I am racing on Veloflex Criteriums in 23 this year and I love them. 105psi in the front and 115 in the back and I weigh 200LBS but I like the feel of a squishy tire in the corners and they take bumps like shock absorbers. My team is getting a deal on Challenge's so I'll probably try them out. I'd like to get a decent tubular in 25 for an even more squishy road hugging feel. I find the Continental sprinter to be on the very low end of quality for a racing tire. They work ok and last long but they don't give you the feel that you get from better tires but then they are half the price too.