Originally Posted by dingadinga

By reading reviews in Amazon, I found it interesting to see that many people gained speed from stock tire to a better tire, e.g., Continental GatorSkin tire, as much as 10~15%. If that's true, I guess it would be the single most important and cheapest upgrade. Is this a common knowledge? If it is the case, I feel so stupid that I had spent all the money on upgrades (bike, wheels, components) except the cheapest and most effective way.