It's important to drink water along the gels and bars, it will help absorb them into your system, and some products act like a sponge and will dry up your system. Timing? On long rides, I try to consume at least 300 calories an hour between my drink mix, gels and food. This usually means every hour drinking about 1 bottle of drink mix, one squirt of gel from the flask and a little bit of dried fruit for a couple of Fig Newtons. I go for the bars when it I think it's a good time to. I'll also stop at a convienence store once or twice and grab a banana and sometimes Pop Tarts. If I remember right, your body can only digest ~300 calories per hour (of course everyone is different), there's not much point in taking in a lot more than you can digest. More often than not, I see people suffering from under eating and hydrating rather than over doing it though. A couple of quick other things I thought of. Use chamois buttr and bring some extra to apply around the halfway point, you'll thank yourself for it. I bring my drugstore baggie with me, it has Advil, Tums, and E-Caps (electrolyte tablets that just contain sodium and potassium). On long rides 100-200 miles I take an Advil and E-Cap at each rest stop, sometimes more if I'm sore or have been sweating a lot. All of those items will help with cramping issues.