The effect of circular and non-circular chainrings on pedal power output, bicycle handle-bar and ground reaction forces at different slopes

The Effect of Circular and Non-Circular Chainrings on Pedal Power Output, Bicycle Handle-Bar and Ground Reaction Forces at Different Slopes The oval chainring is an equipment used in cycling and it has been improved for many years with the intent of enhancing the pedalling dynamics. It is known that different oval chainrings have improved some performance parameters. The aim of this study is to demonstrate the power generation of round and oval chainrings used in the cranksets of bicycles on different gradients and their effect on the force applied on the ground (front and rear wheel), to analyze the forces applied on the handlebar of the bicycle by depending on the gradient and also the crankset factor, and to reveal the potential differences.10 male trained athletes on elite level with values of 65,5 ± 5,73 mL·kg-1·dk-1 Vo2max have participated in the study (372,22 ± 47,44 watt, 196,78 ± 5,89 heart rate). The tests were performed using different gradients (started from %1 gradient to %5, %10, %15 gradients, single session for 15 minutes) with the mountain bike located on the fixed bicycle roller fixed on a treadmill (treadmill speed feature not used ) up to 15% gradient. Athletes have been directed to perform at the 70% (260,31 ± 35,49 W) of the power output corresponding to their Vo2max values in round and oval tests. During the test, data of the pedal dynamics [power phase start (pps◦); power phase finish (ppft◦); peak power phase start (ppfs◦); peak power phase finish (ppff◦)] collected by Garmin Vector2 and data belong to applied force on the ground, handlebar, collected by loadcells. They have performed at a pedalling rotation speed of 74,56 ± 4,25 rpm. Significant differences have been found out in values of pps(◦), ppfs(◦) and ppff(◦) (p≤0.05) on all gradients between round-oval. On other parameters, no significant differences have been detected (p>0.05). On all gradients between round-oval, no significant differences in the forces applied on the front wheel, the central zone, the rear wheel and the handlebar have been detected (p>0,05). The oval chainring has created a difference against the round chainring only in pps and ppf on the gradients of 1%, 5%, 10% and 15%. When putting the findings into practice, the pedalling dynamics of every single athlete must be thoroughly analyzed so that a choice for the crankset could be made accordingly. Keywords; pedal dynamics; bicycle climbing; strength; performance; garmin vector