Equivalent Speed: A New Metric For Cycling Performance...2021 ACSM Annual Meeting & World Congresses [Virtual], June 1 -5, 2021
While Velocita Ascensionale Media (VAM) can predict performance on steep hills, no such metric for flat terrain exists. Cyclists instead rely on power meters and estimates of air density, drag-area (CDA), and coefficient of rolling resistance Crr to predict ideal speed (IS): the speed they can maint...
| Publicado en: | Medicine & Science in Sports & Exercise Vol. 53; no. 8S; p. 29 |
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| Autor principal: | |
| Formato: | abstract proceedings research Journal Article |
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Lippincott Williams & Wilkins
2021 Supplement
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| Acceso en línea: | Ver este registro en EBSCOhost |
| fields | @attributes: recordID: 1 pdfLink: plink: https://search.ebscohost.com/login.aspx?direct=true&db=ccm&AN=152581545&site=ehost-live header: @attributes: shortDbName: ccm uiTerm: 152581545 longDbName: CINAHL Complete uiTag: AN controlInfo: bkinfo: dissinfo: jinfo: jid: 01959131 4DP jtl: Medicine & Science in Sports & Exercise issn: 01959131 maglogo: N pubinfo: dt: 2021 Supplement vid: 53 iid: 8S pid: 433 pub: Lippincott Williams & Wilkins place: Baltimore, Maryland artinfo: ui: 152581545 152581545 152581545 10.1249/01.mss.0000759392.75434.98 152581545 ppf: 29 ppct: 0 formats: tig: atl: Equivalent Speed: A New Metric For Cycling Performance...2021 ACSM Annual Meeting & World Congresses [Virtual], June 1 -5, 2021 aug: au: Bollt, Scott A. affil: California Institute of Technology, Pasadena, CA sug: subj: Athletic Performance Cycling Exercise Intensity Validity Clinical Assessment Tools Congresses and Conferences ab: While Velocita Ascensionale Media (VAM) can predict performance on steep hills, no such metric for flat terrain exists. Cyclists instead rely on power meters and estimates of air density, drag-area (CDA), and coefficient of rolling resistance Crr to predict ideal speed (IS): the speed they can maintain on a flat windless road. We propose a new parameter-free metric, Equivalent Speed (ES), to predict IS given just speed data. Unlike average speed, V, ES (the distance-weighted average of speed, ν) approximates IS closely. ES assumes constant CDA on a closed loop course. Average drag is proportional to ν², so on a closed course in the absence of wind or braking and ignoring the constant energy lost to rolling resistance, power is given roughly by P∝ν2V. An approximation to third order changes in speed about ES is P∝ν³. Since IS is defined to be constant, VIS=νIS and we find in this case PIS∝VIS 3. ES is then the solution to P=PIS for VIS. PURPOSE: To test the accuracy of ES in different conditions. METHODS: A standing start, out-and-back 40km time trial with 4 total sinusoidal hills is simulated. The following parameters are used. Frame mass: 7kg, wheel mass: 2kg, Crr: 0.0035, CDA: 0.25m², air density: 1.225 kg/m³, braking force: 200N. Hills of 0% (flat), 2%, 5%, and 10% gradient are tested. Both direct headwinds and crosswinds of 0m/s, 2m/s, 4m/s and 6m/s are tested on the flat course. Rider mass is 50kg, 75kg, or 100kg on the 2% course, but 75kg in the other tests. Rider power is 200w, 300w, or 400w on the 2% course, but 300w in the other tests. RESULTS: On the flat course the standing start and turnaround portions cause ES to incur an error (IS-ES)/IS=0.43%, where IS=12.17m/s. This error is mostly due to the start and turnaround (1.28% energy loss). ES incurs errors of 0.32%, 0.40%, and 0.42% for the 50kg, 75kg, and 100kg riders, with errors of 0.21% and 0.46% at 200w and 400w. ES incurs errors of -0.88% and - 7.1% on the 5% and 10% climbs. Speeds of twice IS are achieved on the 10% descent: too large for the third order approximation. Errors of 0.18%, -0.59% and -1.9% result from 2m/s, 4m/s, and 6m/s headwinds, with errors of 0.86%, 2.1%, and 4.0% in the respective crosswinds. CONCLUSIONS: Without a power meter or flat roads, ES can predict IS using just speed data. Error is less than 1% except on descents steeper than 5%, or in headwinds over 4m/s, or crosswinds over 2m/s. pubtype: Academic Journal doctype: abstract proceedings research Journal Article ougenre: Article language: English refInfo: holdings: @attributes: islocal: N |
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