Where a Retul Bike Fit Fall Short

A Retul bike fit generally has a reputation for being above average primarily because the infrared technology does a good job of measuring the rider in all three planes. But just as with any bike fit technology, just having it doesn't assure the fitter or rider of an excellent outcome. There are many places out there using this technology and performing poorly with it. But in this video and article I want to explore some of the blind spots and shortcomings of the Retul bike fit system as a whole.https://youtu.be/ZQNb4-eDCXkSome may be surprised to learn that the Retul bike fit system has shortcomings. It's not perfect and in fact there are a number of areas where in certain situations I might switch to an alternate measurement technology (like high speed video) in order to nail down what's going on at a deeper level.Many of the problems stem from the foot and ankle measurements. There are some good measurements in there, but you need to know what you're looking at.For instance, there are "Ankle Angle Minimum" and "Ankle Angle Maximum" and "Ankle Angle Mean" which in general try to make known what position of dorsiflexion (toes pulled up) and plantarflexion (toes pointed down) the ankle and foot are in. The main problem lies with the fact that there is no information on where in the pedal stroke these minimum and maximum ankle positions happened. This is important because there are a number of important ankle postures that can spell trouble for efficiency, stability through the feet and hips, and general power production ability in the pedal stroke.  Because none of these measurements are location-specific it makes the "mean" measurements even less useful -- all it represents is a running average of the rider's foot position. This isn't terribly useful.Additionally the placement of the centers of rotation for the joints is done ahead of time and then we attach the infrared LEDs to these spots. The problem with this is that the actual centers of rotation for the joints changes as we move through the pedal stroke. So the center of rotation for the knee will be slightly different at the top of the pedal stroke versus at the bottom. So this will affect the numbers we get from the infrared. This usually doesn't play a huge role in a bike fit for a couple reasons. First the "error" this might produce is usually pretty small -- in most situations less than a degree -- and we're using the infrared for most or all of the measurement anyway so when we make a change to the rider's fit and re-measure them we're still getting a good apples to apples comparison of how they were moving to how they are moving now.Take a look at the video and let me know what you think. Even though the Retul bike fit system has gray areas such as these it still beats the other technologies out there in my mind. And even though I do occasionally employ high speed video to peek more closely at certain things the Retul might miss, I'd still not prefer to use video full time. It's much too finicky in the setup and much too cumbersome to get anywhere near the number of measurements I get with the Retul in any reasonable amount of time.