From the winding roads of rural villages to the bustling city streets, bike dynamos have long served as a beacon of light for cyclists worldwide. 

These remarkable devices, powered by the very motion of pedaling, offer a self-sustaining and eco-friendly solution for illuminating the way ahead. 

In this article, we’ll see everything about bike dynamos, uncovering their inner workings, benefits, and practical applications. 

Prepare to discover how these unassuming mechanisms harness energy to generate a reliable source of power, revolutionizing night-time cycling and opening up new possibilities for adventure and exploration on two wheels.

What is a Bicycle Dynamo & How it Works

A bicycle dynamo is a device that generates electrical power while the bicycle is in motion. It typically consists of a small generator that is mounted on the bicycle and connected to the wheel. 

When the bicycle is ridden, the rotational motion of the wheel causes the generator to spin, converting mechanical energy into electrical energy.

Inside the dynamo, there are usually magnets and coils of wire. As the wheel rotates, the magnets rotate along with it, creating a changing magnetic field. This changing magnetic field induces an electric current in the wire coils through a process called electromagnetic induction.

The generated electrical current is then typically used to power lights on the bicycle, such as the front and rear lights. The current may be directed to the lights directly or stored in a rechargeable battery for later use.

How Much Electricity a Bicycle Dynamo Can Generate

A bicycle dynamo typically produces an electrical output of six volts, resulting from the energy generated by pedaling. Hub dynamos can sometimes be adjusted to produce 12 volts. The generation of electricity starts immediately when pedaling begins and stops when pedaling ceases.

Historically, dynamos have been primarily used for powering lights that run on AC power. However, with advancements in battery technology, LED light technology, and charging technology, along with the availability of USB cables, it has become possible to convert the AC current generated by dynamos into DC current, which is required to power electronic devices. 

Pros and Cons of Dynamo Hubs

The worthiness of installing a dynamo hub depends on factors such as your riding style, duration of rides, and power requirements. In the following section, I will present the advantages and disadvantages of utilizing a dynamo hub.

Dynamo Hub Pros

Constant Power Supply

Dynamo hubs provide a continuous source of power as long as the bicycle is in motion. This means you don’t have to worry about battery life or recharging devices such as lights. It ensures reliable lighting and other powered accessories throughout your ride.

Sustainable and Eco-Friendly

Dynamo hubs are environment-friendly because they generate electricity through mechanical motion, eliminating the need for disposable batteries or external power sources. They allow you to reduce waste and lower your carbon footprint.

Improved Safety

With a dynamo hub powering your lights, you no longer have to rely on batteries that may run out of charge at inconvenient times. Dynamo-powered lights are always ready, providing better visibility and safety, particularly during low-light conditions or night rides.

Versatility

Dynamo hubs can power not only lights but also other devices like USB chargers, GPS units, or even smartphones. This versatility allows you to use various electronic accessories without worrying about battery life.

Low Maintenance

Dynamo hubs are generally reliable and require minimal maintenance. Once installed properly, they usually run smoothly without the need for frequent adjustments or replacements.

Function Reliably in All Conditions

Irrespective of muddy or dirty wheels or adverse weather conditions, dynamo hubs consistently generate power when you ride.

Dynamo Hub Cons

Initial Cost

Dynamo hubs can be more expensive upfront compared to standard non-dynamo hubs. The cost includes the hub itself, wiring, and compatible devices. However, the long-term savings on batteries and convenience might offset the initial investment.

Added Weight

Dynamo hubs are heavier than traditional hubs due to the inclusion of the dynamo mechanism. This additional weight can slightly affect the overall performance of the bicycle, especially during acceleration or climbing.

Increased Rolling Resistance

Dynamo hubs produce a small amount of resistance when generating electricity. While this resistance is minimal and often unnoticeable during regular riding, it can have a slight impact on the overall efficiency of the bicycle.

Compatibility and Installation

Dynamo hubs require compatible devices, such as lights and chargers, to ensure proper functionality. Additionally, the installation might require some technical knowledge or assistance, especially if you are not familiar with bicycle maintenance and electrical wiring.

Limited Power Output

Dynamo hubs have a limited power output, usually ranging from 1.5 to 3 watts. While this is sufficient for most bicycle lights and small electronic devices, it may not be suitable for high-power devices or devices that require quick charging.

Steep Hill Challenges

When charging power-hungry devices, the hub’s additional resistance might impede climbing steep hills. It may be necessary to adjust to slightly lower gears for uphill climbs while utilizing a dynamo hub for charging. 

Another issue is that if you’re ascending a hill at a slow speed, your device won’t charge effectively, requiring you to disconnect it until you reach the hilltop. This can become frustrating when traversing hilly terrain, as your device will repeatedly start and stop charging. However, this inconvenience can be mitigated by employing a buffer battery.

A Guide to Dynamo Hub Performance

Dynamo hubs exhibit variations in their performance, with some surpassing others in terms of power output, efficiency, and drag reduction. 

Dynamo Hub Efficiency

A dynamo hub serves as a mechanism to convert your pedaling power into electricity, enabling the powering of lights and electronic devices. However, not all the energy you input into the hub is efficiently converted into electricity, as some energy is lost due to friction within the hub and magnetic resistance.

For instance, the Schmidt SON28, one of the most efficient hubs, produces approximately 3 watts of power but creates 5.5 watts of drag at 20 kph while utilizing a USB charger for device charging. This implies that around 55% of the drag produced by the hub is utilized for charging the device, while the remaining 45% is lost. 

In comparison, a comparable yet less efficient hub, the Shimano UR700, generates about 4 watts of power at 20 kph but causes around 10.5 watts of drag. Consequently, only about 38% of the drag contributes to charging the device.

The specific efficiency of a dynamo hub can vary significantly and is influenced by multiple factors such as speed, the type of light being used, the devices being charged, rider weight, bike weight, wheel diameter, terrain, and more. 

Dynamo hubs typically exhibit efficiency levels ranging from 20% to 60%. Most hubs operate at maximum efficiency when cycling at speeds around 20-25 kph (12.4-15.5 mph).

Dynamo Hub Power Output

Reliable dynamo hubs have power ratings of either 1.5, 2.4, or 3 watts, measured at a speed of 20 kph. The power output of the hub varies as your speed changes, with higher speeds resulting in greater power delivery. The power delivered also depends on the power requirements of your lights and the devices being charged.

Typically, most dynamo hubs can charge a phone through a reliable USB charger at speeds ranging from 12-18 kph (7.5-11.2 mph). Phones generally begin charging at around 2.5 watts. Dynamo-powered lights often reach their maximum brightness when traveling at approximately 20 kph (12.4 mph), although they will still provide illumination at lower speeds.

It’s worth noting that some dynamo hubs can produce more power than others, even with the same wattage rating. 

For example, a lower-end dynamo hub might only produce 1 watt at 15 kph (9.3 mph), which is insufficient for charging a device or generating significant light. Conversely, a high-end hub with the same 3-watt rating might produce 3 watts of power at just 15 kph (9.3 mph).

Among the currently available options, the Shimano UR700 stands out as one of the most powerful dynamo hubs on the market. At a speed of 25 kph, it can deliver a peak output of approximately 5.5 watts to a USB charger. In comparison, the SON28 hub only provides around 4.5 watts at the same speed.

Dynamo Hub Drag

Dynamo hubs introduce resistance that results in a decrease in speed. You can feel this resistance when you manually rotate the axle of a dynamo hub with your fingers—it doesn’t spin freely and feels somewhat uneven.

The uneven sensation arises from the interaction of the small magnets passing by the stationary large magnet as the hub rotates. For instance, the SON28 hub contains 26 magnets inside, and each time a magnet approaches the pole of the stationary magnet within the hub, you will experience these slight irregularities. 

When the magnetic poles come close, they repel each other, creating resistance. As the magnets move past the poles, they continue to repel and push apart. These forces almost balance each other out, but the resistant force remains slightly stronger.

When you’re not using the dynamo hub to charge a USB device or power a light, the resistance is minimal, and you won’t notice the unevenness. Most dynamo hubs generate 1-5 watts of resistance without any load, depending on your speed and the quality of the hub. For instance, the popular SON28 hub produces less than 2 watts of drag at 30 kph (18.6 mph).

When you connect a USB device to charge it or activate your light, the resistance in the hub increases. The amount of drag experienced largely depends on the power requirements of the light or device you are using and the hub’s design. It’s important to remember that different hubs have varying levels of efficiency, and some create more drag than others.

For instance, to generate sufficient power for charging a phone, a hub might introduce a drag of 4.5-12 watts, depending on your speed and the hub’s efficiency. To operate a bright headlight at its maximum brightness, the hub might cause a drag of 18-24 watts, again depending on your speed and the hub’s efficiency.

Assuming you produce 100 watts of power through pedaling, an efficient hub may consume only around 5% of your pedaling power to charge a USB device. This level of resistance is typically imperceptible. 

However, an inefficient hub could consume up to 10-20% of your pedaling power to operate a power-hungry light at its brightest setting, significantly impeding your speed. In such cases, you will clearly feel resistance while riding.

It’s important to note that even regular hubs create some drag. A well-maintained, high-quality hub typically introduces about 0.25-0.5 watts of drag, depending on your speed, with drag increasing at higher speeds. 

By subtracting this value from the drag created by a dynamo hub, you can determine the additional drag caused by installing a dynamo hub on your bike.

A Detailed Explanation of Parts of a Dynamo Hub System

When purchasing a dynamo hub, typically, you acquire the hub itself without additional components necessary for its operation. To utilize the dynamo hub, you will need to obtain several other parts. 

These components comprise the complete dynamo hub system and include the hub itself, a dynamo light, a USB charger, electrical connectors for the light and bike charger, and, optionally, a buffer battery.

If your intention is to install a dynamo hub on your current bicycle, it is likely that you will need to purchase each part individually. In the following section, I will provide an overview of each component comprising a dynamo hub system and provide guidance on what factors to consider when selecting them.

Dynamo Hub

The dynamo hub is the central unit that contains the generator. Notable brands in this category include Shimano, Schmidt SON, Sturmey Archer, Shutter Precision, and KT. To utilize the dynamo hub, you will need to assemble a wheel around it. This entails purchasing a rim and spokes and either building the wheel yourself or having it professionally assembled.

USB Charger

USB chargers serve the purpose of regulating the power output from the dynamo hub to prevent excessive voltage that could potentially damage your devices. Additionally, they convert the AC power generated by the dynamo hub into DC power, which is compatible with electronic devices for charging purposes. 

It’s important to note that some energy is lost during this conversion process. The most efficient chargers employ both software and hardware optimization techniques to maximize efficiency. USB chargers also feature a USB outlet where you can connect your device for charging. These chargers are typically mounted on the frame, steerer tube, or handlebars of the bicycle.

Bike Dynamo Lights

Dynamo lights are available in various brightness levels and beam patterns, measured in lumens and lux respectively. When selecting a light, it is important to consider your specific usage requirements. 

Some dynamo lights are optimized for off-road riding with a symmetrical beam pattern, while others are designed for road riding, aligning their beam shape with the contours of the road. Certain dynamo lights offer adjustable brightness settings, beam shapes, and even battery assist modes. 

Mounting positions for most dynamo lights are typically at the height of the front wheel’s top, either on the fork crown or handlebars. Most models are designed to be waterproof, and some dynamo lights even incorporate a built-in USB charger. There is a wide range of options available from popular brands such as Busch+Mueller, Schmidt, Supernova, and Herrman.

Electrical Connectors

To ensure compatibility, you may need to purchase connectors that match the connectors on your dynamo hub for your light and USB charger. Two common connector types are available, one manufactured by Shimano and the other by Schmidt SON. 

These connectors attach to the wires of the USB charger and dynamo light and then plug into the corresponding connector on the dynamo hub. It is important to note that these connectors are not interchangeable, and they must be disconnected when removing the front wheel.

Buffer Battery

The buffer battery is an optional component that allows you to continue charging or powering your devices when your riding speed is too slow for the dynamo to provide sufficient power or when you are at a complete stop. Using a buffer battery prevents your device from experiencing continuous power interruptions as the dynamo output fluctuates. 

While a buffer battery can be beneficial, it is not essential. However, it is worth noting that approximately 20% of the energy is lost when charging from a battery. Therefore, the most desirable buffer batteries are those with pass-through functionality. 

These batteries can deliver power directly from the dynamo to your device when the dynamo supplies adequate power while also charging any excess power. This ensures energy efficiency and minimizes wastage. 

Pass-through batteries tend to be more expensive compared to regular batteries, which can only either charge or power your device, but not both simultaneously. Some dynamo USB chargers are equipped with a built-in buffer battery. 

For optimal compatibility with the dynamo, it is recommended to use batteries with a capacity of 5000 mAh or less, as they have lower resistance and can be easily charged by the dynamo.

How to Choose a Dynamo Hub

When deciding on a dynamo hub for your bicycle, several factors should be taken into account. These include the devices you intend to power, the type of axle and brakes on your bike, the spoke count, and the nature of your riding activities.

In the following sections, I will elaborate on each of these aspects to assist you in selecting the most suitable dynamo hub.

Dynamo Hub Power Output

Dynamo hubs come in three power output options: 1.5 watts, 2.4 watts, and 3 watts, typically operating at 6 volts and 0.5 amps. Among these, the 3-watt dynamo hubs are the most commonly found. 

The power output is generally measured at a speed of 25 kph or 15 mph. When a hub is advertised as 3 watts, it means that it can produce a minimum output of 3 watts of power at 25 kph.

As the speed increases, the hub generates more power, while at lower speeds, the output decreases. For instance, when descending a steep hill at 50 kph, the hub might reach a peak output of 10 watts or even higher. Conversely, when climbing a steep hill at a slow speed of 10 kph, the hub might produce less than 1 watt of power.

If your typical riding speed is below 25 kph (around 15 mph) and you intend to charge devices via USB, a 3-watt dynamo hub is recommended. These hubs usually generate sufficient power to charge a phone starting from speeds as low as 12-20 kph (7.5-12.5 mph). Many bicycle tourists and bikepackers opt for 3-watt hubs as they often travel at lower speeds.

For bikes with smaller wheels, such as folding bikes with 16-20″ wheels, a 2.4-watt dynamo hub may be more suitable. The higher RPM of smaller diameter wheels helps maintain speed, resulting in increased power generation. Moreover, a 3-watt hub may create excessive resistance on a bike with small wheels.

If your typical riding speed exceeds 15 mph (around 25 kph) and your intention is solely to power your lights, a 1.5-watt dynamo hub could suffice. However, if you plan to power electronic devices as well, you may prefer a 2.4 or 3-watt hub.

Dynamo Hub Electrical Connectors

Dynamo hubs are equipped with spade connectors that facilitate the connection to lights and USB chargers. Currently, there are two competing designs in the market: one developed by Shimano and the other by Schmidt SON.

Both connector designs perform similarly as they effectively transfer power from the hub to the light or USB charger. Due to the existence of these two competing designs, most dynamo lights and USB chargers are sold without any connectors attached to the wire ends. 

This allows you the flexibility to select the appropriate connector type for your specific hub. You will need to install the chosen connector onto the wires of your light and USB charger, which may require the use of a wire cutter.

There is also a third connector design from Schmidt known as Schmidt SL. In this configuration, the side of the dynamo hub establishes an electrical connection with a plate mounted on the fork dropout. The plate is soldered to the wiring integrated into the fork.

The advantage of this design is that it eliminates the need to disconnect any wires when removing the front wheel. The hub automatically connects upon contact with the plate in the dropout. 

However, the drawback is that this setup necessitates a custom fork specifically designed to work with the Schmidt SL system. It is likely that you would need to install a new fork to accommodate this system. 

Axle Type, Axle Diameter, and Hub Width

When selecting a dynamo hub, it is important to consider factors such as axle type, axle diameter, and hub width, as not all dynamo hubs are compatible with every bike frame. The hub must be specifically designed to match your axle type and hub spacing. 

Fortunately, dynamo hubs come in various sizes to accommodate a wide range of bicycles. Here are a few common dynamo hub sizes:

• 9mm x 100mm quick release: This size is commonly found on older and lower-end bikes.
• 12mm x 100mm thru-axle: Suitable for road bikes.
• 15mm x 100mm thru-axle: Designed for mountain bikes.
• 15mm x 150mm thru-axles: Intended for fat bikes.
• 9mm x 135mm quick release: Specifically for quick-release fat bikes.
• 15mm x 110mm thru-axles: Meant for mountain bikes with boost spacing.

In the provided list, the first number signifies the axle diameter, while the second number represents the axle length. The required hub width will depend on the front hub spacing of your particular bike.

Number of Spokes

Dynamo hubs are manufactured with various options for spoke hole counts, including 20, 28, 32, 36, and 48. Lighter road bikes and folding bikes commonly employ 20 or 24-spoke front wheels. 

On the other hand, most mountain bikes and touring bikes utilize 32 or 36-spoke front wheels. Tandems and expedition touring bikes typically feature 48-spoke wheels. It is essential to match the spoke count of the hub with that of the rim.

The number of spokes directly influences the strength and weight of the wheel. A higher number of spokes results in a stronger wheel, but it also adds weight. Maintaining balanced spoke tension across the entire wheel is crucial to ensure its stability and strength.

Brake Type

Dynamo hubs cater to both disc brake and rim brake bikes. Dynamo hubs designed for disc brake bikes come with rotor mounts, typically using a 6-bolt configuration. On the other hand, hubs for rim brake bikes do not have rotor mounts.

A Look at Dynamo Hub Alternatives in the Market

Dynamo hubs may not be the ideal choice for every cyclist due to various reasons. Some riders may prefer to avoid the additional cost and complexity associated with installing a dynamo hub, while others may be concerned about the added weight and drag it introduces to their bike. 

Fortunately, there are alternative options available for generating electricity while riding. Here are a few alternatives:

Solar Panel and Charger

Advancements in solar panel technology have significantly improved their efficiency in recent years. Nowadays, it is possible to keep small devices charged using solar power. Compact 28-watt solar panels, such as the BigBlue 3, can be mounted on top of a rack and panniers. 

One advantage of using solar panels is that they don’t cause drag like a dynamo hub. However, it’s important to consider the extra weight of the solar panel. Additionally, solar panels may create wind resistance. 

The main drawback is their reliance on direct sunlight to generate power. This makes solar systems slightly less reliable, as they may not produce enough power on cloudy days or while riding in shaded areas. It’s also important to keep the panel clean for optimal performance.

Battery Pack

A portable battery pack offers the convenience of charging your phone, GPS, light, camera, and other devices without causing any additional resistance. With a 10,000 mAh battery pack, you can typically charge your phone 2-4 times, depending on its battery size. However, there are a couple of drawbacks to consider. 

Firstly, you still need to charge the battery pack itself. Every few days, you’ll need to find a suitable location where you can sit down for a couple of hours while your battery pack recharges. Additionally, large battery packs can be quite heavy. This setup works well for day rides or short tours where substantial power requirements aren’t necessary.

Stopping to Charge at Power Outlets

Alternatively, you can rely on finding power outlets to charge your devices. Power outlets can often be found at campsites, restaurants, coffee shops, and sometimes larger supermarkets or department stores. 

The drawback, however, is the need to continuously search for places to charge. When you do find a power outlet, you’ll have to halt your journey for an hour or two to charge all your devices. In rural areas, it may take days before you come across a power outlet, requiring you to pass through a city or town to recharge.

Another Option for Charging: Rim Dynamos (Bottle Dynamos)

Rim dynamos utilize the same technology as dynamo hubs to generate power. However, there is a notable distinction: the dynamo unit of a rim dynamo is mounted on a fork arm instead of being integrated into a hub. This type of dynamo is a compact cylinder that rests against the rim. As the wheel rotates, it causes the rim dynamo to spin and generate power.

Rim dynamos were commonly found on vintage bikes before dynamo hubs became prevalent. In the past, these dynamos would rub against the tire rather than the rim. They were primarily used to power small headlights. However, early models of rim dynamos were often noisy and affected the bike’s handling characteristics.

Over the years, rim dynamo technology has significantly improved. Modern models offer several advantages over dynamo hubs and may be worth considering for certain riders.

Rim Dynamo Pros

Reduced Drag

Rim dynamos can be moved away from the rim when not in use, minimizing additional drag and allowing for a smoother ride.

Easy Installation and Repair

Unlike dynamo hubs, rim dynamos can be clamped onto the fork without the need to rebuild the wheel. This makes installation and repair processes simpler.

Lightweight

Rim dynamos generally weigh less than hub dynamos, contributing to overall weight savings on the bicycle.

Higher Power Output

Rim dynamos have the potential to produce more power compared to hub dynamos, offering greater charging capabilities for devices.

Removability

Rim dynamos can be easily removed when not needed, providing flexibility in terms of usage.

Rim Dynamo Cons

Reduced Power Output in Wet Conditions and High Speeds

When rims are wet or when riding at high speeds, the rim dynamo may experience slippage against the rim, resulting in decreased power output.

Increased Resistance

Rim dynamos tend to create more resistance compared to hub dynamos, potentially affecting the bike’s performance.

Noise

Rim dynamos can be louder than hub dynamos, producing an audible whirring sound that may be perceived as annoying.

Limited Compatibility

There are fewer options available for lights and USB chargers that are specifically designed for rim dynamos, potentially limiting device compatibility.

Finicky Positioning

Proper positioning of the rim dynamo against the rim at the correct angle and pressure is crucial, which can sometimes be challenging and require adjustments.

Maintenance Requirements

Rim dynamos require periodic maintenance, including the replacement of o-rings to ensure optimal performance.

Limited Functionality in Muddy or Debris-Laden Conditions

Rim dynamos may not perform well when the rim is contaminated with mud, snow, or other debris, leading to decreased efficiency.

What is a Dynamo Light

While the term “dynamo” usually refers to the component that generates power, it is also commonly used to describe a light that is powered by a dynamo hub.

Dynamo Headlights

Dynamo headlights, specifically, rely on the power produced by a dynamo to function.

In addition to a small battery or capacitor that keeps the light illuminated briefly after coming to a stop (known as a stand light), a dynamo headlight requires the wheels to be in motion in order to provide illumination. It is important to note that dynamo lights cannot be powered by a battery.

Conversely, most battery-powered headlights cannot be directly powered by a dynamo. However, there are some lights, such as the Light & Motion Rando 500, that allow for slow charging of the internal battery via a dynamo while riding.

Modern dynamo headlights, which are based on LED technology, are quite intricate. They need to convert the alternating current (AC) power generated by the dynamo into direct current (DC) through a circuit known as a rectifier. These lights often include over-voltage protection and logic circuits that detect when the stand light needs to be activated.

In the past, older incandescent dynamo lights could be connected directly to a dynamo hub since they could function with either AC or DC current, making them simpler. However, these lights are not as bright or reliable as LED lights.

One significant difference between dynamo headlights and the majority of battery-powered bike lights is that most dynamo headlights comply with the StVZO standard. StVZO is a German standard that specifies the design requirements for lights to ensure compliance. The main distinction of compliant lights is the use of a specially-shaped cut-off beam that directs the light onto the road or trail without causing glare for drivers.

This feature is particularly beneficial for road riders as it focuses the light where it is needed without dazzling other road users. However, the StVZO-compliant lights do not provide the wide beam shape that is more advantageous for off-road riding.

Dynamo lights are most popular in Europe, and many prominent manufacturers such as SON, B&M, and Supernova are based in Germany, which explains why most of their lights adhere to the StVZO legislation. 

Exceptions do exist, of course. Lights like the KLite BikePacker Ultra V2, Exposure Revo, and Sinewave Beacon use standard round beams, which are typically preferred for off-road riding. These options are highly popular among bikepackers.

Dynamo Rear Lights

Dynamo rear lights are commonly attached to cables that run along the bike’s length and connect to the back of a dynamo headlight.

The simpler rear lights consist of an LED housed in a suitable casing, with a long cable soldered onto them. These lights depend on the stand light circuit in the headlight to remain illuminated when you come to a stop.

On the other hand, more advanced rear lights are designed to function independently from the headlight and are directly wired into the hub. These lights typically have their own stand light circuit.

In modern rear lights, a coaxial or twin-core cable is usually used to establish a connection with the headlight. However, older lights sometimes utilize the bike’s frame as the ground for the circuit.

How Much Drag a Dynamo Light System Can Add

While all dynamo systems introduce some level of resistance, it is generally negligible for most riders at typical speeds. In 2014, Fahrrad Zukunft conducted lab testing that showed even the least efficient dynamos added approximately 3 watts of resistance when the light was switched off at normal riding speeds of 20km/h.

When the light is switched on, the resistance increases to around 6 watts at the same speed. At higher speeds of 30km/h, the least efficient dynamos may introduce approximately 8 watts of resistance.

To explain it simply, when the light is on, the electricity produced by the generator, which powers the lights, generates its own magnetic field. As this current passes through the stator, it works against the magnets in the rotor, resulting in increased resistance or drag.

The amount of drag will increase as more power is drawn. Opting for a lower-wattage headlight, such as a 1.5-watt instead of a 3-watt, would yield less resistance, but it would also mean less light output.

On the other hand, the most efficient dynamo hub tested (the SONDelux) only added around 6.5 watts of resistance at 30km/h when the light was switched on. To provide some perspective, this difference in resistance is roughly equivalent to the impact of riding with a dirty chain versus a clean chain, according to Jason Smith of Friction Facts.

Apart from resistance, some riders may notice subtle sensations associated with certain dynamo setups during rides. For example, a radially-laced Shutter Precision dynamo hub can create a distinct rumbling feeling through the handlebars at higher speeds. 

Similarly, the Velogical dynamo may transmit a faint buzzing sensation throughout the bike, noticeable to those who pay close attention.

On the contrary, the SONDelux wheel is generally free from noticeable buzzing, except when descending at speeds of around 45km/h or higher, where a slight rumble can be felt through the handlebars.

Whether these sensations become an issue depends on individual sensitivity, but in my experience, they can be easily ignored or tuned out.

Best Dynamo Hubs Recommendations For You

1. Schmidt SONDelux

The SONDelux dynamo hub has proven to be the top performer in my tests. Its exceptional smoothness makes it virtually undetectable during regular riding, except at extremely high speeds, while still providing reliable power even at lower riding speeds.

However, this level of quality does come with a significant price tag. The SONDelux is one of the most expensive dynamo hubs available, priced at £199.99/$296.

If maximizing power output is your priority, the SON 28 may be a more suitable choice, as it is specifically optimized to deliver the highest output possible at slower riding speeds. 

In case you are fully committed to a dynamo lighting setup, I wholeheartedly recommend any of SON’s hubs without hesitation.

2. Shutter Precision SV-9

If you’re working with a limited budget and unable to afford a SON hub, Shutter Precision (often abbreviated as SP) offers a viable alternative. While SP hubs may not provide the same level of smoothness as SON hubs, they are considerably more affordable, with prices starting at around £110 RRP.

During my testing, I had a mixed experience with SP hubs. The first SP SV-9 hub I tested developed significant play shortly after starting the testing period. Once repaired, I encountered the opposite issue, with the hub seizing after some time.

In both instances, ISON promptly repaired the hubs, and customers should expect similar service. However, my second hub, which was brand new, has been trouble-free for over a year of riding, and there are no indications of that changing any time soon.

Ultimately, while SP hubs may not match the smoothness of SON hubs, they offer a more affordable option, and with proper care and maintenance, they can provide reliable performance for extended periods.

3. Shimano Dynamo Hubs

If you’re on a tight budget, weight is not a major concern for you, and you prefer the option to perform some maintenance yourself, I recommend considering one of Shimano’s dynamo hub options.

Although Shimano’s dynamo hub range has become smaller in recent years, they still offer affordable options for both disc and rim brake setups. These range from entry-level non-series components to the higher-end Deore XT hub.

While it’s not possible to fully disassemble these hubs, you can service the non-drive side bearings and replace the entire generator and drive side bearing assembly without needing to remove the hub from the wheel. This allows for convenient maintenance without the hassle of unlacing the hub.

Choosing a Shimano dynamo hub provides a cost-effective solution without compromising on functionality, and the ability to perform certain maintenance tasks yourself adds to the overall appeal.

4. Velogical Sport Bottle Dynamo

If you find yourself owning multiple bikes with a combination of rim and disc brakes, and you prefer not to invest in separate dynamo wheels for each, Velogical’s dynamo could be an excellent choice. Additionally, it provides the flexibility to completely disengage the dynamo when desired.

The initial setup of the Velogical dynamo may require a bit of attention, but the design and construction of these compact units are truly remarkable.

Best Dynamo-Powered Light Recommendations For You

1. SON Edelux II

Once again, I highly recommend SON as my top pick. The craftsmanship of SON’s Edelux headlights is unparalleled, and their meticulously designed beam optics, licensed from Busch + Müller, are ideal for both road and gravel riding.

The Edelux light offers versatility with the option of vertical or upside-down mounting configurations. Furthermore, its standard 10mm mount allows for convenient installation in various positions on your bike, such as the handlebar, fork crown, or front racks. As an added bonus, it even comes in a range of vibrant colors. 

2. Busch + Müller IQ-X

The Busch + Müller IQ-X employs comparable optics to the SON Edelux but presents them in a more cost-effective and slightly less rugged casing.

The housing combines alloy and plastic components, which, although not as sturdy as the Edelux, have no impact on the light’s performance during regular use. However, the difference in build quality becomes noticeable when initially setting up the light.

One aspect I didn’t particularly appreciate was the leftover cable remnants when I used the headlight without a rear light. Nonetheless, I easily resolved this issue by securing them with a small zip-tie and adding some shrink wrap for a neat solution.

3. Exposure Revo

The Exposure Revo is a meticulously crafted dynamo light designed specifically for off-road expeditions. Its exceptional stand light feature is particularly noteworthy, offering up to an hour of usable light that gradually decreases from 400 lumens as it discharges. This makes it highly suitable for bikepacking adventures.

The Revo’s coaxial connectors are incredibly user-friendly, and its output port serves the dual purpose of charging devices or powering a rear light. Additionally, the light is compatible with a wide range of Exposure’s other accessories, although it would be desirable if the brand offered a fork crown mount as well.

To Wrap Up — Bike Dynamo

With advancements in technology, modern dynamos are becoming more compact, lightweight, and durable, making them a practical and eco-friendly choice for cyclists of all kinds. 

So, embrace the power of motion and harness the energy of your ride with a bike dynamo, and illuminate your way to a greener future.

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Bike Dynamo — Frequently Asked Questions

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