I'll second what TT said about IGH. I can tell you from experience they're not great for the kind of riding you enjoy. I have an old steel road bike that I've ridden as a fixed gear, a single speed, and now with a Sturmey-Archer 3-speed hub. With the 3-speed, it's a nice, low performance ride. Great for commutes, casual cruising around the neighborhood, and even longer rides at moderate pace. For various reasons, it's not good at higher intensities.

I enjoy the same style of riding as you--10 to 20 miles (sometimes more) at an aggressive pace, preferably on a simple, durable machine. I would recommend you choose one of the following:

- A fixed gear setup. Learn how to spin on the descents, and how to negotiate corners safely. (Consider switching to some narrow clipless pedals, in spite of your preference to the contrary, and choose a frame with a high bottom bracket.)

- A single speed. (Accept the necessary complexity of two brakes.)

In either case, choose a gear ratio that allows you to cruise fast on the flats like you enjoy doing but still be able to handle the climbs. Since you like to sprint, this is doable. It will be a ratio a little lower than ideal for flats and quite a bit higher than ideal for moderate climbs. Long, steep climbs might be out of the question, but this is a sacrifice we sometimes have to make. I have a bike like this and really love it. Admittedly, it's one of four in my fleet, and I wouldn't want to settle for it as an only bike, but as I learn to play by its rules, it's turning out to work quite well for me. (It's a lot more fun than the 3-speed.)