A few years back, I did the 7.5 mile Potomac River Swim with a buddy and had a good time. Needing some motivation for swim training this year, I decided to give the race another go. This time around wasn’t quite as fun as the first time, but it was a good learning experience.

Six weeks after the marathon, a test of the biking legs (and swimming arms and remaining running legs) was in order. I had signed up for Kinetic Half...