The functionality of these is great, however, if the bottles are empty the slightest vibration pushes the bottles out. I have lost half a dozen water bottles at this point unknowingly. Ive spent so much on replacing the water bottles I might as well have bought a much more expensive solution from the start.
I was skeptical that these cages could hold the larger (24 oz.) bottles in when hitting bumps, but haven't had a single one pop out yet (it's been at least 1,000 miles, and I cross railroad tracks regularly). Also, despite the angle, it's possible to pull the bottles out and replace them while remaining in the aero position.
I agree with the previous review about them being a small hassle to install, and not having 100% confidence that they're tight enough, but so far so good.
I needed to grind down one of my seat rails for the second holder to fit. The first holder barely fit in. Right now they're fine but I worry that they are not tight enough. You really can't get to the bolts once you tighten them and rotate them into proper position. So you need to hope that they are tight enough. But have had no problems yet.