i mean, im not very experienced, but im my limited experience atleast for myself, i find that im more comfortable carrying a higher gear at a lower rpm ( i try to stay in 75-85 range) but if i drop two gears and spin at like 95-105 im still not going as fast and by no means am i saving energy, my heart rate goes sky high. so im faster, and more relaxed in a higher gear. but from what ive seen, its based on different leg muscle builds. i have very very strong quads and im a bigger guy, so im more comfortable with a heavier gear and slower rpms. but hey im still more or less a noob.
-rOOster-