Proper air pressure can make all the difference
There are a lot of questions out there about how much air pressure a road bike tire should have. Proper air pressure is a hot topic among wheel and tire manufacturers and triathletes alike. Most of the major companies have invested time and money into testing what is really faster. Nearly every test had the same results. Most people were a little surprised about the results.
The tests showed that the pressure that had the least amount of rolling resistance was actually around 90psi. The general rule of thumb (up to this point) was the higher the pressure, the less resistance you had. People aired their tires up to whatever the tire was rated. Tires bounced on the small bumps that pavement has when they were aired up to more than 120psi. This bouncing caused the tire to lose momentum and it took more effort to keep the tire going at the same speed. When aired up to 90psi, the tire deformed over the bumps and kept the momentum going.
This same result also showed up when using 23mm tires versus smaller, “faster” tires. The 23mm tires deformed over the bumps and the 19mm tires bounced on the bumps.
If you’re going with the experts, then roll with 90psi. If you feel like more air is better, despite the testing, it’s still best to keep it 120psi or under.