Super Bright & Actually Works - 50-lumen Daytime Flash mode cuts through traffic and bright daylight. Real-world riders say it’s "seriously visible" - cars notice you faster, even from a distance.
Battery That Doesn’t Flake Out - Solid modes last up to 5.5 hours, flash modes up to 19.5 hours. And if you forget to recharge? Auto Safe Mode kicks in to squeeze out another 45 minutes, so you’re not left in the dark.
Lightweight, Tough, and Easy to Use - It weighs just 40 grams with the mount. Reviewers love how it mounts quickly, stays put, and survives rough, everyday riding without breaking.
USB Charging + Remote Compatible - No batteries. No hassle. Recharge it like your phone. Plus, it can hook up to a USB remote switch if you want easier control while riding.
Built to True Series Standards - we didn’t just guess at the lumen output, these lights meet and beat the advertised brightness. Reviewers back it up: you will notice a big difference versus cheaper lights.

Azzon Enterprises (comprador verificado) –
Light weight and very bright light and remembers your last setting!
I use this on the rear of my bike and it is light weight and very bright. I use it in the strobe twice setting and what is nice is when I turn it on with just one short press it remembers my last setting so that I don’t have to cycle through the settings to get to the one I use most. It charges pretty quickly and lasts more than my generally hour long bike rides.
Douglas Taylor (comprador verificado) –
Excellent light and secure mount
This is the second Thunderbolt I have bought because my Wife swiped my first one after me using it for a couple years, so I bought this one. These are almost painfully bright at night so even in a very bright city night you WILL be seen. I have mine mounted to the back of my helmet using a zip-tie along with the rubber mount and it is very secure, and the same for my wife’s. The mount is somewhat difficult to put the light in, but that is the beauty of the mount since it isn’t going to fall out unless you crash your brains out, and then you want it to. The earlier Thunderbolt was thinner and rounder in the lens but I like both the new version and the old version for different reasons. A very, very good light for cheap money.
lorenz m. worden (comprador verificado) –
Excellent Product
Serfas products “set the bar” for bicycle-related gear. The Thunderbolt performs as I would expect from this company – 100% satisfaction. I would recommend it to others.
William (comprador verificado) –
Best Light on the market
Long battery life on charging and works in blink or steady state moe
GOODO’S (comprador verificado) –
Work great…easy install
Easy to install and use.Bright red light with flashing…good charge time…solid construction
bob (comprador verificado) –
An oldie but a goodie
An oldie but a goodie!
Tony E (comprador verificado) –
Good overall life
Replaced an older one that lasted about 10 years before recharging stopped. Good overall life as well as good battery life.
rafael gutierrez (comprador verificado) –
Comentario
Batería dura poco.
Francisco Lafayette (comprador verificado) –
Isn’t waterproof but is excellent
Isn’t waterproof and I kinda just assumed it was. I rode with it in rain and it died, doesnt work, excellent light tho, ill be buying another, 4 out of 5 stars.
K. Sedota (comprador verificado) –
So good I went back and bought another.
My old thunder bolts gave up the ghost after 10-12 years so getting the new version was my first choice. It did not disappoint. Great battery life. More flash options and I love the new mount. Hopefully I’m good for another 10 years.
Jay Olsen (comprador verificado) –
Works as described
Easy to setup, easy to install, easy to operate