MacRAE, H. S-H., K. J. HISE, and P. J. ALLEN. Effects of front and dual suspension mountain bike systems on uphill cycling performance. Med. Sci. Sports Exerc., Vol. 32, No. 7, pp. 1276-1280, 2000.
Purpose: The purpose of this study was to evaluate the effects of front suspension (FS) and dual suspension (DS) mountain bike designs on time-trial performance and physiological responses during uphill cycling on a paved- and off-road course.
Methods: Six trained male cyclists (35.6 ± 9 yr, 76.9 ± 8.8 kg, V̇O2peak 58.4 ± 5.6 mL·kg-1·min-1) were timed using both suspension systems on an uphill paved course (1.62 km, 183-m elevation gain) and an uphill off-road course (1.38 km, 123-m elevation gain). During the field trials, V̇O2 was monitored continuously with a KB1-C portable gas analyzer, and power output with an SRM training system.
Results: On the paved course, total ride time on FS (10.4 ± 0.7 min) and DS (10.4 ± 0.8 min) was not different (P > 0.05). Similarly, total ride time on the off-road course was not significantly different on the FS bike (8.3 ± 0.7 min) versus the DS bike (8.4 ± 1.1 min). For each of the course conditions, there was no significant difference between FS and DS in average minute-by-minute V̇O2, whether expressed in absolute (ABS; L·min-1) or relative (REL; mL·[kg body wt + kg bike wt-1]·min-1 values. Average power output (W) was significantly lower for ABS FS versus DS (266.1 ± 61.6 W vs 341.9 ± 61.1 W, P < 0.001) and REL FS versus DS (2.90 ± 0.55 W·kg-1 vs 3.65 ± 0.53 W·kg-1, P < 0.001) during the off-road trials. Power output on the paved course was also significantly different for ABS FS versus DS (266.6 ± 52 W vs 345.4 ± 53.4 W, P < 0.001) and REL FS versus DS (2.99 ± 0.55 W·kg-1 vs 3.84 ± 0.54 W·kg-1, P < 0.001).
Conclusion: We conclude that despite significant differences in power output between FS and DS mountain bike systems during uphill cycling, these differences do not translate into significant differences in oxygen cost or time to complete either a paved- or off-road course.
Despite significant advances in mountain bike suspension systems in recent years, little is known about the effects of these systems on rider performance. Furthermore, the effects of these suspension systems on rider performance under field conditions have, to our knowledge, only received limited investigation (2,9).
The majority of mountain bikes produced at present are equipped with either a front suspension (FS) or a front and rear (dual) suspension (DS) system, the latter purported to increase rider comfort, control, and possibly performance, perhaps by reducing physical trauma due to excessive vibration. Although the benefits of a DS design may seem obvious, the potential disadvantages from the standpoint of metabolic cost to the rider have not been fully examined. The loss of pedaling energy due to compression of the suspension system followed by spring dampening has the potential to result in greater energy expenditure compared with a front-only suspension system.
In a competitive cycling setting, rider performance is best determined by time to completion of a set course. Although this is the final and most direct measurement of a cyclist's athletic ability, other parameters such as oxygen consumption and power output can also be utilized to assess differences in bike design, all else being equal. One recent study reported no difference in energy expenditure between cyclists riding front and dual suspension equipped bicycles (9).
Due to the fact that approximately 70% or more of race time on North American mountain bike cross-country courses is spent climbing (U.S. Cycling, personal communication), we were particularly interested in determining the metabolic and physiological responses during uphill mountain-bike cycling. Thus, the objective of this study was to assess the effects of FS versus DS systems on oxygen consumption, power output, and other physiological variables during uphill cycling on a paved- and off-road course.