Bicycle pedals that allow feet to twist in and out at the toes reduce stress on the knee joint, according to studies conducted at the UC Davis Cycling Research Laboratory. Knee injuries trouble cyclists of all levels, accounting for about one-quarter of all reported cycling injuries. Some injuries are self-induced from trying to do too much too soon. But others, called pathomechanical, are due to misalignment between bicycle and rider. Reports of this second kind of injury have increased with the popularity of step-in, binding-type pedals. Maury Hull, a UC Davis professor of biomechanical engineering and a cyclist who has suffered knee injuries himself, thinks these pedals may unnaturally constrain the foot and generate stress up the leg to the knee. Hoping to relieve this high-technology knee stress, Hull studied the three practical ways a foot could move in a pedal. Twisting reduced the largest number of knee stresses, compared to a swinging, tilting and fixed foot. This twist is found in a type of pedal known as a "floating" design, which has recently become popular with consumers but had not been tested scientifically. The research was funded by Shimano Ltd. of Osaka, Japan. Hull is now testing if the reduced loads to the joint actually reduce stresses in certain vulnerable knee tissues. With former graduate student Patricia Ruby, Hull sums up this and other work on injury-prevention technology in a chapter of "Hi-Tech Cycling" (Human Kinetics, 1995).