I usually do 4-5 organized week-long bike tours. The average age is 55-60 years old. There will be people going faster and slower than you. If you get in with the regular touring crowd, there is usually someone who illegally drives from city to city on the route. They take turns, so someone can cycle 1/2 the day, or every other day. I usually see about 2-3 cars who do this. As a warning, you can be "kicked off" the organized ride. If everyone has a spouse who drives the route, the regular low-traffic route can become congested. 50 miles a day is a breeze, even if you don't train for it. It is only 5 hours of riding. If you leave by 8:00 am and are back in camp by 5:00 pm, you have 9 hours to cycle 50 miles. It is a leisurely route. My advise for a newcomer is to try to cycle about 1/2 of the days mileage before you start taking 1/2 hour or hour long breaks. It sounds like your training program is excellent. You should not have any problems. The more you train, the more you will feel like dancing at night when the organized tours have entertainment. Good luck. (almost 50)