Interesting. My husband used to always have me pump to 120. Lately he just got me switched to 105 in the back and 90 in the front, saying that the lower pressure helps reduce flats, which sounds opposite of what others were saying. He just knows he was the only one not getting flats on a long two day ride when he actually forgot to pump his tires BOTH days. He says it's been a really long time since he's gotten a flat. Far longer than he's ever gone without one. He used to keep the tire pressure up for speed and was anal about it, but while speed is always of mass importance to him, I'm guessing he figured out the tire pressure of that difference doesn't affect speed so much. Stopping to change a flat definitely affects speed, though!