-E?
Beam ShapeDecent round shape with good near / far field transitionVery round shape with excellent near / far field transitionSlightly trapezoidal shape with abrupt transition at the edges

Busch & Muller Lumotec IQ Cyo N+

Overall, the Cyo is a good light. It’s really bright at low speed, with a nice transition between near and far field beam shape. The stand light is much brighter than other dynamo lights, making it easier hike your bike when you need to.

My two biggest complaints about the Cyo are the price and the plastic. At nearly twice the price of the other two lights, I’d expect a superior build quality. Unfortunately, the Cyo has a plastic mounting hole which is not well supported, so any significant force from the side will put a lot of stress on the plastic mount. In my case, this caused the light to snap off when my handlebars twisted around. Others have mentioned the same problem on forums.

Another complaint I have about the Cyo is that it is poorly sealed. Shortly after I bought it, I started noticing condensation on the internal reflectors. I dried it out in the sun, but the condensation came back every time I ride in wet or humid weather. It seems to degrade the quality of the light and beam shape.


Busch & Muller Lumotec Cyo 60 N+ with standlight may be bright, but it’s not robust.

Dosun U1

The first thing that struck me about the Dosun U1 is the design and build quality for the price. The sturdy aluminum enclosure looks and feels really high quality. It’s definitely an upgrade from the plastic on the Lumotec Cyo and a great deal at $75. It’s a little bit heavier than other dynamo lights, but I am not counting grams on my steel frame tank bike!

The U1 features a waterproof On/Off switch and rear standlight connection. The daytime running lights are not something I need, but they are useful for putting the bike in the shed at night without stumbling around. They also provide enough light on dark trails if I need to stop and climb over a big log or something.

I prefer the U1’s beam shape, softer light colour and brightness over the other two lights. The transition from near to far field is really smooth. I found I didn’t need to readjust the up/down angle for this light nearly as much when switching between fast roads and technical singletrack.

Tour In Tune-20140217-053
The Dosun U1 comes in a slick and sturdy aluminum enclosure.
Tour In Tune-20140217-052
The internals of the U1 light are well-sealed from the outer elements. The daytime running lights also serve as a basic standlight.

Hermann H-One S

At first glance, I didn’t like the elongated shape of the H-One S with it’s integrated reflector. However, I’ve decided it looks fine once installed and the taller shape puts the light up higher allowing the light to shine over the front tire a bit more than the others.

The H-One S has an aluminum rear construction which serves as a heatsink for the LED. It also makes for a sturdy build quality. The brightness is on par with the other two lights, but the beam shape is not quite as smooth. It’s slightly trapezoidal, with brightness dropping off quickly at the edges. It also lacks the long distance illumination provided by the Dosun U1. However, the H-One S provides a surprisingly bright beam pattern on the ground ahead, perfect for city riding where ‘being seen’ is just as important as lighting the way.

At just over half the price of B&M Cyo, the H-One S is certainly punching above it’s weight. It performs surprisingly well and would certainly be more than adequate for commuting and most riding in general.

Tour in Tune-20140226-110
The Herrman H-One S with integrated reflector sits up higher than the other two lights.

Final Thoughts

In my opinion, all three of these dynamo lights will do the job for night riding in both city streets and backroads. What sets them apart is the build quality and beam shape; the U1 outperforms in both cases. After getting stuck in the dark in the woods with my broken Cyo, I’ve realised the importance of having a bright, rugged front light (and a battery powered backup light in my bag).

These lights may be no match against the blinding, sun-like brightness of my battery powered Xeccon light, but that is simply a limitation of hub dynamo lights in general. On the other hand, the battery on my Xeccon light only lasts about 3-4 hours. Dynamo lights are much more practical for touring, commuting and most off-roading. For most of the riding I do, I prefer the simplicity of dynamo lights and not having to think about recharging batteries before a ride. For ease of use and reliability, I think the Dosun U1 will be guiding me through many dark winters to come!

DISCLOSURE: I bought Cyo at full price in Jan 2013 and received the U1 and H-One S from IDC free of charge for evaluation purposes. I don’t have any business affiliation with any of these companies.

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