Some answers about Retul – Bike Fit
OK, I’ve been getting a little help with the website, trying to keep it going with information, and new input. He posted an article out of VeloNews yesterday, that I thought was very interesting. If you missed it, the link is here. I think two things about this article, a: that Kit hits the answer right on the head; and b: it’s very reminiscent of an article by Dan Empfield of slowtwitch.com about 3 weeks ago. Of course, both of them put out a lot of good information about sizing, and fitting, and how Retul sits in the picture. Both riders sum up that the skill is in the fitter, and that a good fitter with old tools is better than a bad fitter with good tools. I think that this is pretty simple logic. Where the decision has to be made is when you have two fitters of comparable knowledge and experience, does the tool make a difference? Absolutely. Should I spend the extra $100 to get a dynamic (Retul) fit over a static measure fit? Look at what you have on your bike that you paid $100 (or more) for, and know that a good fitting will make a bigger difference than any 1 piece on your bike. Kit and Dan also sidestep a couple other key points on this topic, which I’ll address below.
First let’s tackle two of the things that glared at me from Clod’s question to Kit. He asked “will we get within of 1 cm or less on either size of this fictional perfect bike fit?”. First I’d like to debunk this notion of the fictional “perfect bike fit”. As humans, are bodies are constantly changing. Sometimes small changes, sometimes large, but we all change on some scale all the time. So, if that’s true, how do we as bike fitters prescribe a certain position to a body that is going to change? The answer is that we put the body in a snapshot of a great position, and hope that the customer comes back, when they know that something major has changed, or that enough small changes have taken place to know that we need to change the position on the bike. Which begs the question: “What differentiates a small change from a big change?” Well this leads me into my second point about Clod’s question, where he’s concerned with getting within 1 cm of this position. While 1 cm sounds like a small amount, in my world, that’s a big measurement, as most riders can feel a 3mm adjustment. I’d like to think that I can get within 1 cm more than 90% of the time without any tools. With the static measurements, a good fitter can put you in a really precise position, usually within 2-3 mm.
What is so exciting about Retul is threefold. First, the measurements are dynamic, in other words, while you’re pedaling. What this means, is that we no longer have to watch what your pedaling technique is, and then make adjustments for it. The Retul will show us the angular measurements of the body all at once. This gives us a much clearer “big picture” of the cyclist. As an example, if I move a person’s saddle position, and I want to see how that affects their open hip angle, and their knee extension, I have to take 2 static measurements. The likelihood that my customer is going to hold a static position, without moving long enough for me to take 2 measurements is not very good. Couple that with the fact that the customer is probably not going to stop their body in exactly the position that it would be in while pedaling, and you can start to see that we will start to have discrepancies in our measurements. That is why, when measuring statically, a good fitter will have you pedal after making adjustments, so that they can see with their eyes, what your whole body is doing, dynamically. With the Retul we have quantitative measurements of where your body is during the pedal stroke.
The second really exciting thing that the Retul allows us, is to see things in different ways than we have before. For example, while the rider is pedaling, we can look at a stick figure pedaling. This allows us to see certain things more clearly, such as how much hip vertical travel a rider has, or what ankle angulation looks like throughout the pedal stroke. The other piece of the pie is knee tracing in the frontal plane. There are other tools that allow you to see the knee path, but Retul actually records the knee path for every pedal stroke, and displays it graphically. This allows you to not only see where the knee is going, but how consistent it is being. What I am currently finding is generally that the more comfortable the person is the more their knee stays in the same path.
The last really exciting thing about the Retul is something that Dan Empfield touches on, and that is the ability of the Retul software to adapt, and to track trends, and share information. In other words, as we find new measurements that become valid (this happens relatively often) the software can be adapted to display those measurements. Also, because the Retul software saves the fitting data, we can see if there are trends developing in our fits, and (with cooperation) compare against other fitters, to see if we are staying true to our own methods, or if trends are developing in fitting. Also, if we see something that is just “out there” and we can’t quite figure it, we can share that fit with another fitter, and get a second opinion. In fact part of the Retul University certification is that we submit (without identifying information) 3 fits per year to be audited. This helps us to keep current with new science as it develops, and to make sure we don’t get into bad habits. All in all this might prove to be the most important feature of Retul.
I hope this has clarified some of the Retul information. Coming soon, you will see articles on both bike sizing and Retul vs. video capture.
