07-25-2018, 08:31 AM
There's a common misconception that skinny tires at high pressure are more efficient. This is only true on a smooth surface like a track. Anything rougher than that, the new consensus is that you are better off running at lower pressures with wider tires. Most World Tour teams now run on 25mm tires universally, and even wider (up to 30mm) in certain races like Paris-Roubaix where they are dealing with even rougher surfaces.
The benefits seem to be two-fold. First of all, with lower tire pressures, the bike is able to travel more smoothly over the surface due to flex in the tire. This means less energy is wasted in vertical motion of the bike and more of it is directed to horizontal motion. The second benefit is that the increased comfort for the rider means less energy wasted gripping the bars, engaging the core, etc. over the rough terrain and more can be directed toward pedaling. From direct experience, I can say that the second factor is considerable, but difficult to quantify.
The benefits seem to be two-fold. First of all, with lower tire pressures, the bike is able to travel more smoothly over the surface due to flex in the tire. This means less energy is wasted in vertical motion of the bike and more of it is directed to horizontal motion. The second benefit is that the increased comfort for the rider means less energy wasted gripping the bars, engaging the core, etc. over the rough terrain and more can be directed toward pedaling. From direct experience, I can say that the second factor is considerable, but difficult to quantify.