I used to sport a Camelback hydration back but eventually Discovered it was more of a burden than a help. I’m 6’4” and already top heavy, so 3-4L of water on my back didn’t help that.

The pack/bladder effectively acted as a turtle shell that trapped heat on me. The water would typically get warm toward the end. My back would be sweating down my @ss crack!

Filling them was a PITA. As was keeping them clean. Bottles seem easy by comparison and I can sling them low on the bike frame. I like hydration mixes, which don’t do well in the bladders, gets slimy. Bottles are easy to clean.

I’ve seen some bikepackers mount bladders to the frame inside a frame bag or front bag. This idea intrigues me some for that type of riding.