Well, I installed the Conti TT 28"X! 1/4" no problem. It might have just been the difference between the Conti's (75psi max) and the Specialized Nimbus 700X28C I took off (100psi max), but the rolling resistance was terrible. The Conti's rode smoother, but pedaling them about kicked my but. I just bought Specialized Armidillo 700X26C (max psi125), installed them, and went for a short ride. They roll a lot easier than either of the other tires, and even though the ride isn't as smooth, I like them. Guess tthe next step is to get a faster bike.