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Interbike: Retul Frame Finder

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Retul’s motion capture system lets bike fitters measure and fit riders with unprecedented accuracy, and the small company out of Boulder, Colo. has once again released a piece of technology that helps a rider get comfortable on a bike.

Retul fitter Todd Carver says that the motion capture system provides all the information needed to fit a rider perfectly on a specific bike, but Frame Finder allows the fitter to “complete the fit process” and use the fit data provided by the Retul motion capture system to select the ideal frame and aerobar combination for an individual’s fit.

Frame Finder is a web app that graphically overlays the fit dimensions of real-life bikes on top of a rider’s personal fit coordinates. If a bike’s seatpost can move up and down 10 centimeters and back and forth 4 centimeters, Frame Finder creates a rectangle that is 10 x 4 centimeters to encompass every potential saddle position. It does the same for stems, aerobars and saddles to depict every possible fit configuration. Currently, their database is sparse but Retul will gradually add bikes and components to their database until nearly every possible combination can be depicted in Frame Finder. The process goes like this:

1. The rider is fit to their optimal position

2. The fitter uses their Retul Zin tool to measure the saddle, bottom bracket and handlebar locations in space, which represents the rider’s fit coordinates.

3. The fitter uploads the coordinates into Frame Finder and selects up to three potential bikes.

4. Frame Finder displays rectangles about the saddle and handlebar positions that represents the               potential fit ranges of the selected stock bikes.

5. The fitter can then swap any parts to change how the bike fits and compare the altered bike geometry to the rider’s position.

Swapping frames, frame sizes or components within the program lets the rider and fitter see which bikes can accommodate their position and which bikes fit best without compromising handling or stiffness by stretching a bike’s fit limits.

Graphically representing fit in this way takes the guesswork out of finding a bike and component combination that accommodates each specific fit.

The FIST bike fit system uses stack and reach dimensions to quantify a rider’s fit, and this system does an excellent job translating fit dimensions into a properly fitting frame without having to measure bikes by hand. This method is limited, however, because it does not account for the impact of the components on fit. Replicating a position using stack and reach requires the cyclist to use the same components that were used during the fit unless the fitter has pre-built bikes to measure, in which case they can physically measure a complete bike’s stack and reach to any specific point. Frame Finder accounts for the influence of the frame and the other components without measuring a bike.