“I CAN POWER MY GARMIN, CHARGE MY PHONE, CHARGE MY CAMERA AND RUN MY LIGHTS 24/7, ALL WITHOUT HAVING TO STOP...”
Dynamo Lights…The culprit in one of the most common questions I get when it comes to my set-up on multi day trips. How do I power my devices while on the run? I can power my garmin, charge my phone, charge my camera and run my lights 24/7, all without having to stop.
The answer relates to my ‘golf ball’ sized hub, otherwise known as a ‘Dynamo.’ Dynamo hubs are clever pieces of equipment and incredibly simple devices to use. For some reason, Dynamos are a source of confusion with those new to adventure cycling.
Could the confusion stem from the name and the fact that people relate this with the magician ‘Dynamo’ and fancy magic tricks? Possibly, but I think the main reason is that dynamos just aren’t widely used within the community and as such, bike shops aren’t required to know a whole lot about them. In addition to this, it makes more sense for a bike shop to sell a customer an ‘off the shelf light’ and make a quick sale, then it does for them to try and sell a custom wheel. It could also be the fact that ‘charge and go’ style lights now have a relatively impressive battery life and most would argue that a dynamo isn’t necessary.
Outlined below, I’ve attempted to cover everything you need to know about Dynamo’s. I’ve also provided my own tips and recommendation with respect to setup and equipment choices based on my own ‘real world’ experience.
Essentially a dynamo hub, is a hub that is built into the front wheel of your bike, that generates electricity, enabling you to power your electronic devices. The original dynamo hub’s were bottle shaped, attached to the fork and driven by the circulation of your tyre. As the wheel rotated, the dynamo would rub against the tyre and generate friction which could then be utilised as electrical power. These original dynamo’s were inefficient and caused early wear of the tyre. In addition to this, they zapped watt’s from the rider, slipped against the tyre in wet conditions, created an audible humming noise and had to be carefully positioned in order to engage with the tyre at the right angle.
Fast forward to the present, and Dynamo hub’s are now almost as small as a standard hub. They come in a range of colours, spoke configurations and axle standards in order to meet the demands of the most discerning cyclist.
A common misconception that a lot of riders have, is that dynamo hub’s create an unwanted amount of resistance. Truth be told, modern day dynamo’s cost approximately 2-3 watts from your pedal stroke and as such, the disadvantage is minimal. So much so, that most ultra-riders won’t turn their lighting off during the day, as the benefit to safety far outweighs the penalty imposed as a result of the dynamo ‘drag.’ I’m guessing that the energy bar that’s stuffed away in your rear pocket and the sunglasses that are perched in the vents of your helmet are costing you more energy as a result of aerodynamic drag!
My Dynamo hub of choice and the hub that I’ve been using for close to two years now, without fault, is the Shutter Precision unit from sp-dynamo.com. Not only are these units reliable, they come in a range of different spoke/hub standard configurations and importantly, retail at a fraction of the price of other Hub systems such as the ‘SON’ unit from Germany.
In addition to the hub itself, what else do you need?
I’m currently using a light/usb charging apparatus that I purchased through Kerry at klite.com.au. The K-lite equipment is all handmade in Australia and represents incredible quality and value for money. The reason I purchase all of my equipment through K-lite, is that it’s all compatible and amazingly simple to setup.
My current setup includes the following:
- Bikepacker Pro 1300 lumen Standlite - The light itself also includes a capacitor which acts as a small battery pack. The capacitor is a ‘must have’ in my opinion and is helpful for when you stop and light is required, traffic lights for instance.
- Simple Bar Switch - Think of this as the wire that runs from the hub itself up towards your cockpit. There are two connections on the ‘non-hub’ side that allow you to connect your ‘Bikepacker Pro Standlite’ and your ‘USB Charger.’
- Sinewave Revolution USB Charger - The USB charger connects into the second port of the Bar Switch and converts the energy generated from the dynamo, into a format that allows you to charge from a USB plug. Garmin, phone etc.
Another piece of information that’s worth adding, is that the Dynamo hub will not generate enough electricity for you to run your light and charge a device at the same time. Generating light and charging your devices is a bit of a juggling act and with time, you will develop a regime whereby you will charge equipment during the day, and then run your light during the night.
I personally don’t run my rear light through the Dynamo apparatus, however there are systems available that do have these capabilities. My rear light of choice is the Exposure Blaze, which provides 80 lumens of flashing light, for 48 hours at a time. I generally run my rear light 24/7. This is mainly for visibility whilst out on the road. Once a day I will remove the light and charge it via the USB plug to ensure that I’ve got enough juice to see me safely through the night.
Note: I am in no way endorsed by klite.com.au or sp-dynamo.com and so the above facts and figures represent factual information and knowledge that I have picked up over the years.
The important thing when looking at building a dynamo wheel relates to the construction of the wheel itself and ensuring that other factors such as spoke count and rim choice are well considered. I recently caught up with Adrian Emilsen from Melody Wheels in Perth, a Dynamo Wheel specialist, who provided the following insight with respect to wheel construction with a particular emphasis on dynamo hub’s:
"Building a dynamo wheel is no different to any other wheel in terms of how it’s built. The main difference is that dynamo wheels tend to be used in conditions where absolute performance is less of a concern than reliability. The key components of the dynamo wheel are as follows:
Shutter Precision (SP) and Schmidts Original Nabendynamo (SON) are two of the leading brands that we’ve used to build many dynamo wheels. There are subtle differences between SP and SON hubs in terms of the hub geometries and hubshell design, however both provide a solid platform for an excellent dynamo wheel. The expected bearing life of a hub is an important consideration although extremely context specific. SON, who use SKF bearings, have a 5 year warranty on their hubs with an expected on-the-road life of at least 50’000km. SP offer a 2 year warranty on their hubs and will replace hub bearings at no charge if there are any bearing wear issues within this time. It’s worth noting that neither SON nor SP dynamo hubs can be serviced by your local bike shop. Both hubs are required to be sent back to the factory (in Taiwan (SP) + Germany(SON)) for bearing replacement. So far we’ve had no reports of bearing failure from either manufacturer.
Its possible to reuse the rim on your existing front wheel and build a dynamo hub into it. However, if you are considering a whole new wheel you’d be best to speak with an experienced wheel builder to discuss what rim option will best suit your needs. In addition to a broad range of rim design and quality considerations, one of the most important considerations is rim weight. This is because rim weight is a strong proxy for the strength of a wheel and its ability to withstand a number of dynamic loads. Generally speaking we would not recommend a rim of less that 440g for a reliable dynamo wheel (in the 700c/29er rim size).
Most dynamo hubs are designed with a higher-spoke count of 28 or more spokes.
The choice of spokes is again contextual, but we only use stainless steel spokes from leading spoke manufacturers (Sapim + DT Swiss). Double butted spokes have improved weight savings and fatigue life over straight gauge spokes. To keep the weight down, we find that the 1.65mm double butted Sapim D-Light is our most popular spoke for many dynamo wheels. In cases where the wheel is heavily loaded, the triple butted (2.2/1.8/2.0mm) Sapim Force is our preferred spoke. Ultra-light bladed spokes (Sapim CX Ray or DT Swiss Aerolite) are also an option, however they can be more susceptible to damage if something impacts them directly. They are also less suited to roadside wheel repairs (requiring additional tools) to stop the spokes from twisting. For these reasons we recommend mostly round double butted and tripled butted spokes for dynamo wheels.
We build most dynamo wheels with brass nipples because ultimate weight savings are not such a priority. Brass is a non-reactive alloy of Copper and Zinc that has a high resistance to corrosion for long-term durability and serviceability. Aluminium nipples are one-third the weight of brass nipples, however they can be affected by galvanic corrosion when they come into contact with other metals, electrically conductive materials such as carbon fibre rims, and more corrosive environments. Despite many negative opinions, we still recommend Alu nipples in a range of wheel builds. Quality aluminium nipples are forged from 7075 ‘aircraft grade’ aluminium for improved strength and hardness. The process of anodising the nipples (when done well) provides a good electrical insulator against galvanic corrosion."
I trust that the above information has provided you with a clearer insight into how a dynamo hub works and the ancillary equipment that is needed in order to convert your wheel generated energy, into a source that can provide light and power.
When it comes to purchasing dynamo hub’s there are a number of things to consider:
- What will you use it for?
- What brand will you buy?
- What environment will you use it?
- What ancillary equipment will you need and will this equipment ‘plug and play’ directly with the hub that you’ve chosen?
- Do I require both the front and rear light to be dynamo powered?
What makes purchasing a dynamo setup difficult is the range of equipment that is available and the compatibility unknowns between differing brands. I recommend contacting a sole supplier/distributor directly and talking with them about your specific requirements. Kerry from k-lite is a fantastic resource when it comes to the ‘ancillary equipment’ and his knowledge of all things ‘dynamo’ is incredibly vast. For all ancillary equipment, contact Kerry. With respect to the Wheel Build and the incorporation of the dynamo itself, Adrian from Melody Wheels is an expert in this field and should be your first port of call.
Note: K-lite does not sell hub’s directly (for this you will need to visit sp-dynamo.com or another hub supplier), however when purchasing from the K-lite website, you are given the option of selecting which hub you will be using and this in turn enables Kerry to send you the specific equipment which in turn, allows you to ‘plug and play.’