We triathletes tend to over complicate things. I agree with you Fleck as two bottles is normally more than enough. If I am doing a ride where I know I might be without water for a longer period of time then I just have the two on the frame, one between the aerobars and a saddle bag for my flat kit. Mini pump, phone and ID in middle pocket and food in the outer pockets.

In the old days it was just two bottle on the frame, saddle bag, ID, frame pump and some food.