Thanks for the responses. I have been very fortunate. 34 yrs running on the road--over 71,000 miles. 16 marathons (Boston Qualifier--age 65 3:57 in 2008) and numerous ultras. I just got back on a bike after 13 yrs. Have been running 45-50 miles per week for a lot of yrs. Developed AT as a result of a wart being removed from the bottom of my foot in late Feb. Foolish me, kept running and racing with a gimp. Swelling and pain stopped me completly a couple weeks ago. Bought a new Trek 7.3 hybrid 1 month ago. I have ridden over 700 miles and feel great. It doesn't bother my Achilles and I now can walk w/o a limp. I have been amazed that I could rack up that many miles. Have done several 50 milers, a bunch of 40's and last week did a 67 miler. I love that my recovery is so quick. I guess my thought is a ratio of 5 miles biking (14 mph) is equal to about 1 mile running (9+ min miles). I have found it very difficult to coast when running. I miss my running, but I am glad to be back on a bike. Yrs ago I crosstrained with a road bike , then a mtb and ran 40-50 per week. Was in my 40's and early 50's. Was very fit. The biking made me a stronger runner. I plan on continuing biking even when I can run. I have bought so much gear. Actually have spent 2x as much on clothing/matching gloves/helmet/lights,etc. as I did on the bike. Having fun.
Again, I really like this forum and am learning a lot about biking. Nick
PS Retirement is great! I have found it beats working. Much more time to play.