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Most recently updated: 11/05/2013 – SG

Of Dynamos and Bike Lights, or How I Learned To Stop Worrying and Love The LED

Let’s talk dynamos.

This is a big topic of much interest to lots of cyclists, and seems to inspire a lot of writing from everyone; myself included.  About Dynamos and Dynamo lights, this is a brief synopsis of what I have learned;  brief as I can make it.

First thing – everything about dynamos is decided in Germany.

Why do we care?

Because all the good gear is made for the German/Netherlands market. There are roughly 120 million people in the Netherlands, Germany, and Denmark.  As of 2008, roughly 10~37% of them bicycle as a matter of course; compared to the US average of 1~3%.  (reference)   That’s approximately 15~30 million bikes, and they are required BY LAW to have dynamo lighting. BY LAW.  

Out of necessity some very specific laws surrounding bicycle lighting have evolved, called the StVZO/TA.  The STVZO is a little insane to read and is bizarrely specific in places – but I suppose when you have roughly 15~30 million cyclists it makes more sense.  For the purposes of my little blog entry I’m going to grossly summarize and highlight a few relevant points.  (Just… shut up Fred)

• Bicycles are required to have lights front and rear.
• Rear lights are required to be red
• Front lights are required to be white or yellow.
• Front lights shall not be permitted to shine in the eyes of oncoming traffic.
• All bicycles over 11kg (23.2lbs) are required to have dynamo powered lighting.
• Front lights must use 2.4 watt bulbs (-20% to +10%) on 6 volt systems.

If you want a more in depth summary READ ON – those are just a few highlights.  But let me hit that big point again in case you missed it…

• All bicycles over 11kg (23.2lbs) are required to have dynamo powered lighting.

That means there are 15~30 million cyclists that are bound by law to have dynamo driven lighting.  That line right there, MAKES Germany/Netherlands the target market.  Period. So… what does that mean for us? It means that what happens in Germany/Netherlands effectively sets the tone for dynamo manufacturers around the world.  Dynamos and dynamo-driven products the are being designed foremost to adhere to the standards of the STVZO so they may be sold to the German/Netherlands market.  These products are later repackaged and resold to the rest of us after the fact.  Why are lights capped at 2.4W?  Because the STVZO says so. Why do we use asymmetrical beams for lights?  Because the STVZO says so. Why do hubs saturate at 15kph?  Because the STVZO says so.

Though we in America aren’t bound by the STVZO manufacturers know that to violate the STVZO is to ostracize themselves from a market of roughly 15~30 million cyclists.  Nobody is willing to walk away from those kinds of numbers. These aren’t necessarily terrible standards – there is some pretty great stuff to come out of it.  But all the above also adds up to mean your options getting into the dynamo game are somewhat limited, often expensive, and most of the good stuff has to be ordered directly from Europe. Let’s talk gear.

Dynamo Hubs

There are effectively two ratings of hub dynamos – 3 Watt and 2.4 Watt. (BTW – all this stuff is 6 Volts aka 6V)

3 Watt dynamo hubs are the most common.  They’re rated to generate 3 Watts at around 9mph on a 700c wheel.  That is enough juice to power a 2.4W headlight and a 0.6W tail light (STVZO Compliant!).  Common hubs in this category are  Shimano Alfine, Shimano Nexus, Supernova Infinity 8, and SP Dynamo’s PD-8 to name a few.

The 2.4 Watt dynamo is sort of a new thing.  As you might have inferred they’re only rated to generate 2.4 Watts (at around 9mph on a 700c wheel), but they have been given special dispensation by the STVZO so are still compliant.  While it’s true that these hubs generate less electricity, depending on the brand they can be anywhere from 50 ~ 200g lighter which is significant. My knee-jerk reaction is to say 3W doesn’t feel like much to work with – dropping to 2.4W seems like a big deal.

However, LED technology continues to evolve and become more efficient, requiring less power to do the same (or better!) work.  This means  when paired with the appropriate lights riders can use these lighter-weight/lighter-drag dynamos to achieve to similar effect.  Combined with the STVZO rubber stamp I think we’ll continue to see these hubs grow in popularity.  That drop to 2.4W may be less of a big deal after all.  Common hubs in this category are Schmidt SON Delux, the Supernova Infinity S, and theSP Dynamo’s SD-8.

A point of note – dynamo hubs feel “notchy” in the hand, but generally feel pretty okay on the bike.  Generally.  There may feel some very minor vibration in the bars while pedaling.  This usually gets better over time but the notchy feeling is how the electricity is generated and it’ll never go away completely (though you can get close).  Remember, a very small part of the rotational inertia is being diverted to generate electricity for the lights.  That notchy feeling are the magnets and poles being drug against one another to generate current.   In practical terms this means more electricity you draw, the more you need to generate, the more drag is involved.

With the lights off I forget I even have a dyno hub most of the time, and I feel it a little when the light kicks on.  The more stuff asking for electricity, the more you feel it. So yes it’s a bummer that generating more electricity puts more drag on your bike but as I said before, LED technology is perpetually evolving and getting more efficient.  An LED bulb needing 2.4Watts to deliver 60 LUX this year may only require 1.8 Watts to do the same work next year.  By using more efficient LEDs we can look forward to using lighter dynamo hubs that exert less drag.  Which leads into the next part of this.

Lights

There are many different factors to consider with lamps, factors that I didn’t realize mattered until I started comparing them.

• Luminescence (how bright – measured in Lumens or LUX)
• Beam Pattern (Asymmetrical or Symmetrical)
• Light Color (Cool white, yellow, or clear)
• Standlight (How long the light stays on after you stop pedaling)
• Mounting Options
• Artifacts

In the land of dynamo lights, beam pattern is the thing that manufacturers are concerned about most.  Lights that are to be STVZO compliant must ensure that light aimed at the ground 5 meters away not spill light above the “horizon” (or into the eyes of oncoming traffic) more than 2.0 LUX.

That is very very little light, making this a pretty strict standard to meet. In response, manufacturers have adopted a shaped (asymmetrical) beam that focuses the light downward to provide a hard “horizon” similar to car headlights.  Asymmetrical beams are generally better for pavement and bike paths, and nicer to other cyclists and motorists like the STVZO intended.

Asymmetrical beam pattern

This is a standard symmetrical round-beam like a flashlight uses.  There is less light on the path specifically, but more light in the surrounding areas.

Symmetrical beam pattern

Symmetrical lights are better for off-road since they highlight overhead things like tree branches and ninjas and shit. They’re not STVZO compliant but presumably you’re in the woods with this kind of light so oncoming traffic isn’t really a thing.  The thing that makes them great in the woods are what makes them illegal on pavement in Germany/Netherlands – their tenancy to spill light all over the What.

The Dynamo

Get a (Shutter Precision) SP PD-8 /PV-8 or Any Shimano dynamo hub

All the guts of the Shimano dynamos are the same, it doesn’t matter which one you get.  They’re all 3w/6v hubs, they’re a wee on the heavier side of things but they roll really well, they’re very durable, and at $125~ the price point is solid.

The (Shutter Precision) SP PV-8 are almost – literally – half the weight of a Shimano hub, are also 3w/6v hubs, and come in lots of colors.  They’re also around $125~ each which is a pretty sweet price point.

Get the Shimano or the SP.  You won’t be disappointed.

If you want to compare them to the Schmidt SON Delux – The SON is a 2.4 watt hub, the SP is a 3 watt hub.  The SP weighs 15 gr more (big whoop) puts out more juice, and is $120 cheaper.  You do the math.

I have SP’s on all my bikes and like them a lot – they’ve performed very well.  My gut feeling says they may not be quite as durable as a Shimano dynamo hub, but I’ve never run either one to ground so who’s to say.  They both get my stamp of approval and I suspect they’ll get yours too.

If you can afford it – do the Luxos U.  It is BY FAR the best fucking dynamo light made to date.

That’s right, it deserves the F word.

At $200~ they’re a wee on the spendy side (though not the most expensive at all), and they are worth. every. nickle.  They are rated from 70 to 90 Lux which is brighter than most other dynamo lights out there.  They have a kick ass standlight – in fact they also have an internal battery cache that’s better than pretty good.  True story, I pedaled to my neighborhood bar one night about a mile away.  When I got there I realized I’d put my dynamo wheel on backwards and had forgotten to plug the dynamo in.  I’d ridden there in the dark on cache battery and didn’t realize it until I’d arrived.  (I knew it was dimmer but thought I just had to re-point my light or something).  Very impressive.

Other things - color is perfect, pattern is perfect, they have a little logic in them so when you’re going real slow (like in a climb) the nearlight lights light up so you can see what you’re doing close in.  They have a handlebar controller button so you can turn it on, off, or turn it on high with the push of a button.  How great is that?

Also, the U version comes with an honest to god USB charger.  Yes, it will charge your phone or GPS.  In fact, it will charge your gear while it puts out light if you ask it to (but you’ll feel the drag and the light gets pretty dim).  Still, that’s a feat nobody has ever done.  Personally I only do one or the other, but your call.

I have been nothing but impressed with it.  If you read the link I posted, Peter White won’t shut up about it either.  Here are a few pics.

Do the Busch & Müller Lumotec IQ Cyo N Senso Plus aka the Cyo 60.

It’s a brighter version of the 40 LUX IQ Cyo R that I tried above.  It’s a 60 LUX light with an asymmetrical beam of neutral-colored light.  The Cyo 60 doesn’t waste any effort into trying to beef up the nearfield like it’s cousin the Cyo 40, and got 20 LUX brighter in the process.  It also has an effective cutoff switch which the Philips and the E3 did not.  At $70 it’s also one of the more affordable lights out there.

If you need a mountain dynamo light…

You should consider the Klite mountain dynamo light from Kerry over at K-Lite.  I am very impressed with his offerings.  My last review of his stuff is so out of date I’ve pulled it completely.  Go over and take a look at what he has.  Find him on Facebook if you want more up to date stuff.  He does some really interesting stuff.

If you need a battery light…

you should consider the Philips Saferide 80

We’ve nicknamed it the Hand Of God.

It looks like the sucky Philips Saferide 60, but it’s not.  It’s bigger, it’s battery driven, and it puts out a whopping 120 LUX of netural-colored light.  It runs on 4x rechargable Double-A NiMh batteries and has (among other qualities) a USB battery charger built directly into it!  You need merely plug into the back of the light and it will charge the AA batteries in place.  Way to think it through Philips!  (If you have the Luxos U above, the Luxos U will charge your AA batteries in this charger.  Mind = blown.)

This thing is awesome.  It delivers just a fantastic amount of light.  GREAT GOBS OF LIGHT.  What this light lacks in intensity per square inch, it makes up for in sheer quantity and throw.  It simply dwarfs other lights. Strangely, it has a STVZO light shape which would normally disqualify it for mountain duty but it puts out so much light, it basically doesn’t matter.  It works great in the woods.  The run time on this is good too.  I haven’t done proper benchmarks but I want to say I’m getting betwen 5~7 hours for a full discharge on low, and between 2 ~ 2.5 hours on high.  Physically it’s a big hurkin light.  Looks dumb as hell to be honest – like you strapped a search light to your handlebars.    But it performs very well and the handlebar clamp is of quality design.

I was pleasantly surprised to find that, despite the size and weight the Philips 80 doesn’t do a lot of wandering around on the handlebars.  This is the big complaint of the ever popular Niterider lights who are also quite heavy and bright.  Once it’s on, it’s on and you’re good to go. One small Con – it will not under any circumstance fit around a 31.8 bar.

You’ll need to purchase a light mount adapter of some sort.  THE FSA 31.8 BLAH BLAH BLAH WORKS VERY WELL.

Battery Charging:

Though the Luxos U has a charger and I am gushing about it, I think the below still holds true so am keeping it in here – Ed

The Saferide 80 has an integrated charger.  Your phone has a charger.  Your GPS has a charger.  Your MP3 player has a charger.  How do you charge the batteries?  You have a hub that generates electricity – theoretically it should be possible.  It’s here I’m still working out the details.  Originally the idea was to charge my devices directly with a dynamo driven USB charger like: The Charger – Tout Terrain’s “The Plug II” It sits inside the steerer tube and acts like a replacement stem cap, the guts brilliantly hidden away and protected.

The Problem?

The charger only works if you can maintain speeds over 9 mph on a 26in wheel, or 11mph on a larger 29er wheel.  If you don’t stay above those speeds and sustain them for long periods of time, or if you merely hovered around that speed, the charger actually draws more juice then it produces going in and out of charge mode, resulting in a net loss.

Bummer. As far as I can tell this is a limitation of all chargers, not just this one. This probably works fine on a road tourer where you’re putting down miles at steady cadence, but if you’re doing off-road mountain touring, cruising fire roads under load, on inclines and dodgy ground, maintaining 11mph for any appreciable period of time on those kinds of roads is pretty difficult.  Your speed is always changing, always going up and down while you navigate this or that.  Sure you might get some flat or downhill stretches, but they go fast.  You invariably spend more time climbing then you do descending, and in that kind of terrain the charger was worse than useless.

Charging conclusions:

1. Direct charging from the hub isn’t functionally effective.  Bike speeds go up and down and you’ll often spend more juice going in and out of charging mode than you’ll gain.  I haven’t tested it yet but my current theory is it may be better to dump juice into a dedicated power pack throughout the day, and then charge your devices from that later.
2. Direct charging from solar panels isn’t functionally effective – yet.  Weather changes, sometimes you’re in good sunlight, sometimes not.  Again you’ll often spend more juice going in and out of charging mode than you gain.  There’s some awesome technology on the horizon re: Graphene that will probably revolutionize solar panels in the future, but it’s 2~5 years out at my best estimates.  Like hub charging, my current theory is it may be better to dump juice into a dedicated power pack throughout the day, and then charge your devices from that later.
3. Direct charging from thermal sources (PowerPot, BioLite) provides some options but they’re a bit cumbersome.  They’re expensive, somewhat heavy, and only work as long as you’re burning fuel (gas or wood) – and the Power Pot only works as long as you have water to boil.  Additionally this means you can’t charge anything until you’re stopped and are cooking something.  Again, dumping into a power pack of some kind seems like the way to go here.

I think charging is doable, but I think overlapping your options and dumping them all into a power pack so you can later charge your devices using steady state current is the only way to effectively make it work.  Dump dyno and solar juice into a power pack in the daylight while you’re pedaling, dump powerpot and biolite juice into a power pack at night while you’re around the campfire.

If you want to buy a battery pack…

The Satechi 10,000 mAh Portable Energy Station is the only one to get.

It is small, it is light, it itself is charged by mini-USB, at 10,000 mAh it holds about twice the charge of most smartphones today (which have batteries between 3200 and 4800 mAh with some exceptions) meaning you will probably be able to charge your phone twice from a completely dead state before it taps out.  It has two USB-outs (a 5v/1A and a 5v/2A – the latter so you can charge iPads and tablets), and at $60 it is very reasonably priced.  There are a lot of power packs out there, and after much research this one is the only one to get.  Some are big, some are heavy, some are expensive, some are light but have smaller charge capacities, some have limited charging ports, some have lots of charge ports but are missing the 2A port to charge tablets, some require special charging plugs or require you plug into a wall to charge.  This is the only one that checks all the boxes.   All others fall short of it and you are wasting your time and money on them, including the Anker which was the closest.  If you can find better, comment here.

Here are some pics.

Anyhow that brings us up to speed.

That’s what I’m running and how I got there.

Lots of reading material if you’re interested.

PETER WHITE

Wouter

http://www.enhydralutris.de/Fahrrad/Goniometer/Tabelle_Scheinwerfer.html

http://www.enhydralutris.de/Fahrrad/Goniometer/AR2008/AR2008.html

http://sweetbike.org/downloads/light.dispersion.details.drilled.down.html

http://sweetbike.org/2011/11/28/2132

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