As a junior rider in the mid 80s, I attended a road racing training camp at the Olympic Training Center in Colorado Springs hosted by the USCF. I remember the head coach Eddie B (Borysewicz) speaking about the importance of proper bike position. Later, when we were fitted on our bikes, I noticed that a simple measuring tape and plumb bob were used to determine saddle height and set-back. We were warned that these measurements were error-prone and that we should add a few extra few millimeters to the saddle height measurement in order to get close to the correct position. The fitting procedure I learned at the Olympic Training Center I kept with me for many years and continued to use it while working at bike shops and on my own bikes. It was frustrating at times. I would take 2 or 3 measurements and make sure that everything was lined up, but even then it was impossible to get the saddle height exactly the same on two different bikes, just an approximation. I could feel it in my legs: something was different between the two bikes, but I was unable to detect it with the simple tools I had. A few years ago, I decided to order my first custom frame. The frame builder needed many measurements from my old bike and told me to make sure they were accurate and to take them at least 3 times. That is what I did, only to find that some of the most important measurements such as saddle height and set-back were difficult to get accurately. The measurements were always different by 2-4 millimeters. I thought to myself, "This is crazy! I'm spending all this money on a custom bike, but I'm not even sure about the measurements I made on the old bike." I ordered my frame but also began work on the Saddle Jig. Now I have four road bikes. When the Saddle Jig was finished, I used it to adjust the saddle on all of them. Sure enough, I found out that the saddle height had been off on all four bikes by 3-4 millimeters too high or low. What a difference it made to use the Saddle Jig! Now each bike feels exactly the same. No more guessing.