Powering Your Gadgets For Endurance Races

Most people who do long-distance bicycle endurance racing are somewhat obsessive/compulsive about their gear. That’s putting it kindly. I’m definitely no exception and my blog is littered with posts on the most esoteric aspects of bike setup, equipment etc.

Providing power to your gadgets (GPS, lights, phone, trackers, etc.) during races is an area we spend a lot of time on, and has provided endless hours of entertainment and frustration over the years. Since my first attempt at the Tour Divide in 2011, I’ve refined my approach—and there have also been sea changes in technologies—so I thought it was timely to put down my journey to hopefully assist others in finding the best solution for their needs, be it endurance racing or just touring.

If you don’t want to read further, here is the 30 second elevator pitch:

  • If all you want to do is to have power for your GPS or phone, don’t bother with dynamos etc. Get a couple of small 5000+ mAh power banks and use these. I’ve run my Garmin 1000 for almost 40 h on one of these—before it had to use the internal battery. 
  • If you are going to be running multiple gadgets and doing night riding get a dynamo and headlight
    • The SON 28 is the best dynamo—but expensive.
    • The Luxos U is great for road riding—particularly because it has the integrated USB converter and a cache battery. Plug and play. Only challenge can be getting it mounted …
    • For mountain bike riding the Luxos is probably too fragile so better getting a K-Lite, Exposure, Supernova or similar.
    • If your light has a USB output (like the Luxos U):
      • Get a Goal Zero recharger with Eneloop 2550 mAh AA batteries and which passes through while charging. You will be able to power your devices when the dynamo can’t and have 4 x AA batteries as well if you need them.
    • If your light does not have USB output:
      • Get the ZZing or Reecharge Powerpack which will convert the dynamo power to USB, and have integrated cache batteries. Alternatively, get the PedalPower Universal Cable and the Goal Zero recharger.  The latter is best if you have extra devices which run on AA or AAA batteries.

I’ve bought most of my gear from Peter White cycles in the USA. His site has excellent information on dynamos and a wide selection of gear.

  • Updated 11/3: Additional details including run times for battery packs
  • Updated 27/2: Included Reecharge PowerPack
  • Updated 17/2: Included ZZing

Dynamos or Batteries?

There are two schools of thoughts. Some—like my racing friend Peter Maindonald—prefer to keep things simple and avoid the hassles by using batteries. This can be a good strategy and works. They use a GPS such as the Garmin eTrex which runs off AA batteries, battery pimageowered headlights, and if USB is required for example to recharge their phone, they often have a battery powered USB converter such as one of these Gomadics (which I use as an emergency backup).

One comment on these AA systems: always go for a four cell rather than a two cell. I’ve found that not all two cell systems work with all devices.

A good hybrid solution is the Goal Zero Plus 10 recharger. This will recharge your batteries so you could get by with 8 batteries and swap them out, as well as providing a USB backup supply. Only problem is that the AAA adapter is not integrated and I’ve lost the adapter (which has to be ordered separately).  Kerry (from K-Lite) advised that the batteries can come loose so I’ve put in some packing foam and a rubber band around the outside to hold everything in place.

For rechargeable batteries, I use the  Eneloop batteries.  These are really powerful (current models 2500 mAh) and in one test I ran my SPOT GPS via USB for 60 hours on one charge off a Goal Zero unit.

The biggest issues with using batteries are:

  • You may run out of batteries—one year the Tour Divide leader ran out of light only hours from the finish and had to bivvy in the desert until the sun came up.
  • The lights are not as powerful as the lithium rechargeables.
  • I don’t like littering the environment with used batteries—hence my preference for something like the Goal Zero. I’ve dallied with solar but the very compact units are just not strong/reliable enough to meet my power needs.

I do a lot of riding in the dark—during the 2015 Transcontinental race I became nocturnal because of the heat and so did most of Italy, Slovenia, Albania and Greece in the dark. Since I also like power independence that meant running a dynamo.


Dynamo hubs have a capacity for 6 volts AC power, but the output is speed dependent. The figure below shows the effect of speed on different dynamos. At slow speeds—such as you get when climbing mountains—they put out very little power which is why (in my view) having some form of cache battery is important. This ensures you don’t get annoying messages like ‘External Power Lost’ from your Garmin 800 GPS.

One question that often comes up is how much drag the dynamo causes. Ed Pickup has the figure below which shows you are typically looking at some 5 watts of drag with the lights on, and one watt with them turned off. When you spin a dynamo hub in your hands it feels much worse than that, but don’t worry: that is just because of the slow speed you are spinning. When riding I don’t notice the difference.


This is another example of drag from the controlled tests on a range of hubs  which is from http://www.ctc.org.uk/file/public/feature-hub-dynamos.pdf.


The biggest hassle of a hub dynamo—besides the expense—is that you also need to get a new front wheel built around the hub. I have had mine done by Tristan’s team at www.wheelworks.co.nz and they are incredible.  During the 2015 Transcontinental Race I hit a hole while descending Mt. Locven in Albania at speed during the night.  Put a massive dent in my rim. Managed to last me another 1200 km until Istanbul. When Tristan’s team looked at it, the only spokes out of tension were those around the dent. I’m sure that any other wheel would have failed and I would have been seriously injured. Don’t scrimp on a good wheel!


A recent development was the Velogical rim dynamo. This is a very nice unit which runs from the flat braking surface of your rim. I did  some tests to see how it compared with hub dynamos for drag. I found that when set up correctly, there was no significant difference between it and my two hub dynamos. The only issue I had was the sound it made—would get annoying after a while—but  I’m keeping it as an emergency backup dynamo.


I have two hub dynamos:

Both have worked without any issues for many thousands of kilometres. The SON28 is much more expensive than the SP and has advantage that the bearings can be renewed without having to return the hub to the factory (which SP requires). This is a bother since if the bearings go you are looking at a complete wheel rebuild given the cost of shipping the wheel to Taiwan.   The SON apparently can last 25,000 km between services and I know a few people who have several Tour Divides under their belts with the same hub. I’ve over 10,000 km on one SP which continued to work fine, although one friend had the bearings pack in at 7,000 km.

If budget is not an issue go for the SON—they are almost three times the pricealmost three times the price of an SP—you won’t regret it. I got mine from Peter White. My SPs came from eBay.

The SON has two ‘blade’ connectors which can be replaced in the field much easier than the SP which has a plastic cover. This site has a good description on how to wire the SON cable.


Front Lights

You are spoiled for choice when it comes to dynamo lights. Everyone has their preference. I’ve had a K-Lite, Supernova E3 and Busch and Muller Luxos U. Sold the K-Lite, kept the E3, and bought another Luxos U.

K-Lite from Australia are probably the most compact light that you can get. imageThey are incredibly bright—1000 lumen—and are designed for off road use. If you are looking to ride only on trails then seriously consider this light. It most definitely is not street legal—especially in places like Germany where there are very strict regulations. Even if there are not regulations against its use, riding on the road with it would likely blind oncoming drivers—it is seriously bright, even at its 600 lumen setting. My only reservation about K-Lites is that the units do not have all the same slick design features of some of its competitors—Kerry uses a 3D printer for a number of elements. However, they are robust, race proven and very fit for purpose.

imageThe Supernova E3 from Germany is also very powerful and NOT street legal in Germany. It has 640 lumen. Larger than the K-Lite, it is incredibly well engineered and has the best mounts of any dynamo I’ve come across. I like the integrated On/Off switch at the back.

A similar light is the Exposure Revo which I know a number of riders who would use nothing else. Unlike the E3, the Revo does not have an On/Off switch so there are a variety of hacks you need to do to get around that. Also, the mounts are more limited than with the Supernova.

imageFor road use the Busch and Muller Luxos U is the ultimate light. It is bright (with high and low light settings) and has a nice beam cut off so it won’t blind oncoming drivers. What really sets it apart from ALL the competition is the the integrated USB cache battery (see below). No need to worry about anything else to charge your devices. There are two shortcomings to the light: (i) it is not very robust. I had a relatively minor crash in the 2014 Transcontinental race (fell asleep!) and cracked the lens. Was quite a hassle to get it fixed; (ii) its mounts are poor – especially in comparison to the Supernova. My web site has lots of hacks for the mounts.  As an aside, the Luxos U uses a 2.8 mm female blade terminal on the wire to the dynamo. These are hard to find (in rural New Zealand) but I got a set of 100 off ebay for AU$ 8.

imageAnother dynamo light system that I’ve tested is the Magnic contactless dynamo system. These are proximity lights and generate electricity by being close to your spinning wheel. I did a series of tests comparing them to my Supernova and found that they were markedly inferior when it comes to light output—at least for endurance racing. For commuting they would be great and I’ve put them on one of my commuting bikes.


Rear Lights

You can’t mix lights between light manufacturers so you have to go with whatever your supplier offers.

I really like the Supernova three LED rear light. Very small aimagend unobtrusive, but bright. I wired it in with an inline waterproof connector cable from ebay which allowed me to remove it easily.

The Busch and Muller Seculia light is also very bright but—just like their lights—a real pain to mount. It has a semi imagecircular plastic mount which works fine on a seat tube, but if you have a seat bag it will not fit. In theory it can mount on one of the rear stays, but my BMC has square stays so didn’t fit. In the end I got one of the fender mounts which has a bolt and epoxied it to a computer mount. It won’t be going anywhere.

If you want to go outside the box, the Magnic imagecontactless rear light works great. It generates electricity through its proximity to the rear wheel without having to be in direct contact. You’ll probably have to be creative with getting a mount for your bike.

Because I could not get a suitable mount for the Secunia, for the Transcontinental races I used a NiteRider Solas USB rechargeable light.  This was brilliant and flashed a bright light which was visible for some distance. I’d recharge it from my USB plug during the day and it never ran out of power. Highly recommended and even when I use a dynamo light I will have that as a backup. One cannot be too visible.

USB Power

Before I started using the Luxos U I had quite the journey to get USB power. I have tried (or use) a whole range of devices.

  • The Plug II. This was my first solution. imageI was attracted to the compact design which fits into your fork steerer tube. The first challenge was getting it installed (lots of filing of metal and cussing) but once it it worked great. For about two months when it died.  This is not an uncommon issue—Ed Pickup has a photo of an attempt of at a field repair during the Transcontinental Race!  It was replaced by a Plug III.
  • The Plug III. Improved design over the Plug II, this one lasted for a Tour Divide and worked well—until about 600 km into the Kiwi Brevet when it failed. This time the plastic ‘tongue’ inside the USB where the connectors are sheared off, even though I had put tape on the plug to keep water out and reduce the possibility of this happening. The offered me a discount on a replacement but there is a saying … fool me once your problem; fool me twice my problem. I’d had enough of the Plug. Just not worth the risk of failure. If you really want to go with this sort of a unit the Sinewave Reactor has not has the same volume of reports of failures.
  • Pedal Power Universal Cable. After my second image‘The Plug’ failure I got myself a PedalPower Universal Cable. A much better alternative, although not as tidy as ‘The Plug’. It is a cable which connects to the dynamo and has a small AC/DC inverter and a USB plug on the end. Worked flawlessly. The only issue is that there was no cache battery (more on this below). So I tried the …
  • Pedal Power Super i-Cable. This is a very nicely dimageesigned system which has an integrated 1000 mAh cache battery. It has a LED display which shows if power is getting in and the battery level. A tidy unit the only thing I didn’t like was that it would not power both my GPS and my phone. Note: I’m not sure if Pedal Power are still operating. Their web site has not been updated since 2013 and they haven’t been responding to e-mails or answering the phone. Peter White lists their products on his site.
  • Busch and Muller e-Werk. This is a unitimage which converts the dynamo output to a range of user definable voltages and currents. I was going to use it to try and recharge my Ay-Up battery lights, but never got around to it. Compared to other options best relegated to a specialist application. There is no cache battery and you can buy one, but a vey expensive option compared to others.
  • Busch and Muller Luxos U. This is by far the imagebest way to get USB power as it is integrated into the light with a small cache battery so that you don’t get annoying ‘loss of external power’ messages on your GPS. The USB plug has a weather proof cover and is integrated into the On/Off switch. Very tidy.
  • ZZing. This is similar to the PedalPower Super-i-Cable. It is a power imagebank with 5 x 2700 mAh batteries in it and a USB output. It connects directly to your dynamo and is a bit larger than a Garmin 810 GPS (see right). It comes with a handlebar mount and the developer claims many hours of wet riding without failures! It has much more capacity than the Super-i-Cable, at almost half the price. The developer advised that it takes about 80 km to be fully charged so much more rapid than others like the Goal Zero.  The run time for my Garmin 1000 was a whopping 19 hours before fully discharging.
  • Biologic Reecharge Powerpack. Similar to ZZing and Super-i-Cable, a power bank with a small attachment between it and the dynamo to convert the dynamo imageto the Powerpack input. It has an integrated USB output which connects directly to the dynamo. Has a rubber cover and three buttons, two of which are used to turn it on to accept a charge, and to power your USB devices. If you don’t remember to turn the USB off it will continue to discharge. The cover also works as the mount with it wrapping around the bar of your bike (see photo). In spite of its small size the battery has a good capacity—ran my Garmin 1000 for about 10 hours before fully discharging. Around the same price as the ZZing
The inline converter for the dynamo to Reecharge
Mounted on my bike under the top tube and on the front of the headset


The Luxos U is the ‘standard’ by which I compare these options for USB power because of the simplicity of having a light with integrated USB and small cache battery. It is all you need. It costs (from Peter White) $219. So you have two other options if your light does not have USB output:

  • A battery pack with USB output (four options I’ve found); or,
  • A USB converter, and some form of battery pack.

Here are how the options compare.

System Battery? Cost (US$)
BikeCharge Yes $50
Pedal Power Super i-Cable Yes $185
Reecharge Power Pack Yes $99
ZZing Yes $110
Cycle2Charge No $75
Kemo USB Charger No $40
LightCharge II No $80
Pedal Power Universal Cable No $116
Sinewave Reactor No $220
Sinewave Revolution No $120
The Plug III No $170

If I’ve missed anything please let me know and I’ll update the table!

So after all my playing here are my conclusions for USB converters:

  • The Luxos U is the tidiest way to go with integrated unit and a cache battery—cheaper than a light and another option!
  • Avoid ‘The Plug’. Just not worth the risk of failure.  Overpriced compared to other simpler and more reliable options. The Cycle2Charge is less than half the price and does the same thing in a larger model.
  • If you have a light without USB:
    • By a combination battery pack with USB output like the ZZing (see below).
    • Go for a Kemo, Lightcharge, PedalPower Universal cable, or Sinewave Revolution and then have some from of stand-alone battery they go into.

Backup/Cache Batteries

Even with the Luxos it’s good to have backup batteries in case something goes wrong.  The earlier table lists a few devices are USB converters with backup batteries built in. The advantage this has over most others is that you connect it directly to the dynamo.

I really like the ZZing from Germany has the largest capacity that I’ve found: you can imageget it with 2700 mAh batteries. It’s a nice unit and fits perfectly on your top tube inside of a $19 ‘Deuter Energy Bag’. Tip: cut the front of the bag behind the stem to feed the cables through that way you can close the top zip.  I was a bit worried about the weather tightness of the ZZing but the develop told me “I tested it for years in the rain … The electronic parts are covered with a plastic surface against moisture”. One tip he has is that  it should be disconnected after 80 km (which is the fully charged distance) if you are not using it to power a device as it prevents over charging.  The only downside to the ZZing is that it requires a special wall adapter to recharge from AC when not running a dynamo (i.e. as your backup for when the dynamo fails).

The BikeCharge is your cheapest option but only has a 500 mAh battery. Will update the blog when it arrives to test.

The Cinq5 is a dedicated battery designed to work with ‘The Plug’. It is  a very nice unit but costs about 3 x the BikeCharge (and over half the cost of the Luxos U!) . It has a 2950 mAh battery.

Of course there are lots of external USB battery power packs available with different capacities—costing only a few dollars. The biggest issue you face is finding a battery with ‘pass through’ charging. I’ve bought more batteries than I’d like to think about which didn’t work.  Some also had the annoying habit of shutting down when I was using them. Then I found the answer: solar power batteries. Solar users have similar needs to cyclists with dynamos and what works for them will work for us. Check out this Canadian firm which has a wide range of batteries.

I’ve been testing the Goal Zero Plus 10 recharger and holds lots of potential. This not only acts as a cache battery, but you can also use the AA batteries independently—for example in your torch. It is that it is a pass-through system which lets you charge/run others while it is being recharged. Only problem is that the AAA adapter is not integrated and I’ve lost the adapter (which has to be ordered separately).  Kerry (from K-Lite) advised that the batteries can come loose so I’ve put in some packing foam and a rubber band around the outside to hold everything in place.  With the Goal Zero a good tip from Kerry Staite of Klite in Australia is to use hot glue around the recharge cable socket (with the cable in!) to ensure a good and continuous contact. For something less permanent use Bosch Bluetack.

For the batteries, I use the  Eneloop batteries.  These are really powerful (current models 2500 mAh) and in one test I ran my SPOT GPS for 60 hours on one charge. Yes, I know that SPOT GPS don’t normally run off USB … this is described in my ‘hacks’ section below.



I also take a small backup USB Eneloop charger. Light as a feather and works really well – does AA and well as AAA. Unfortunately discontinued but they pop up for sale now and then.  They are also marketed as Panasonic BQ-CC14 chargers.

One of the questions is how long do these battery packs last. I have a ‘standard’ test which is to fully charge my Garmin 1000 and then run the battery pack until the pack is fully discharged. Here is how some of them have performed.  Given that the Garmin 1000 has about 10 hours of run time when fully charged, if you run the ZZing and your dynamo fails you would have some 29 h of power for your GPS.


Hours to Fully Discharge When Powering a Garmin 1000

ZZing 2700 mAh 19
Reecharge 10
Goal Zero 2000 mAh Batteries 10
Generic 5000 mAh Cell Phone power bank 39

USB Hubs/Splitters

Any USB solution has a single port and usually imageyou want at least two (or more). I’ve tried a range of them and my preference was for one of these small dual USB ‘splitters’.  What is interesting is that some of these can draw much more current than others which makes it more of a challenge to recharge your devices.  For example, I tested a range of hubs and my Garmin GPS drew in the range of 0.13 to 0.42 amps showing that some were very inefficient. For this reason it’s really useful to spend $10 and get a USB voltage and current detector when you are testing gear—they are not expensive and can identify power drains. Get one that can handle two outputs such as these so you can easily test multiple devices.

image image

I have since changed my view on these splitters … I found that one my setups was not charging reliably. I traced it back to the fact that—after many thousands of kilometres—the ‘socket’ on the USB splitter imagehad become loose. This is similar to the failure I observed with my Plug III where the ‘tongue’ sheared off. While using something like Bluetack or hot glue would likely solve the problem (tape didn’t work), I’m going to try something much more flexible and reliable: $2 splitter cables. This way I can tape each of the connections and they will not vibrate, and be fully waterproof.

USB Hacks
I’m transitioning towards using the Goal Zero with high capacity rechargeable batteries as both my cache battery and my emergency backup in case of dynamo failure.  My two ‘essential’ battery powered devices are my SPOT GPS and my Tracer 360 vest. The latter is a fibre optic vest that I wear at night. It has the most incredible illumination and is essential to anyone who rides at night.

Both of these run from 3 x AAA batteries. The SPOT is very power demanding and calls for Energizer Lithium batteries. It will work with others, but only for a short period—even high capacity rechargeables don’t last too long (i.e. less than a day with the SPOT).

So I’ve done a simple ‘hack’ of both devices wherein I run the power wires from a standard USB cable to the appropriate positive and negative terminals. Detailed step-by-step instructions for my Spot are here. This results in 60+ hours of run time for my SPOT GPS and 30+ hours for my Tracer 360 from one set of Goal Zero recharged batteries. I’m going to put in a small USB female socket to each as a permanent solution so I can then run them from my Goal Zero power pack directly, and unplug it between use. While the Tracer 360 will run from any USB power pack, only the Goal Zero has worked with the SPOT. I suspect because the SPOT must go into some low-current mode between signals and the USB power packs detect this as the device being removed.


4 responses to “Powering Your Gadgets For Endurance Races

  1. You need to test this headlight too:

    Same optics as Luxos U but more robust. In my experience a great headlight with lots of different mounting options from SON.

    Are you doing TCR16 too 🙂 ?

    • Mathias,

      Thanks for the suggestion! Looks really good. Unfortunately not racing the TCR this year – still off the bike trying to deal with my infected prostate. However, I’ve booked a flight to Frankfurt for the GST in June. Hopefully will be up to the shorter 1200 km distance by then. All the best for the TCR – watch out for the dogs!

  2. Pingback: The Great Dynamo-USB Power Run Off | Chris Bennett's Triathlon and Cycling Blog

  3. Great article(s). What I do is run my GPS (OSMAnd, includes offline navigation) and everything else on my Galaxy S5 phone, with a SON and Luxos unit. What I’ve learned to do is charge extra phone batteries directly with an external battery charger. This way I avoid the 30% or so cost of power transference from the battery to the phone. Then I just switch batteries when it’s time. If I’m lucky I might be able to charge my extra external battery too. The problem with this approach, though, is increasingly phones are not being built with removable batteries. Anyway, thought I would mention this.

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