Serfas Thunderbolt USB Headlight

I've had the rear light for awhile and happily got the front light too. These are insanely bright and in low blinky mode really catch the eye. I'm an urban cyclist this light is more about being seen than illumination. Road signs reflect the light really well, but I don't feel it would illuminate the road as well as a more spotlight-like headlamp.The main reason I got this was because my other front light (by Topeak) turned itself on too easily and I'd find it had been blinking in my jacket pocket all day with barely any charge left. This light has a switch that requires deliberate action and you can throw it into your panier or pocket without worrying that it will turn on accidentally. If you wear thick gloves it may be tough to turn on, but I've never had a problem.The silicone mounting straps give you the flexibility to attach it to different parts of your bike, and I was able to put a rear Thunderbolt on the back of my helmet easily. Serfas sells replacement straps - if you need them, get the longer ones because you'll have more options for mounting. I've used them on my handlebars, seat post, rack, seat stays, and helmet. I'm an urban commuter so the fact that it's quick to attach and remove is a plus, I keep in in my backpack or panier when I'm not riding because thieves here suck.It's survived riding in the rain with no troubles at all. I keep one charge cable in my panier for office use and one at home.

Previous to this light, I was using a Cat-Eye 200 lumen light on my handlebars to improve visibility, but it was really only effective for cars mainly in front of me. This new light provides much more side visibility for cars that might be about to enter into an intersection from a roadway I'm about to pass by. This light is very bright, but it would not be good for riding at night for purposes of illuminating the roadway. As others have mentioned, this light is to be seen, as opposed to being able to see. It fits okay on my Cervelo R3, but the top tube is a little shorter so that the straps from this light are forced to be applied at an angle (pinched in) instead of being evenly spaced. The light only lasts about 2 hours on the high beam flashing mode, so I tend to use it on the low power flash setting to get more use between recharges.**** NOTE **** This light MUST be removed from your bicycle to be recharged. It would have been nice to simply be able to charge it on my bike like all my other lights and devices.

When I unpacked the Thunderbolt I thought it would be a dud. I thought it would throw a broad, dim beam and be of little use. After easily mounting it to my handlebar using the very clever mounting straps, I soon found that my initial assessment was way wrong. Yes, the beam is broad, but it is way bright. My 20 mile commute to work covers lightly travelled rural roads and busy in-town streets. This light make me feel much more comfortable than my old one. My entire commute was before sunrise and I *know* oncoming cars clearly saw me. While I do use two lights, one to see with and one to be seen with. This is the 'to be seen' light.I love the mounting straps. They mount the light securely with no rattles or other noise while you're riding. Nothing to interfere with the peace of a pre-dawn ride.The one nit I have to pick is that the upper surface of the light itself, not the housing, but the light bar sort of shines up into your eyes as you ride. I fixed it with a short piece of black electrical tape. Now it's perfect.

For daytime riding, it's all about being seen: #1 worry - avoiding cars making left hand turns in front of me. Most lights focus their energy in a narrow beam, useful for seeing at night; but during the day, if off axis, those night time useful lights are NOT visible.I use two white Serfas Thunderbolts on the front fork, one high, one low, and two red in back, also high and low, and run them in the high power, flash mode. The beam pattern on these Serfas lights is about 160 degrees, so canting them slightly, I get 360 coverage. They weigh 50 grams - so 4 are less than 1/2 pound. They last for more than 2 hours, and because I charge them after each ride, they are always at peak light. When using alkaline batteries, I know I was reluctant to throw away partially used batteries, resulting in ever dimmer lights. These are bright, and even in direct sunlight, readily visible for at least 100'.Lots of motorists shout 'nice lights' to me. I know when I'm driving, I frequently don't see bicyclists, and appreciate it when they wear light clothes and use bright lights.

I was so impressed with this light, I bought two in white and two in red. The Thunderbolt casts a wide, short throw beam, not quite 180 degrees but close to it. The white Thunderbolt serves as a great fog lamp, and that's exactly why I mount it up front on either my front rack or my stem extension. Other bike lights blind me in misty conditions. The red Thunderbolt serves as one of my flashing beacon lamps. I mount it to my my rear rack or stay. The Thunderbolt has two steady modes and two flashing modes. In bright steady mode, the charge lasts more than two hours. In flashing mode, the charge has lasted quite a long time, like for weeks. But like all rechargeable lights, when battery power runs low, the light suddenly cuts out and shuts off. So I also carry a backup light for each Thunderbolt, which runs on disposable batteries. The Thunderbolt is easy to mount and remove so swapping lights is no issue. The Thunderbolt has been both useful and reliable. I recommend it for use within its limitations.