To See or Be Seen?
The first consideration when looking to purchase lights for your bike is whether you need to see where you’re going or be seen by other road users.

Lights designed to see will usually be much brighter, have a larger battery to ensure suitable run times along with a narrower beam focused to illuminate the road ahead of you. If you’re riding in areas that are poorly lit like back streets, bike paths or mountain bike trails this type of light is vital for seeing obstacles or obstructions on your ride.

Lights designed to be seen will usually have a wider beam to help being seen from more angles and be less powerful as they don’t need to illuminate the road ahead. The benefit that comes with this is typically a smaller overall size, weight and lower price while using a smaller battery for similar run times.

It is also important to consider a light for daytime riding as well as night, using a flashing light for attracting attention during the day is one of the best ways to make yourself safer.

Brightness
Lumens is the main method used for measuring brightness, the higher the number the brighter the light. However be aware Lumen can sometimes be misleading as other things such as the LED’s used, lens and beam angle also contribute to how bright a light is. Generally we would recommend starting at a minimum of 250 Lumens for a front ‘to see’ light and 600 minimum lumens for off-road use.

Battery
The vast majority of modern lights now use USB rechargeable Lithium-Ion batteries. These will save money by not having to replace batteries and are much more convenient, allow higher power output and longer run times. Some high powered lights will use an external battery pack to reduce the size and weight of the light which can be great for helmet lights but keep in mind mounting or carrying the battery.

Run Time
It’s crucial to get a light that can operate for the length of your ride to keep you safe. It’s important to look at the run time and brightness of each mode; high, medium, low, flash etc when making a comparison between two lights to ensure you’re comparing the same brightness and effective run time.

Use
Considering what type of riding you’ll be doing is another important decision when purchasing lights. On-road riding mostly involves fairly straight roads so a narrower beam angle aiming its focus directly ahead is best here. Off-road riding typically involves tighter corners and more obstacles like ruts, rocks and roots to look out for, so a wider beam is more important. Water resistance can also be an important consideration if you’re commuting year-round or riding on muddy mountain bike tracks.

Mounting
Most bike lights are secured using either rubber straps, a bracket with clip or velcro. Mounting will generally be an easy affair if your bike has a traditional round handlebar and seat post, however particular attention should be paid if your bike features an aero seat post or handlebar. For commuting or road riding, generally mounting your front light on the handlebars will be the best bet. However a helmet mount is particularly important for mountain bike tracks with tight switchback corners. This allows you to look into and through corners before you begin turning your handlebars. Easy and quick removal is an important feature to consider as you’ll often find yourself taking lights on and off for charging.

Weight
Weight can be particularly important if you’re planning on mounting your light on your helmet. Generally for helmet use we’d advise looking at a weight of less than 125 grams.