Yesterday I took a 32mi ride on the Serotta with my club. Didn't do the whole ride with them, picked up the ride as it passed through my neighborhood (the advantages of living in Allen Tx is that a good number of the weekly PBA rides roll through town) and jumped back off as we came through on the tail end of the ride. Had to work on staining the new front door for the house yesterday so I couldn't get in the full ride.
This morning I was back up early working on the door again (top coat) and after the first coat of clear I took a nice hour long ride on the Schwinn Crosscut along with my wife on her Townie. After dropping the wife off back at the house, I took another 45 minutes or so out on the Schwinn. I think I've concluded that my old SPD shoes are good for about up to an hour at lower speeds, but trying to really push it much and my knees / legs start complaining about not having my good specalized shoes on.