Well, I've gotten two more rides in on this. An aborted ride of only 21 miles and then 31 miles today. I still don't know what to think. It's comfortable but my pace is really slow on it. I've dialed in my normal fit on it so that is not an issue. I don't know if I'm maybe sick or if there's a lot of resistance somewhere in the drivetrain still. I'm still running those old tires but I can't believe that my prefered GP4000s tires will make a huge enough improvement to get me back to my normal pace.