Getting a proper fit on your bicycle is the most important aspect of your riding experience. It can make the difference in success or failure and at the very least a proper fit will increase your speed and efficiency greatly.
Sunshine Bike Shop is proud to announce we've just acquired the Dynamic 3D Retül fit system. The same system that the USA Triathlon recently announced as using Retül as a technology supplier to the national team program for training for the 2008 Beijing Olympics. This system was previously only available in one other place in Missouri, but now it's here in Springfield, and only at Sunshine Bike Shop.
What is the Retül system and how does it work?
Retül technology offers 3-D Cycling Gait Analysis using state-of-the-art motion capture technology originally designed for the surgical navigation industry. The same accuracy standards used by medical professionals who are performing brain and other noninvasive surgical procedures are now available for precision bicycle fitting.
 The system is similar to that used for motion capture for motion pictures or video games, but employs a harness of eight LEDs (Light Emitting Diodes) instead of reflective markers.
The LEDs are placed in key body movement locations for bike riders and tracked by three infra-red cameras resulting in three-dimensional measurements accurate to fractions of a millimeter.
The measurements are taken nearly 500 times per second!
“It's really an incredible evolution, of sorts, in terms of technology,” said Allen Lim, PhD, the sports physiologist for the Slipstream Pro Cycling team, about the Retül technology and software. “This is like a stock broker going from a ticker tape to the Internet.”
 Bike Fits Must be Dynamic
Most bike fit specialists fit riders in a static position. This is because the traditional tools of the trade like tape measures and plumb bobs that don’t allow accurate measurements while the rider is pedaling. Retül captures the rider’s position relative to his pedaling motion, and therefore creates the most realistic replication of the actual pedal stroke and body position when out on the road and trails.
Measurements Must be Accurate
Measurements made by traditional tools have one thing in common: they are subject to human error and therefore can be devastatingly inaccurate. Even slight inaccuracies can completely change the rider’s feel after a ride. The general rule is that if you feel pain, something can probably be changed to eliminate that pain. Retül uses motion capture technology that accurate to within less than a millimeter, creating true objective data which can be utilized by the right fitter for the perfect biomechanical fit.
Frequently asked questions about Retül?
Why should I get a Dynamic 3D Retül fit?
Primarily, because the fit is dynamic, not static. The data sample is taken during an active pedaling cycle and gives you the most information about just what is happening while you are in motion, and in 3D, so we get both vertical and lateral movement at the same time.
 How long does a Retül fit take?
Depending upon the process the fitter is using, an average fit with Retül runs 90-120 minutes, but if you have major adjustments or component changes, it can stretch longer than this.
How can a Retül fit help overcome and/or prevent injuries?
The key to applying knowledge about injury prevention is having the best data available. With the system's capability to track and monitor all 8 LED locations simultaneously, the movement of the body is tracked very specifically and with applied knowledge of kinesiology and bio-mechanics, in addition to rider provided information and feedback, a Retül fit can establish a final bike set-up that reduces injury opportunity and corrects injury-causing positions.
What if I want to transfer my fit to another bike/ bikes?
The software establishes a file for each rider, and within that file, the bike and final fit data is stored by each bike the rider would like to be fit to. The client receives a printed report of the final fit, so with an understanding of frame geometry differences and proper measuring tools, the cyclist can duplicate the numbers themselves on a new bike, keeping in mind that different types of riding may require different rider positions.
Retül is accurate
The software is designed specifically for bike fitting. All rider interview and fit data is stored in client specific files, which can be accessed at any time to compare previous fittings with new data.
Readings taken throughout the Dynamic 3D motion capture process are immediately processed and a report generated. The fitter then analyzes the date from this sample and evaluates the need for position change. Once the changes are made, the process is repeated to verify effectiveness. This new data then becomes part of the final report, in addition to post-fit bike and equipment measurements.
The software can track information for multiple bikes (i.e. via a bike name) for each client so that fits across categories, i.e. road, mountain, cross, etc., are distinct. A historical Position Report can be generated at the push of a button from any of these files for quick comparison or reference. Our goal was to create useful software that collates and keeps information organized for maintaining client history and easy accessibility. In active use, the software is user friendly and will not detract from fitter/ client interaction.
Retül is Active
The system uses infra-red LEDs (light emitting diodes) that get placed on the body in specific skeletal locations. Active systems differ from passive systems in that the tripod mounted LED sensor is tracking the light directly from the source (the LED diodes).
Passive systems use reflection (light returned to its source via a material that repels the light source) to track markers. The problem with reflection is that many shoes, clothes, bikes, and other objects have a lot of reflective points on them, so false images known as artifacts get picked up by the system. In most cases, the user has to go into software, distinguish between the desired markers and manually delete these artifacts. In a shop with windows and shiny bike parts everywhere, this can be highly problematic, as covering all of those sources is a near impossibility, requiring the time consuming removal of artifacts before data collation can begin.
Retül's active system does not suffer from this problem. The active system flashes each LED discreetly as the infrared light travels from the LEDs on the body points to the sensor on the tripod. The sensor then triangulates the position of the LED in true 3D space. Our system can track these points to within a millimeter of true position. Data collation is immediate and fast.
Retül is Fast
The system flashes an LED every 2.1 milliseconds. That's 476 times per second or Hertz. The system takes a full set of body measurements every 34 milliseconds. That's 29 full sets of body data per second. Our sample sizes, taken dynamically, last anywhere from 5 seconds to 5 minutes ....whatever the fitter desires. The software processes all of that data in seconds, synchronizing the eight data points tracking them across longitudinal, vertical and horizontal planes.
Retül is Synchronized
Synchronization yields body location intelligence. The receiver knows what LED is flashing and where it is on the body. The software automatically, by skeletal position, identifies the proper LEDs for the measurements of each marker's position. This is virtually automatic, unlike in passive systems, in which the user must tell the system what reflection images are related to what marking point. There is no post-processing needed with Retül's software, so reports are accurate, 3D reports are generated immediately for viewing.
Sunshine Bike Shop has invested a tremendous amount of money in this state-of-the-art system because we're serious about helping you achieve the best fit possible. Come see us today and discuss how a Retül fit will take your cycling to the next level. It's another reason why we're Springfield's favorite bicycle shop!
Why buy from Sunshine Bike?
Information from Retül used with permission - Copyright 2008
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