what's the reasoning behind it? It is an attempt to improve pedalling efficiency. Some abstracts to the research can be found at: http://www.ncbi.nlm.nih.gov/pubmed/2625415?dopt=AbstractPlus http://www.ncbi.nlm.nih.gov/pubmed/16901493?dopt=AbstractPlus Here is an alternate view (cut 'n paste) because it was posted on a closed forum so I can't post the link: BioMechanics November 2006 Researchers target cleats, fatigue to improve cycling performance By: Jordana Bieze Foster If it prevents a cyclist from maximizing the transfer of power from foot to pedal, it is the cyclist's enemy. Research presented in September at the annual meeting of the American Society of Biomechanics, however, suggests that sport science may be closing in on those enemy ranks. The inability to generate power during the recovery phase (from 6 o'clock to 12 o'clock) of the crank cycle is one critical obstacle standing between the cyclist and the goal of 100% pedaling efficiency, or maintaining power transfer throughout the entire cycle. Researchers from Ball State University, however, believe that repositioning cycling shoe cleats can alter foot and ankle kinematics to improve power output, produce a smoother stroke, and increase pedaling efficiency. The investigators analyzed 10 competitive male cyclists under two cleat placement conditions: the conventional placement with cleats under the forefoot, and an experimental condition with cleats positioned under the heel. They found that the heel cleat position was associated with a significant increase in pedaling efficiency (77% versus 73.4% for the toe position), which is likely a result of significant changes in ankle kinematics. Most notably, the mean ankle angles during the last 90 degrees of recovery and the first 90 degrees of the power phase were significantly lower with cleats in the heel position than the toe position (see table); this meant that ankle angles in those two cycle quadrants were closer in magnitude to the angles in the other two quadrants, resulting in a smoother overall stroke. "So much of cycling is about equipment. This is a way we may be able to increase performance by involving more of the human component of cycling," said Jeff W. Frame, a former graduate student in the university's Biomechanics Laboratory, who presented his group's findings at the ASB meeting. "In the heel position, it's much easier to pull up on the backstroke, which is what cyclists try to do to improve efficiency." Peak power output did not differ significantly between the two cleat positions, but the researchers believe this may be because the study subjects only had 15 minutes to familiarize themselves with the new cleat position, Frame said. Along with loss of power transfer, fatigue can also affect pedaling efficiency. Elite cyclists compensate for the effects of fatigue by making kinematic adjustments that allow them to maintain power output, according to findings from the University of Texas in Austin. Researchers assessed lower extremity joint angles and trunk lean in 10 elite male cyclists who pedaled to exhaustion on a cycle ergometer set at a workload equivalent to each subject's maximum oxygen consumption. They found that the only change in range of motion that occurred following the onset of fatigue was increased trunk flexion angle, which may represent an effort to maintain power output by increasing the stretch response of the hip extensors. "The angles that are least constrained are the ones that changed the most," said Jason E. Joubert, a graduate student in the university's kinesiology department, who presented his group's findings at the ASB meeting. Ankle angles also tended to decrease with fatigue, but the range of ankle motion was varied, increasing with fatigue in some subjects but decreasing in others. Shifts in trunk motion varied between subjects as well but ultimately shifted toward the aforementioned positive trend. "As fatigue set in, we saw a lot of shifting," Joubert said.
