Serfas Thunderbolt USB Taillight

I have two of these, and I usually run one on the seatpost of a road bike, or two high on the seat frame of my recumbent trike. Blinding brightness, and good battery life. If you need more life, run the light on a lower setting. It's still very visible in daylight.The mounting system with the thick rubber straps works well and mounting takes 5 seconds. I broke a strap, and ordered two more from Serfas; inexpensive and they arrived quickly. Great customer service.$36 isn't cheap, but this very functional, water resistant light is worth it over a $15 crappy light. Highly recommended.

First off, I commute A LOT at night and I am very choosy about the lights I use on my bike. I've been using this a few months shot of a year and can confidently say it is the best and only taillight I'll use. This thing is bright! I mean the kind of bright that would annoy motorists who are too close, which is a good thing! It does a great job at getting someones' attention which is the purpose of using a taillight. It attaches relatively easily to most points on a bike including but not limited to the seat-post, the rear triangle, a milk crate, etc.. The battery will generally go a week or two without really needing charging if I use the pulse modes, but it is easily charged with the USB cable it comes with. And in case anyone is wondering I have used this when it is raining and have dashed trough puddles with it in the line of fire and it is still kicking, so wet weather use is definitely OK. IMPORTANT: 40 Bucks may seem like a bit much for a taillight, but this thing is worth every penny, it is just an excellent choice for those who have to ride at night or in inclement weather. Ask yourself, is saving a couple bucks really worth a trip to the emergency room?

As a guy who has biked 6,000 miles per year for the last 6 years, I have found some lights lacking, but this is not one of them. In fact, it is the best group ride tail light that I have used. I got my first one with a used bike that I purchased. It never failed until I accidentally let it get submerged in rain water. ...So I bought another on soon after that.Why is this so good for group rides? ...Well, because when you are with a pack, all of those retina burner lights with the white flash in the center can make fellow riders aggravated. / We even had a person have an accident due to being somewhat blinded by an intense blinking tail light and then going into a very dark trail.This Serfas light has 4 light modes plus off. The light can be seen for a mile and can be bright, but it is not so hard to look if you are riding behind it, because the light is all red and is distributed along a panel, with no mega-white center, etc.The battery lasts very long and seems to be able to go all day, even when you use the constant-on mode.This is my group-ride go-to light, and I am very picky about this sort of equipment.

My wife and I are commuting cyclists and have started using Surfas rechargeable lights almost exclusively. The UTL-6 is extremely bright, brighter than any other 20-30 dollar battery powered taillight I've used in the past. I think it is worth the extra cost.Reasons I like it.1. Brightness.2. Since I ride multiple bicycles, I like that it doesn't need a mount to attach to the bike. Clipping those hard plastic tabs to your belt loop isn't always ideal, and generally results in the plastic breaking. I've found the rubber on the Surfas lights to be strong enough to be taken on and off again over and over and over without feeling like I'm stressing the product.3. Surfas has used the same cable for charging over several generations of the USL/UTL series. I have Surfas lights spanning 4 years of product line, and they all us the same USB Mini adapter, which is a standard cable, easily found in most houses with technology at this point.Things I don't especially like.1. It's a bit bulky, but I can't complain because of the brightness. It still can fit in your pocket without too much trouble.2. USB Mini is good, but USB Micro would be a good switch in future generations, as Most (non iPhone) phones use this size now. I long for the day when I only need one type of cable for charging everything!3. If you don't have much seat post exposed on your bike, you might need to get creative with where you attach the light, but probably not too much of an issue most of the time.

This is a great, versatile and bright light. It is rugged and reliable.There are a few flaws that prevent me from giving it 5 stars.1) the battery life just isn't that great. I have a Cateye Volt 300 headlight and it lasts MUCH longer between charges. I'd expect a tail light to be able to keep up.2) the low battery indicator is very hard to discern when using the light in blinking mode; the red tail light bleeds through to the orange battery status LED.3) it has a "Mini USB" port for charging, rather than a Micro USB port. Nothing uses Mini USB anymore. If your phone isn't an iPhone, it has a MicroUSB charging port. If you find yourself away from home and in need of a charge, you are much more likely to find a Micro USB cable than a Mini USB cable.I'm keeping this light, but if it gets lost or broken, I'll probably replace it with a Cateye Volt 50.Revision: This is entirely a subjective adjustment, but after going through several charge cycles, the battery life has improved considerably.