For my first seven years as a high school Cross Country and distance coach, I sat in my office, staring at different spreadsheets, figuring out which athletes
should be running what speeds during workouts. It always worked very well, but it was ineffecient to look at race times, then at another chart of training values, and then at another chart to fill out the results. I started work on a spreadsheet program that would automatically calculate all of the information I was looking for, but I couldn't figure out the equations in the program. Then at church on Sunday morning, I had a revelation: use a circular calculator with all the data already figured out!
I started designing the wheel using the spreadsheets I already had, and made a simple wheel for my cross country team and introduced it at practice the next day. I made paper copies with brass brad fasteners, and handed them out to each ability group and had them figure out their own intervals. The kids asked where I got it, and when they found out that I made it myself, they encouraged me to market it. With the input of several other running coaches, runners, artistic-types, and my wife, I recalculated the data based on the research, redesigned the face of the wheel, and started printing them.