Resting in the shade. I feel a lot faster on the road on my triathlon bike than on my mountain bike. Since it's very light, efficient, and aerodynamic, I feel like I'm cutting through the wind. With every stroke of the pedal, I can feel it transfering it into a burst of power. I estimate that I'm getting a boost of 5-6 mph over my mountain bike on flat roads. On downhills, it's much faster. On uphills, I feel very quick and nimble. Even on flats, I can maintain a higher cruising speed for much longer. My only complaints so far is that it's hard on my back when I'm riding hunched over in aero tuck position. I also feel muscles burning in my legs, perhaps because I'm riding in a different position. Triathlon bikes are different from road bikes because their geometry is designed to be more aerodynamic and also less draining on muscles used for running. They will help save your legs for the final running portion of the triathlon.