Author and graduation date: Lisa M. ZIEMBA, May 1998

Committee members: Peter R. Francis (Chair), Patricia Patterson, Paul Kolen

Thesis title: The Effects of Changes in Crank Length, Stem Length, and Seat Height on the Lower Extremity Kinematics of Experienced Cyclists

This study examined the effects of changes in crank length, stem length and seat height on the lower extremity kinematics of three competitive triathletes (two female, one short and one of medium stature, and one male, tall stature). Each subject was "fit" to his/ her own bike using the USCF guidelines, 1 year prior to the investigation. Longer and shorter crank lengths, and higher and lower stem and seat heights were investigated. All subjects were videotaped during 27 different conditions while riding his/her own bike on a Computrainer. Hip, knee and ankle joint angles were recorded (and the data analyzed) using the Peak Performance Analysis Stem (Peak 5). Heart rate, comfort levels and power were also measured and recorded.

As comfort levels decreased, joint angle increased for Subject 1 (short), indicating a preference toward a more compact position with smaller joint ranges. Subject 2 (medium) showed similar results to those found for Subject 1 for the knee and hip joints, but ankle ROM decreased as her comfort level decreased. Subject 3 (tall) showed an inverse relationship to that of the short and average sized subjects. As comfort level decreased for this subject, joint angles decreased as well.

The results suggest that each individual cyclist's anthropometry, riding biomechanics and style must all be taken into consideration when fitting a cyclist to a bike, and that comfort is of utmost importance for the endurance cyclist. Future study should be directed toward utilizing direct measure using on-line goniometers synchronized with a device that monitors crank position, and simultaneous monitoring of oxygen uptake.

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