I'm 73, been seriously cycling for about a year. I've gone from 186 when I started to 161 in about four months and maintaining mid 160's. Had an "off" last February; fractured a clavicle and was off the bike for five weeks. My per week mileage has increased from 50-60 miles per week before the fracture to 70-80 miles per week, currently. BUT... my "average speeds" still don't quite equal my times before my crash. I give myself a day to recover between rides so I only ride every other day and I've noticed I don't recover from my longer rides as quickly as I used to. Gonna' keep on truckin' in the hope that speeds start show some joyous increases!