Okay, per all your expert advice, I adjusted the nose of my bike saddle down a fraction today and took it out for a 90-minute ride to see if that would help my little problem with Razor Blades in the Crotch. Maybe I have a weird pelvis or something, but I can get the saddle to fit sitting up, or I can get it to fit in aero position, but not both. So we're choosing aero position and reserving the uncomfortable angles for periodically sitting up and stretching only. Hopefully that will work.
I worked on repeated intervals of 1 minute high-cadence (95-105 rpm) and 4 minutes regular cadence (80-85 rpm). I tried to really push it and got up past 23 mph range during the high cadence intervals with a tailwind, which is pretty speedy for me on the flat! However, average speed came out to be just 17.1 mph over 22 miles.
I love tailwinds.
No razor blades today! Then again, it was "only" 22 miles. The razor blades spontaneously emerge from the saddle at about 70 or 80 miles. I'll see how it goes on the next long ride.
Note to self: Stop forgetting your heart rate meter! You need it so that you don't get discouraged riding into headwinds.