The application of the spine concept to handlebar shape is the result of fiziks research with riders of 3 uci world tour teams that were riding fizik saddles a correlation was found between the saddle shape each rider was using and the handlebar shape they were riding just as your choice of fizik spine concept saddle shape is guided by your degree of spinal flexibility and subsequent pelvic rotation fizik offers this same concept to find your most comfortable handlebar shape revie