Wrong saddle maybe ?
 

I’ve been riding a Selle Anatomica for a couple of years now and usually pretty happy with it until lately. There seems to be some consistency that once I start approaching 100 miles (or so) I start getting sore.
Now obviously that type of mileage is not a ride around the block but I’m wondering what other saddles out there might have a better reputation for long hours ?

I always figured that I might not like a saddle that feels okay up to 100 miles or so. Lots of things seem to happen at 100 miles, like my shoes tighten up.

Could the leather be stretching a bit?

Where specifically are you sore?

Surface abrasion? Solution is with lube and bib pad and possibly lowering too high a saddle (wiggling side to side when pedaling due to too high a saddle)

Pain between sit bones and the front (taint): can be incorrect saddle tilt, incorrect setback, too much reach to the bars, or simply get a saddle with a cutout

Deep tissue at the sit bones: More tire and lower pressure helps. More miles help. Genuine leather saddles like Berthoud and Brooks are probably the best when broken in and properly cared for. Brooks B17 for more upright sitting position and Berthoud Aravis or Galibier for more racing positions although Brooks was a Swallow or something for aggressive position but I have no experience with it. Once partially thru the break-in period, I rub lanolin, just a quarter sized area into the sitbone mark. The underside gets snowseal and a very, very light layer on top and buffed off but not the sit bone area. I am sure this is not the standard practice but the saddle then is customized to the sit bone spreading the pressure over a larger area than plastic saddles. I have a bunch of $300-400 plastic saddles that are "ok" but nothing comes close to an all leather for my butt

Stand Up More on Long Rides.