I've owned this light for about a year and mainly use it in the rainy PNW for commutes but have used it for night riding on densely wooded singeltrack. The light even on the lowest setting is plenty bright for dimlyunlit streets and the advertised durations for each setting were accurate. When the red low battery button starts on low setting you have about 30 min before your light dies and putting it on blink mode seems to use about the same amount of battery so don't rely on that to extend life. The mount is my only complaint. You have to really make sure it clicks in otherwise it will catapult off the front of your bike. That being said having done that once at 30mph I can say this light is really durable! Also, even when clicked in properly the mount can rattle. I fixed this by adding an elastic hair band around the mounting point to cushion the rattle. Also, the mount is very secure on trail rides IF you have a suspension fork but I've found it can slip on the bars if you are running a rigid setup. If I were to do more trail riding with this light I'd get the helmet mount.
First of all I have owned this for about a year. I do like the brightness, modes, and usb charging. I dont like the removal and strap. As already mentioned the strap is very long (good to fit lots of seatpostsseattubes?) but there is not a nice way to control the tail. it just sticks out. not a killer but annoying. The removal from the strapclamp is vertical slotted so you need lots of clearance above the light so if you have a tool bag and a med to short post you cant easily take it on and off without undoing the strap. I would recommend only for some bikes.
I've use a LOT of different tail lights over the years and this is by far the best. Of course, LED and battery technology have improved a lot of the past few years, so you'd expect a current light to be a lot better. This light is super bright, and I really like the daytime flash mode which puts out an impressive 100 lumens. One of my riding buddies has one of these as well and it's quite visible hundreds of yards up the road.
The light mounts fairly easily to just about any seat post (including aero posts) or seat stay using a heavy rubber strap.
There are two things that I'd like to see improved, but overall it works well. First, I'd like to have another daylight flash mode that reduces the flash rate to improve battery life. The daylight mode lasts about five hours, but sometimes my rides last longer than this. And second, I'd like to have a spacer that can fit between the light and my seat stay (where I like to mount it) to angle the light to be a bit more level.
A helmet mounted light set like this is awesome for both seeing where you are going (the light moves with your gaze, so you can illuminate turns and look at things that go bump in the night) and being seen. An effective addition to bike-mounted lights (and a good substitute in a pinch) as your helmet lights are easier to see by others. Nice 360-degree visibility with yellow side lights. Not too heavy, and beautifully made in the USA.