Bike Fit and Mechanical Efficiency Testing
Efficiency and Bike fit
The Exercise Institute is now able to provide bike fitting aimed at improving comfort and performance in measurable terms. What this means for the individual is twofold; one, we are able to refine your position until a comfortable position is found; two, we are able to measure your oxygen consumption in real time to assess if the changes are improving your power output per oxygen consumption. We are the first in WA, and possibly Australia, to be able to provide this combined service.
This brings objective measurement to a subjective assessment. By measuring the liters of oxygen consumed per watt produced at the rear wheel we are able to outline what position IS more efficient.
Importantly we can offer follow up refinement of your cycling position, post bike fitting, every time you train at the center meaning the process of legitimate fitting can occur over time, and be refined as you adjust to the new position. Please contact us today firstname.lastname@example.org
Some more detailed information is provided for your reference below:
The major physiologic determinants for road cycling performance are the VO2 max, the ventilatory thresholds and mechanical efficiency (Jacobs et al., 2011).
Gross efficiency is defined as the energy expended for a given work load, i.e. how many kilojoules of energy your body needs to consume in order to achieve a certain wattage (Sidossis, Horowitz, & Coyle, 1992). Typically efficiency will range between 10% and 25% (Donovan & Brooks, 1977). At a certain speed requiring 300 watts, 18kj is expended over 1 minute (assuming 100% efficiency). Therefore, to achieve 25% efficiency, the body will need to expend 72kj.
Expending less energy for a given work load is associated with performance improvement because lower respiratory ratios are seen. A lower respiratory ratio means less fatiguing agents are released, such as lactic acid, and, that fats are used, sparing the body’s limited source of carbohydrates for higher intensity work (Bellar & Judge, 2012).
Small changes in efficiency can have a large effect on performance, for example an improvement in efficiency by 1% will reduce a 40km time trial time by 1 minute (Moseley & Jeukendrup, 2001).
There are a number of ways to improve efficiency, for example, high intensity training (Hopker, Coleman, Passfield, & Wiles, 2010), strength training (Paton & Hopkins, 2005), improving the running gear used in the drive chain, and from alterations in biomechanics from a bike fit (Grappe, Candau, Busso, & Rouillon, 1998).
Very large changes in efficiency can be seen with bike fit adjustments. For example changing the torso angle of the back from 22 degrees to 2 degrees (flat back) can reduce efficiency significantly (Grappe et al., 1998). Though this is the case, reducing the torso angle can also significantly reduce aerodynamic drag (Grappe, Candau, Belli, & Rouillon, 1997), so a trade-off between the two variables is needed to optimize performance.
At The Exercise Institute, we can do metabolic efficiency testing and inferential aerodynamic drag testing concurrently in different bike fit positions to optimise performance for the individual. Conversely, we can also adjust the bike fit position to optimize these variables based on data from research. Whilst this method is much quicker, it is not as accurate as the dual testing method, however it is still a valid estimate.
Bike Fit & detailed report: $180
Bike Fit & Efficiency Testing & detailed report: $380
Bellar, D., & Judge, L. W. (2012). MODELING AND RELATIONSHIP OF RESPIRATORY EXCHANGE RATIO TO ATHLETIC PERFORMANCE. Journal of Strength and Conditioning Research, 26(9), 2484-2489. doi: 10.1519/JSC.0b013e31823f271d
Donovan, C. M., & Brooks, G. A. (1977). MUSCULAR EFFICIENCY DURING STEADY-RATE EXERCISE .2. EFFECTS OF WALKING SPEED AND WORK RATE. Journal of Applied Physiology, 43(3), 431-439.
Grappe, F., Candau, R., Belli, A., & Rouillon, J. D. (1997). Aerodynamic drag in field cycling with special reference to the Obree’s position. Ergonomics, 40(12), 1299-1311. doi: 10.1080/001401397187388
Grappe, F., Candau, R., Busso, T., & Rouillon, J. D. (1998). Effect of cycling position on ventilatory and metabolic variables. International Journal of Sports Medicine, 19(5), 336-341. doi: 10.1055/s-2007-971927
Hopker, J., Coleman, D., Passfield, L., & Wiles, J. (2010). The effect of training volume and intensity on competitive cyclists’ efficiency. Applied Physiology Nutrition and Metabolism-Physiologie Appliquee Nutrition Et Metabolisme, 35(1), 17-22. doi: 10.1139/h09-124
Jacobs, R. A., Rasmussen, P., Siebenmann, C., Diaz, V., Gassmann, M., Pesta, D., . . . Lundby, C. (2011). Determinants of time trial performance and maximal incremental exercise in highly trained endurance athletes. Journal of Applied Physiology, 111(5), 1422-1430. doi: 10.1152/japplphysiol.00625.2011
Moseley, L., & Jeukendrup, A. E. (2001). The reliability of cycling efficiency. Medicine and Science in Sports and Exercise, 33(4), 621-627.
Paton, C. D., & Hopkins, W. G. (2005). Combining explosive and high-resistance training improves performance in competitive cyclists. Journal of Strength and Conditioning Research, 19(4), 826-830.
Sidossis, L. S., Horowitz, J. F., & Coyle, E. F. (1992). LOAD AND VELOCITY OF CONTRACTION INFLUENCE GROSS AND DELTA-MECHANICAL EFFICIENCY. International Journal of Sports Medicine, 13(5), 407-411. doi: 10.1055/s-2007-1021289