Good holder, my issue is in the short time I've had it I dropped my bottle quite a few times through bunny hops & rough bumps on a road bike. The angle at which mine sits doesn't allow bottle to fully seat properly. So now after hard impact I just reach back to make sure I haven't dropped my bottle. Also wearing slightly on my carbon seat post, any more damage its coming off

I immediately knew I wanted to mount my water bottle cage to the seat rails on my bike when I noticed this was even a thing online. All I had to do was a quick search and bam! Here we are. This little awesome mount. And oh man is this thing awesome. I received it and it was neatly packed and had all of the mounting hardware.

In the package, you receive the following:
* Not compatible with i-beam type saddle. Standard dual rail type only
* Lightweight at 80 grams
* Bottle cage mounting screws included
* Not compatible with I-Beam type saddle; Standard dual rail type only

First I opened it and looked around and thought to myself "aw man there's no instructions and they are in japanese". I wasn't too bummed because it is pretty easy to figure out, but I always enjoy having instructions so I know I am properly doing it. After actually looking at the packaging, there is a little graphic on the back of it telling you how to install it. This was better than anything. It helped me get this done very quickly! To make things easier, I took my saddle off of the seat post to install it. It was a little tough trying to do it with it still attached to the seat post because I did not have a bike stand for working on it. If you want to get it done quicker, I recommend doing what I just said.

All in all, the mount is very strongly made. Stays firm in place and does not move around. A lot of people were complaining that it runs parallel to the ground, but I was able to angle mine perfectly to where it's just at an angle but a good angle and will not fall out.

If you are interested in mounting your water bottle cage to your seat post, this IS the way to go. You won't find a better deal out there and for the price of this one, you get a very quality piece of equipment.

I love this add-on to my bike for long (half and full Ironman events), in addition to my two frame cages. Very easy to put on. You simply remove the metal plate, slide it on top of your saddle supports and then mount the bracket with two screws. I use this with two Ibera cages that I bought on Amazon as well and these hold two 20oz Camelbak (also from Amazon of course) bottles for additional hydration. You can lower or raise the bracket to some degree but the bottles will not interfere with your seating position. I never even know they are back there until I need to reach behind me for a bottle. I don't recall the weight but it's marginal unless you're someone who feels that 10g can improve your triathlon performance considerably.

Held up great through Ironman Texas' 112 mile bike with a wedge bag in front of it and two spare tubes taped to the back of each arm. The angle of the arms was fine for me, and did not cause the bottles to hit my back (being more upright probably also prevented it from launching any bottles on the bumps, but it appears you can force them to a slightly different angle if needed). I was able to reach the bottles in the back easily to refill my primary bottle between the aero bars and to squirt ice water on myself. According to aero studies, this setup behind the seat should not affect aero as much as a bottle in the usual boss. I cannot speak for flying dismounts, although you would really have to practice (and have long legs) with rear bottles there.

Mounting was a simple self-explanatory procedure that required only a 3mm hex key. Despite this, it comes with a manual with instructions in both English and Japanese... Just in case. The aspect of the threaded mounting plate seemed a bit dodgy, but I'm sure it'll hold up; the mounting hardware is long enough to the extent to which the screws come out of the mounting plate just enough to be able to accommodate some nuts for some extra reinforcement. (Which is what I would be doing if I were one of the many buyers that overtorqued and broke the threads in the mounting plate)

I use the mount in tandem with an ordinary bottle cage and a Camelbak Podium chill; the top of the bottle is easy to grab and my hands are just where I need them on the neck... Squeeze, drink, done. If you're unfamiliar with this style of mounting, you'll get used to it after a while. I don't exactly have to worry about the bottle coming in contact with my butt, but it likely depends on the bottle size and what saddle you run. I have a State Bicycle/generic Vader saddle, and it all fits quite fine. Even if fitment is an issue, I'm sure it would be possible to use different hardware and some spacers/washers to produce a gap... Or you could just bend it, but that's a little too bubba.

All in all... It's a mount, alright. It sure does do the thing. Looks slick too. Might end up purchasing the double mount so I can be even more aero...