Now that it's like a locker room outside every day, I make it about 30 minutes before I'm out of water.
Here's a couple thoughts on the hydrating topic, and a few others.
As Britton pointed out, you can't just wake up the morning of a race or a hard workout, chug a couple tall glasses of water and think you're good for the day. Particularly for racing (and particularly for the perennially white-hot Tour of Kansas City coming up in about a week) you've got to be hitting the water consistently for three or four days beforehand. When I'm getting ready for a race, you won't see me without a water bottle nearby in the days leading up to the competition. I'm not slamming water. I'm taking small sips every few minutes. I usually drink about four liters of water, sometimes five or six if I'm working out hard that day.
Having said all that, though, there's a common mistake people make when they drink water — namely, being that they drink too much. You hit too much water and you'll flush out your electrolytes. If you try and race without enough electrolytes, your legs will feel like rubber, you'll be kinda drowsy and once the pace picks up in the race, you're almost sure to be left behind. One trick I learned from racing track and cross cross country races was keeping some small, simple candy in my pocket the night before and the day before the race. I'd usually have Jolly Ranchers or a few rolls of Smarties. I'd pop a Smarty ever 10 or 15 minutes ago. The simple sugar would restore electrolytes and keep my blood sugar at a normal level. Don't go apeshit with the candy, obviously. I'm not talking about eating this stuff like a kid who just landed a pillowcase's worth of booty on Halloween. But keep the sugar around.
Regarding coffee, there's so much literature out there that discusses whether it's good for athletes or bad, whether it dehydrates you or not. Most trainers and doctors I've spoken with about it say that if coffee is a diuretic (a substance that draws water from your tissue and blood) it's such a weak one that it's offset by the amount of water in your coffee that's taken in. My tip on coffee when I race is I'll try to go all week without coffee. Then on race day, I'll find a Starbucks and get a coffee with a shot of espresso about an hour before the race if I can. You get so much energy from it that I hardly can stand still in line waiting to register for the race.
An endurance athlete's diet is actually a pretty simple thing. You need to eat a lot, and you need to eat a wide variety of different foods. It's really that easy. I'm always amazed at all the snake oil that gets brandished in discussions about healthy athletic diets. I'm particularly surprised at how few people understand that athlete's need to eat a fairly good amount of fat. When I'm really thinking about my diet, I break it down my intake roughly like this:
• 60 percent carbs.
• 25 percent protein.
• 15 percent fat.
The fat part is pretty easy to figure out. Look on the nutrition label and see what percent calories from fat take up of the overall number of calories. If it's 15 to 20, you're generally OK to eat it. Of course, some things like hummus have a much higher ratio of calories from fat. It doesn't take someone with much education to know what kind of fat is good and what's bad.
I won't get into any detail about training because lots of different things work (and don't work) for a lot of different people. But one thing I see all the time in endurance sports is people who don't know when to quit. It's so easy to overtrain in endurance sports. And getting to a point where your body is burned out is a miserable thing. Beyond your body feeling horrible, you get depressed, you can't sleep well and your life temporarily sucks (or sucks more if you feel like your life always sucks in general). More often than not, you need to be taking slow to moderate rides. I see people kill it a lot on rides or runs throughout a week and then they get to race day and the complain that they feel like shit, even though they barely did much the day before. The simplest advice is to listen to your body. If you start a ride you figured would be a hard or moderate ride but you're feeling run down, why push it? Just take an easy day. Or an off day. That's why I don't keep training logs or write down elaborate training plans. It's too easy to go all neurotic when you see a day on your training calendar where you were supposed to hit some hard intervals but you were only able to softpedal for a few miles. You start thinking about what it is that fucked you up and shit just spirals down from there. Just listen to your body and do what it tells you to do. I'm not saying you shouldn't push yourself beyond your limits and comfort threshold from time to time — you won't get better if you don't learn to break through pain barriers. I'm just saying, listen to your body, use common sense and don't be an idiot.