In order to make the best fit recommendations, the fitter must realise that the front and side views are actually interdependent reference points. In other words, the front and side views must be viewed simultaneously in three dimensions in order to see how all the applicable movements of the body are working together.  Retül uses a 3D motion sensor to simultaneously gather data on multiple angles of the rider.

Retül technology is a cycling-specific motion-capture bike fitting system designed to provide qualified bike fitters highly accurate and comprehensive bike fit data. The system incorporates three-dimensional measurement (1), immediate report capability (2), and a millimeter-specific digitising tool (3) to provide the most accurate dynamic fitting solution in the industry.

The Retül system reads the rider's movements while they are in motion on the bike, and accounts for all three planes of movement (3D). This type of data cannot accurately be captured with 2D video, static fitting, or eyeball fitting. The Retül system eliminates the guesswork and assumptive nature of bike fit. The result is that the rider will have a true fit to his or her bike, maximising efficiency and performance while avoiding discomfort or injury.