This bottle mount is still fine after at least 20 casual rides of >20 km each. By casual I mean about 25 km/h on roads and less than 20 km/h on flat but still rough bike paths. It is designed to use the bike's built in screws.

I originally designed it around the dimensions of the "Clean Bottle Original Bike Bottle", but I've used it with a Coca Cola 710mm plastic bottle once - when I forgot the other bottle!

As shown by the file names, I went through a few iterations of this thing before I stopped it from snapping if I shoved in a full water bottle or accidentally hit the mount with my feet while cycling. The only maintenance I needed to do on this thing was tighten the screws on a 35 km ride coming out of the winter. The slots in the stem are made so the screws can get quite loose before inadvertently releasing your bottle.