Effect of Chain Wheel Shape on Crank Torque, Freely Chosen Pedal Rate, and Physiological Responses during Submaximal Cycling

Abstract

The development of noncircular chain wheels for the enhancement of cycling performance has been in progress for a long time and continues apace. In this study we tested whether submaximal cycling using a non-circular (Biopace) versus a circular chain wheel resulted in lower peak crank torque at preset pedal rates as well as resulting in lower pedal rate and metabolic response at freely chosen pedal rate. Ten trained cyclists (meanϮSD: 27Ϯ3 years of age, 182Ϯ4 cm tall, 77.5Ϯ7.0 kg of body mass, and peak oxygen uptake of 61.7Ϯ4.4 ml kg Ϫ1 min Ϫ1) cycled with a Biopace and a circular chain wheel at 180 W at 65 and 90 rpm for recording of crank torque profiles, and at their freely chosen pedal rate for recording of pedal rate and metabolic response, including oxygen uptake and blood lactate concentration. Crank torque profiles were similar between the two chain wheels during cycling at preset pedal rates. During cycling at the freely chosen pedal rate (being 93Ϯ6 and 93Ϯ4 rpm for the Biopace and circular chain wheel, respectively), blood lactate concentration was significantly different between the two chain wheels, being on average 0.2 mmol l Ϫ1 lower with the Biopace chain wheel. A musculoskeletal simulation model supported the idea that a contributing factor to the observed difference in blood lactate concentration may be slightly reduced muscle activity around the phase where peak crank torque occurs during cycling with the Biopace chain wheel. In that particular phase of the crank revolution, the observed slightly lower muscle activity may result from larger transfer of energy from the legs to the crank.

Influence of noncircular chainring on male physiological parameters in hand cycling

“…Previously, only one study has reported a lower blood lactate concentration during submaximal cycling when cadence was freely chosen [17]. Here, the type and choice of the NCC seems to be of major importance; theoretically, using different chainring shapes could lead to an optimization of physiological parameters during submaximal exercise [17,23]. Values of VO 2 observed during both endurance tests were much lower than predicted from the incremental stage test, even though blood lactate concentrations were typically higher than those predicted.…”

“…As in leg cycling, no influence of NCC on metabolic submaximal parameters was identified [15,[21][22]. Previously, only one study has reported a lower blood lactate concentration during submaximal cycling when cadence was freely chosen [17]. Here, the type and choice of the NCC seems to be of major importance; theoretically, using different chainring shapes could lead to an optimization of physiological parameters during submaximal exercise [17,23].…”

“…To improve the propulsion technique in cycling, the benefit of noncircular chainrings (NCCs) has been extensively examined since 1977 [12]. Further studies analyzing different types of NCCs concentrated on short-term, submaximal exercise but reported discrepant results [13][14][15][16][17][18][19][20][21][22]. The reasons for such conflicting results in leg cycling could be the varying types of NCCs, test procedures, and characteristics of recruited participants.…”

Effects of chainring design on performance in competitive cyclists

“…On the other hand, Hansen et al, found that there were similar profiles between a noncircular chainring (Biopace) and circular chainring. No significant differences were found between peak torque, min torque, and crank angle at peak torque (10).…”

“…Previous research has shown mixed results between noncircular and circular chainrings (1,3,4,5,9,10,12,13,22,12,13,14,15,22,23,28,38,39,40,42,46). There are several studies that have been published comparing the use of these eccentric chainrings, but to our knowledge there is only one published study by Martinez et al that has looked at the Rotor QRings and their effect on performance and metabolic cost (28).…”