It was in about 1978, the Minnesota Ironman. It was on my first 10-speed, a Japanese "Crystal" heavy old thing. The last 10 miles or so were really tough, followed immediately by a long long bath. I've done a lot of 50-60 mile rides since, but was never motivated to notch a century. Now in my 50th year, after getting back into biking seriously last year, I plan to do my second one.