On Monday, July 24, 2017 at 8:43:31 PM UTC-7, Joy Beeson wrote:
On Mon, 24 Jul 2017 12:17:23 -0700 (PDT), Doug Landau
wrote:

does anyone use seatpost mounted water bottle cages and why not?

A seat-post mounted cage keeps my spare bottle out of the panniers.
But I'm taking three bottles on tomorrow's ride. But the third needs
to be kept on ice anyway.

Aaak! Four bottles! (stops typing and fills an eight-ounce
purified-water bottle with milk.)

One of the bike bottles is in the freezer with a couple of ounces of
switchel in it. One is in the fridge, full of tea. The one in the
down-tube cage will be filled with tap water in the morning.

I've been using Red Bull and it actually works well. And it gets into your system pretty rapidly.