Needing a rest day depends on several factors, and is similar for road and touring cyclists:

• Age/recovery time;
• Topography;
• fitness level/health/injuries;
• Weather/wind;
• Length of ride/daily mileage.

These are all related. Any single or combination of factors could require a rest day.

Recovery time time takes longer as people get older. In my mid-thirties I rode a loaded 1,100 mile tour in 11 days. When I was 64 years old, my wife and I rode across the U.S. averaging over 50 miles per day in 72 consecutive days. Now in my 80s, the daily mileage is shorter, rest days more frequent and recovery takes longer. In my experience, I have found when I exceed a personal threshold where I am digging into my reserves requires an easy day or rest day(s) to regain my optimum output level.

My wife and I are training for a tour next summer, and use the hard /easy day method of building strength and endurance. We have ridden across Canada from Vancouver Island to Toronto, and want to finish the ride from Toronto to Prince Edward Island.