When it comes to safety on a bicycle most of us already know that a helmet is a requirement and so is a properly maintained bicycle.  During the darker hours and fall season it’s time to break out the front headlights and rear tail lights to increase visibility.  Many lights are categorized or judged based on 2 categories, and they are TO SEE or TO BE SEEN.  The Sigma brake light falls under the “to be seen” category.  Read our review for more.


Sigma has recently introduced their new cable actuated bicycle brake light that works just like a brake light would in your car.  You hit the brakes and the lights come on, you release the brakes and the light goes off.  We purchased 5 lights from Greenville Custom Bicycles and installed them to a few of our bicycles.  The cost is very reasonable at $10 and the battery should last a very long time considering the use of a small LED bulb (more on that below).  If you have questions about the light make sure you talk with your local bike shop and they’ll be able to answer any question you maybe have.

Installation is very simple, there is a single 2.5mm hex screw that clamps on the rear brake cable.  You need a 1 inch or 25mm of cable exposed to attach the light.  Installation takes just minutes.  You need to ensure that the top portion of the light contacts the cable stop firmly before tightening down.  We did have to compress the light slightly when installing to ensure that when we prepressed the brakes the light came on easily and instantly.  If too much play is left between the cable stop and the small 2.5mm anchor screw the light may not come on.

Will it fit your bike?

Sigma claims that the brake light fits u-brakes, v-brakes, canti’s, road calipers, mechanical disk brakes…but it won’t fit hydraulics.  We did have some trouble installing the Sigma brake light to both bikes that have Shimano 105 11 speed brakes installed.  The clearance wasn’t enough to install the brake.  In order to install it on our 11 speed Shimano brake we would have needed to compress the light a bit too much between the cable stop and anchor bolt, so much so that the light would have turned on without pressing the brake lever.  We’re not sure if this installation issue is true for every Shimano 11 speed brakeset but it was true for both our attempts.  Our wheels were not considered wide and the opening of the brake was very average for a 19mm wide rim with a 23c tire.  In the end make sure you check with your local bike shop about their return policy in the event the light won’t fit your rig.  In the image below you can see we didn’t have enough cable exposed on our 11 speed 105 rear brake to install the light.  A bit of a disappointment.

Weight & Appearance

If you’re wondering about weight, the light comes in at 8g on my scale, Sigma claims 7g so it’s well within the range.  Once installed it’s very well hidden and blends in with most brakes.  The only time people will notice the light is there is when the light is activated.

Brightness and Longetivity

The light is very bright considering its size but it’s by no means a replacement for a much brighter rear tail light.  The Sigma brake light is meant to BE SEEN by those relatively close to you.  Sigma claims the light will last for about 100,000 braking processes or about 200 hours of continues on use.  We’re going to trust Sigma on this claim and not going to question the battery life.

Color Options

The light comes in a wide variety of colors except hi-viz orange or green which we would have loved to have purchased but they do cover the most popular bike frame colors.  We purchased the black and white/translucent versions for our bikes.

Final Thoughts

This light is not intended to be a replacement for the much brighter rear light flashers that are meant draw attention to you while riding.  We feel this light is a very good additional safety feature for those riding in early morning, urban or dusk conditions.  The Sigma brake light is bright, light and inconspicuous.  $10 is a small price to pay for adding the ability to show you’re slowing down while commuting in the city or in a group ride.  What’s not to like about a low cost addition to safety while riding?  A great prodcut in our opinon.