What makes a great bike light?
Core Principles of Design
When developing our bike lights, we engineer each light from the ground up since we have years of experience from the automotive and LED lighting industry.
While each of our bike lights has it’s own specific purpose such as helmet mounting, trail riding, or road riding, we still follow a few basic design principles that we feel set our lights apart from others on the market. Let’s take a look at the design targets that we aim for on each light:
- Holistic approach to a bicycle focused light
- Beam Patterns and light requirements
- Runtime and battery strategies
- Thermodynamic performance
- Mounting Systems
- Simple user interfaces
Please note. This is a LONG and detailed discussion, but we feel it's important to understand why we did things the way we did.
Holistic Approach to Design
There are obviously thousands of different bike lights on the market, but very few are designed from the start to be specifically for bike riding.
Many are built as flashlights, and then given something to mount onto a handlebar, and calling it a great bike light. While flashlights are great for walking in the woods or poking around the house, most don’t work well for the rigors of biking.
Most lights also only seem to focus on absolute lumen values, which as we’ll see, doesn’t really tell us much about how good a bike light will be. We’ll admit right up front, we won’t be the lightest, the brightest, or even the longest lasting light on the market. We don’t care to try and be the “best” in any specific category, because doing that compromises other criteria that is important for a high performing bike light.
For example, to have the brightest lumen level, you need a huge battery pack, a huge heat sink, and going to end up with a very short battery life, or a light that overheats so quickly that you only get a few minutes at that “boost” level. So you end up with a light that sounds impressive, but is massively heavy and can only perform at that high output for a few minutes. Not so great when you have a two hour ride planned…
So, when we develop our high-performance bike lights we are looking to balance the ideal beam pattern for the specific application, how many lumens we need to hit those lighting targets, how much runtime we want to have, and then how much battery will be required to hit that reasonable runtime target. From there it’s a design approach of maximizing the thermodynamic efficiency to not only run cool, but stay compact and be easy to use. What it results in is a light that is designed specifically for your needs as a biker, and our customer reviews show how important and game-changing that actually is.
Beam Pattern and Lighting Requirements
Each type of light mounting requires a slightly different approach to how we’ll balance the light output and the beam pattern. A handlebar focused trail light such as Trail Evo needs a very wide and balanced beam pattern since the handlebars are moving left and right on twisty single track, but also have enough spill light near the front tires to help during tricky maneuvers or tight switchbacks. Contrasting that, a helmet light such as Hangover can have a tighter and stronger beam pattern since your head is pointed where you want to look, so we can tighten the beam width and boost the strength to let you see further down the trail where you are looking.
We use complex software called Lucidshape, that is primarily used for automotive lighting design. We set the design targets for candela and angles based on measurements in the field, then develop custom optics to meet those requirements. It is an extremely iterative process that can take weeks to complete and thousands of hours behind an extremely powerful computer. This is our secret sauce though. The optics may look simple, but they are a result of lots of work and in the end one of the most important parts of our lights. Since this is what your eyes are actually seeing, we want it to be the best.
Runtime & Battery Strategy
Once we have our beam pattern defined, we know our target lumens required, and then can figure out how much battery we need to meet those targets. We know that bike riders need solid consistent output since we are going on longer rides so we develop our runtimes to user friendly instead of trying to hit the “industry standard” FL1 rating . You’ll see this standard written on a lot of lights, but here is a quick explainer as to why we don’t like it:
Advertised Lumens = The average lumen value during the first three minutes of the light being turned on. No mention of light output after this 3 minute grace period.
Runtime = The time to go from 100% output to 10%. Period. No definition of the rate or curve that a light should follow.
What this means is that a light can have a “FL1 certified” lumen value of 2500 lumens, and a runtime of 40 minutes. Which one would assume is 40 minutes of 2500 lumen output, but in reality the high 2500 lumen output is available for 4-5 minutes to meet the FL1 standard, and then it throttles back hard to some arbitrary value that’s about 50-60% the original stated output, and then lasts until the battery dies.
We feel this is very misleading, and not accurate in the slightest. So when we report our runtimes we are reporting a very real, solid output. We also give all our runtimes in a graph format so that it is easier to see what is expected out of the light rather than a reported number. This also means that when spec shopping, or trying to compare the reported lumen and runtime specs from other lights to what we report, we’ll always seemingly fall short.
Though, we don’t care. We would rather have an honestly reported number because no one wants to be caught out by surprise in the middle of the woods with no light, or falling short of expectations on brightness.
Thermodynamics & Heat
The other real major challenge with developing bike lights is balancing mass with thermal performance. We all know that lights get hot. If lights get too hot then the LED efficiency drops quickly, as well as the safety issue of touching such a hot lamp, as it can result in burns. For our higher power bike lights we spread the heat load by using multiple lower lumen chips along with hours of thermodynamic simulations to optimize the housings to disperse heat as quickly as possible.
We also use innovative materials such as thermally conductive plastics and magnesium since the entire thermodynamic problem isn’t isolated to one material having a high thermal conductivity. Air speed, surface area, convection, etc are all parts of the equation. So we try and increase surface area through fins, and improve the air speed via pass-through vents on lights such as Trail Evo. It results in a very thermally efficient light that improves runtime and overall performance.
Bike Light Mounting Systems
A great bike light for a bike is useless if we can’t have it securely mounted! We’ve all experienced that frustrating issue of a light falling down or vibrating hard when riding chunky trails, or hitting potholes on the street.
Our first light, the Trail and Road Edition relied on a heavy duty silicone strap. When we developed Trail Evo we knew we wanted an extremely robust mounting solution that was easy to mount and would be repeatable.
The standard quick release mount that we engineered borrows design cues from high end DSLR camera mounts. Where a rotary cam is pushed onto a standardized "foot" on our lights to create a strong locking mechanism that can adapt over time as parts wear out. Thick glass reinforced nylon mounting points and serrated teeth for the angle adjust help keep the mount stable as a rock during the harsh forces that a light will experience.
We continually iterate and improve the mounting experience because we know it’s an often overlooked part of bike light design, and if we are going to have a great bike light, we need a great mount.
For example, we've recently introduced a thumbscrew to make angle adjustments on the trail no longer need a tool.
Simple User Interface
Lastly, we need to develop the light to be simple and easy to use. We know our bike lights are often used in the short days of winter, so thick riding gloves are worn. So when we engineer the buttons, we want just a large single press button that is easy to press, and easy to locate even in the dark with gloves on.
We only have 4 modes, high-medium-low, and an “Adaptive” mode which slowly throttles brightness over a 30-45 minute period as your eyes adapt to the darkness, resulting in a light that “feels” brighter for a longer period of time, that falls between the medium and high total runtimes. Flashing modes are included and can be accessed from the power off state. Always bewildered us that some lights have flashing modes in between the high-medium-low cycles. Nothing more frustrating than being in the middle of the woods with a strobing light!
All our modes also include a 20 minute “Get home mode” where the light output is significantly reduced and the end of battery life to give you a chance to get out of the woods. Even when the battery is going to die, we pulse the light for 15 seconds to make it very clear that the battery is going to die, and you need to slow down or stop what you are doing to prepare for it. We absolutely don’t want you to be bombing down a downhill only to have the light suddenly turn off. So we try to do all we can to make you aware that the lamp is about to turn off.