Just in time for shorter trail days, we’ve put together a mountain bike light primer for those who are looking to buy their first light. Mountain biking at night adds a new dimension to familiar trails, and it’s a great way to extend your riding season; use this guide to find the best lights for you!
Trail speed and terrain considerations.
Before you choose a light for mountain biking, it’s important to consider the types of trails you’ll be riding at night and the speeds you expect to carry. For example, if the trails you’ll be riding are technical, you’ll want a brighter light with better fill than if you’ll be riding wide dirt paths. And if you want to go fast, you’ll need a light with more range (i.e. power) than if you expect to slow things down in the dark. Also keep in mind how often you’ll be night riding; if it’s only once or twice a month in the winter you may not want to sink a ton of money into a light system.
Where will you mount your light?
There are basically two choices here: bar mount and helmet mount.
A helmet-mounted light tracks wherever you’re looking: around a switchback–at a rough patch of trail, etc.–which many riders prefer. The trade-off is that helmet mounted lights can feel heavy on the head, which some riders have a hard time getting used to. Remember, with a helmet-mounted light you’ll need to strap the battery pack to the helmet itself or stash the battery in a jersey pocket, which can harsh your flow on the trail. Lights are typically mounted to a vented helmet using velcro or stretchy straps. Helmet-mounted lights will shine down on the trail more, which is good at eliminating shadows but shortens the distance the light will carry forward.
Bar mounted light arrangements may vary, and some are better than others at dealing with tapered bars and varied bar diameters (look for ones with rubber straps or a clamp with plenty of screw length). Batteries are often mounted separately, and most riders choose to place them under the stem or in the frame triangle below the top tube. A light at bar height will shine farther down the trail, but will tend to produce more shadows in uneven terrain.
Many small- to medium-sized light kits include hardware for both helmet and bar mounting, so you can see which one works best for you. Of course, the best of both worlds is to ride with both a helmet and bar light but for beginning night riders, a medium-power helmet lamp is a good start.
Light Emitters: LED or Nuthin’
These days it’s hard to find major bike light manufacturers offering anything other than LED lamps, and it’s no surprise: LED lights are reliable and super-efficient. Stay away from lower-priced halogen and HiD-based systems: these lights suck battery life and produce a ton of excess heat. Avoid these if you find them on eBay or Craigslist.
To compare brightness between light systems, check the number of lumens (companies often claim competitors’ lumen counts are flawed, but it’s still a good starting point). At a minimum you’ll want about 400 lumens to ride trails at night; it’s enough to see the trail but you’ll need to ride pretty slowly. 🙂 For most riding situations, including technical trails and reasonably-fast descending, 750-1,000 lumens is usually adequate. Of course, you can buy lights that are as bright as 6,000 lumens!
Beyond lumen counts, the actual beam pattern is important to consider. The simplest pattern is a round one (since LED bulbs are round), but much of that light is wasted on the edges of the trail. Some lights offer a round beam pattern with a center “hot spot” and a diffused outer halo that’s good at illuminating your peripheral vision while highlighting what’s ahead. A well thought out beam pattern on a bar mounted light system all but makes up for the fact that your light doesn’t follow your eyes like with a helmet-mounted system.
Most lights ship with multiple light modes (high, medium, low, strobe, etc.) and some even offer customizable light modes, but in our experience there’s no need for more than one or two modes. High mode works best for most rides unless you need more run time (more on that in the next section) while a strobe mode is mostly good for commuting and dusk rides where you’re more concerned about being seen than actually seeing the trail.
The heart of any light system is the battery, so it’s important to pay attention to quality and reliability. Most mid- to upper-level light systems include a rechargeable Li-ion battery, while less expensive systems may ship with NiMh batteries. Charge times can vary widely (from as little as 2.5 hours to 10+ hours), so be sure to check–there’s nothing worse than forgetting to charge your light the day before a big ride. Be sure to follow the manufacturer’s charging instructions to maximize the life of your battery.
Longer battery life comes with a trade-off: the batteries are heavier and more expensive. Look for run times on high that are at least long enough for your typical ride (we look for 2 hours minimum). To compare systems, it can be helpful to calculate a simple ratio of max lumens to run time on high. For example, if a 300 lumen light gets 4 hours of run time (240 minutes), that’s 0.8 lumens per minute (this number doesn’t mean anything–it’s just for comparison). If another light’s ratio is 1 lumen per minute, that means the second light is more efficent (holding other things like battery size/weight constant).
Because batteries will degrade over time and technology is changing rapidly, we don’t recommend purchasing used bike lights unless you’re able to test and verify actual run time yourself.
It’s always a good idea to bring along a blinking red tail light on any night ride, even if you don’t expect to encounter any cars. Choose a bright, inexpensive light that can be easily strapped onto a hydration pack or attached to your seatpost.
Looking for information on specific lights? Be sure to check out our detailed Mountain Bike Light Buyer’s Guide!