I found that I could acclimate so I wasn't sore after a 80-100 mile ride, but if I did 120 miles I'd be sore again. Or, if I could ride back-to-back centuries without pain, then adding a third would kill me. A 200-mile weekend was/is the limit of my training opportunities, so I would always hurt on tours. Now I ride a recumbent and none of that matters anymore. I can ride until my legs give out, the only thing I'll have to show for it the next day might be sore quads.