I love that, while riding my mountain bike, I carry a hydration pack. I've loved this from the first one I owned. I carry tons of water, plenty of supplies. I often carry both a mini pump, and a shock pump, just in case.
When I started riding road bikes more heavily, I found that I also loved the freedom of NOT carrying a pack with me. It isn't the freedom of being prepared, so much as the freedom of less to carry. The freedom of only carrying the essentials. I suppose this is the same sort of freedom that ultra light-weight backpackers enjoy.
However, when on my road bike, there is always something nagging at the back of my mind: Where can I get water when my water bottles run low? On my mountain bike, I always carried too much water. I'd fill the pack all the way up--even for a short 1-hour ride. As it turns out, this is just a symptom of a much larger problem: I drink too much water when I ride.
Perhaps this sounds foolish. Perhaps you're the person who routinely bonks because of dehydration. This never happens to me. I am much more likely to be searching for a bathroom, than to be dehydrated.
On Saturday, I went on a fast-paced 43-mile ride. It was quite warm, and windy. I brought two huge water bottles. I had to refill them. That's right, a ride that took less than 2:20, I needed more than 50 oz of water. In fact, it was probably closer to 75 oz.
The other day, when I met up with that guy on the Orbea, I noticed that I had two bottles (large), while he only had one small one. I drank about 5 times more often than he did. I was wishing for a restroom before I finished.
Is it a survival instinct? I just need to have plenty of water, in case my bike explodes and I have to walk home? Do I sweat more than the average person? I do sweat a lot.
Going forward, however, I've decided to try and cut back my water consumption during rides. Here's an interesting read on the subject of drinking too much. Although I've never, to my knowledge, experienced any of the symptoms of drinking too much, I'm going to try and cut back and see how that effects my riding.