I hate to carry anything that I have no chance or very very little chance of using. I hate even more carrying stuff in my back pockets if I can help it. Over time, i have narrowed what I carry to what I am likely to ever use:
Spare tubular pre-glued (under the seat)
small mini pump
can of Vittoria PitStop
iPhone wrapped in cash inside a ziplock bag in center pocket.
That is it. Anything else is either unnecessary or I'll call my team car (wife) for help.
BTW, I do second the idea of the extra water bottles. Sometimes I wished I did that when I go on longer rides through areas that would take me 2-3 hr before I see a place where I can refill the bottles.
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Arguing with ignorant people is an exercise in futility. They will bring you down to their level and once there they will beat you with their overwhelming experience.