Is the ride supported and/or will you be passing any place where you can buy food and water? I always have tire levers, patch kit, spare tube, inflator and CO2 cartridges in my saddle bag. I also carry cash, sunscreen, chamois cream, Kleenex in my top tube bag and wear my road ID. Food and cell usually go in my jersey pockets. How much food and water depends on whether the ride is supported and/or goes by a gas station or convenience store. Two bottles wouldn't be enoughto get me through 50 miles. Even if supported, I always keep at least some food with me. You never know when you're going to bonk, get lost or otherwise delayed.