Load equalizing mechanism for bicycle planetary gear system

Planetary gear systems are very compact and efficiently transmit large amount of power. Their advantages have resulted in the recent use of such systems on bicycles. When using a planetary gear system it is important to install a good load equalizing mechanism in order to produce a comfortable level of effort for a rider. Static forces acting on elements of a planetary gear system are calculated using a two dimensional model and the effects of load equalizing mechanisms, run-out and assembly errors of elements on planet gear load distribution rates are evaluated. The results show that in the case of three planet gears at least one element from among the sun gear, an internal gear and planet carrier should be movable in order to improve load distribution. The direction for run-out errors of the planet gears at their initial state should be in a radial direction to the center of the planet carrier. The circumferential position of the planet gear shaft should be composed with special attention.