Finally got an official ride in on the 1985 Trek 620. I've been on about some 30/40 miles, but they were just pottering around. Today I rode about 50 miles, only stopping for a couple of water breaks.
Overall, the bike performs well. The 35mm tires do slow one down, no doubt about that.
On my previous rides, I had observed that the Berthoud Aravis saddle is absolutely rock hard. In addition to this, it is very flat longitudinally along the top, not having any sag.
By about mile 35, this was starting to severely bother me. In addition to general discomfort, the flat along the top was making it impossibly painful to ride the drops.
You do the geometry.
I pedalled along thinking about this, in the way that saddle discomfort demands attention and thinking about all the Brooks B17 saddles that were comfortable right out of the box. I was also thinking pessimistically about how long it would take to break in a saddle with leather as thick as that of the Berthouds.
Finally, I remembered observing that the saddle had come w/some built in tension, not fully loosened the way Brooks customarily are when new. So I stopped, pulled out the 5mm allen wrench and backed off the tension a full turn.
This had a pretty dramatic effect. I'm not going to say everything was immediately sunshine and lollipops but it was a lot better. After another 5 miles, I gave it another half turn of loosening which further improved things.
On this ride, it was a little hard to tell if this will yield an acceptable comfort level, as I was pretty beat up and sore by the time I got around to detensioning the saddle a bit. But I am a lot more optimistic about it than I was midway through the ride.