The Serfas Thunderbolt (UTL-6) bike tail light is a small, inexpensive bike tail light that attaches with silicone stays to pretty much any part of your bike. You don’t need tools – you just snap the stays in place. I put it on my rack, and it attaches very securely. Unlike many other lights, it does not move around, so that you get to work and find you have been shining your light at the ground the whole time. And the easy mounting system means you can fix it to any part of your bike, or even your backpack. Making it ideal for those who have more than one bike.
The stays and charger have remained the same over many generations of this light, which I always like. I hate to be forced to buy a new light because I have lost one little rubber stay.
Pros of the Serfas Thunderbolt Bike Tail Light
- Like all good bike lights, the Serfas Thunderbolt (UTL-6) bike taillight could save your life one dark night (or winter morning). This alone justifies spending $40 on it. Plus, it comes in a range of seven different really fun colors!
- The Serfas Thunderbolt is extremely bright, thanks to its 30 micro-LED strip, and I am sure it makes the back of my bike visible for at least half a mile. On the other hand, it is small enough that cyclists behind you are not blinded.
- It produces 35 lumens of pure red light.
- It’s very light (50 grams).
- It has four modes: high beam steady; low beam steady; high blink and low blink. Of course, the battery lasts way longer on the blinking modes. I like the high beam steady, which unfortunately eats up the battery very fast (less than 2 hours).
- It is easy to switch off – just hold down the on button for several seconds.
- The USB cable socket is pretty standard – for example, you can use a Garmin bike computer USB cable to charge this light via your computer.
- The silicone mounting bands make it a cinch to mount this light – it just takes seconds, and no tools required!
Tips for Using your Serfas Thunderbolt Tail Light
- Note that the battery will last only about 2 hours with the light on steady beam. It lasts MUCH longer on blinking mode, and is probably more visible that way too.
- The light comes with just a USB cable to charge it. It will charge much faster direct from the socket using an Apple type plug, than if you plug it into a computer. Still, the charging time is 3.5 hours, so remember to plug it in as soon as you get home!
- To avoid losing the mounting bands, I have developed a tidy habit of putting these into the top pocket of my cycling jacket the minute I remove the light from my bike, so they are safe and handy.
Features of the Serfas Thunderbolt Tail Light
- Light silicone body
- 30 micro-LED strip
- Modes: 1.75 hours (high beam); 7 hours (low beam); 3 hours (high blink); 9.5 hours (low blink)
- Unique mounting system that allows for endless mounting possibilities
- Highly Water resistant
- Weight: 50 grams
- Comes in 7 different color options
Bottom Line on the Serfas Thunderbolt Tail Light
The Serfas Thunderbolt Tail Light offers a quick, easy and affordable way to make yourself clearly visible from behind. It is way brighter than about 90% of the bike tail lights I see on the road. And it matches up really well with the very bright Serfas TSL-350 headlight, reviewed here.
Buy this Serfas tail light if you don’t like using tools, you want to be easily seen from behind, and you don’t want to spend a huge amount of money.
In many ways, the Serfas Thunderbolt Bike Taillight is a perfect tail light for the Average Cyclist!
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