Cycling performance and mechanical variables using a new prototype chainring

Abstract

The primary aim of our study was to examine supra-maximal cycling performance and related mechanical variables in trained cyclists using a new prototype chainring (PC) designed to produce a higher mean net torque (T (N mean)) than a standard chainring (SC). The main feature of the PC is that crank-arm alignment and lever-arm length change as a function of the crank angle during the pedaling cycle. The PC presents two features theorized to effect cycling performance: (1) out of line of pedal cranks resulting in an decrease in the dead points, and (2) a change in crank arm length inducing a torque different from that of SC during the down- and up-stroke of the pedaling cycle. To investigate this theory, we examined eight male cyclists who performed a 1-km "all-out" cycling test in the following order: SC, PC, and SC. Performance was measured as the time (s) to complete the 1-km test. Mechanical variables included torque (N m(-1)), crank velocity (rad s(-1)), and power output (W). We performed our statistical analysis using a two-way ANOVA for repeated measurements and Newman-Keuls post hoc assessment. Our results showed that performance was similar for SC (69.41 +/- 6.69 s) and PC (73.33 +/- 4.58 s). Torque, crank velocity, and power output were also similar throughout (P > 0.05). We conclude that despite the theoretically benefits proposed by the inventors the new PC investigated in our study failed to improve cycling performance or mechanical variables during a supramaximal test when compared with SC.

Influence of noncircular chainring on male physiological parameters in hand cycling

“…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.…”

Sistemas de pedivela não-circulares e interfaces pedal-pedivela no ciclismo: uma revisão da literatura.

“…With this in mind, changes in crank length 8,9 , pedal to crank interface 10,11 , and in the regular profile of the chainring have been devised (Figure 1) [12][13][14] . Even with strong theoretical support, some of these novel devices uncertainly affect biomechanical, physiological or performance variables [15][16][17][18] . Different designs of noncircular chainrings and pedal to crank interfaces have been presented in the literature and have affected physiological and biomechanical variables related to performance in different ways.…”

Effects of chainring design on performance in competitive cyclists

“…Contrary to the previously discussed studies, there were no significant differences in power using an eccentric chainring design in several other studies (3,15). Jobson also found no increases in power or cycling performance using an eccentric crank system after six weeks of training, but does suggest that the system could have acute ergogenic effects if used infrequently (18).…”

“…Of particular interest is the design of noncircular chainrings in replacement of the traditional circular chainrings on bicycles. Since the late 1890's there have been many attempts to increase the efficiency of pedaling and reduce the effects of the dead centers (2,3,12,23,45).…”

“…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).…”