自由車的發展可以追溯到19世紀末期，隨著科技的進步和創新，現代自由車包括公路賽車、山地賽車、場地賽車等多個領域，競賽的強度隨著時間的推移而改變，訓練方法和科學技術的進步也提高了選手的表現和比賽強度。
風洞實驗是研究自由車空氣動力學的重要方法之一。通過在風洞中模擬真實的騎行條件，研究人員可以測量選手和自由車系統的阻力係數(Coefficient of Drag, CD)以及阻力面積(Coefficient of Drag Area, CDA)。除了風洞實驗方法，還可以使用功率計算方法來估計選手和自由車系統的CDA。功率計用於測量騎行過程中產生的功率，通過測量選手的功率輸出、騎乘速度、風速等參數，使用數學模型計算出CDA。路騎實驗除了能直接在競賽場地進行實驗，更有便利性高、數據擷取方便等優勢。而為確保路騎實驗參數的取得及準確度，曲柄功率計及三孔風速計微流體感測實驗室自行開發的量測儀器。
因此本研究總共包含三次實驗，兩次路騎實驗實驗A、B與一次風洞實驗實驗C，風洞所設定之雷諾數範圍為2.5×105~11×105，對應選手於自由車競賽騎乘與衝刺之速度(32~90 km/hr)，每次實驗當中都會量測風速、溫度與阻力；路騎實驗則透過車錶取得絕對速度、路面坡度；曲柄功率計與踏板功率計取得功率以及三孔風速計測得風速和風向角。
在路騎實驗A中發現功率與騎乘速度之存在著0至6秒不等的時間差，意即當選手在騎乘當中若有加速的動作，功率會先上升，接著人與車的整個系統速度才會跟著上升；另外，相對風速Urel的擾動主要來自於周圍風場，數值的高低則為騎乘速度主導。也因此可推斷當騎乘速度越快時Vhw向量占比下降，側風的影響將會降低，風向角的標準差下降，因此越接近風洞的實驗條件。 在路騎實驗B中發現自製的曲柄功率計數值皆較市售的踏板功率計高出3~20%不等，而作用於曲柄和踏板的力量相位差則為造成兩種功率計的數值差異的最大來源。在一圈的踩踏當中並不是等轉速運動，而是有波峰和波谷的存在，因此當兩種形式的功率計量測到的力矩存在相位差的話，即會造成量測數值的差異。而在兩次路騎實驗計算條件設置完全相同的情況下，兩件車衣的差異比較下則都是車衣 B 優於車衣A，且都是有大約10%的差異，結果一致。
在風洞實驗中車衣B於高寬比越小的選手身上能有越好的效果，因此男選手A2021年至2023年高寬比自1.52下降至1.41，使車衣B於他身上的效果變佳。與路騎實驗的驗證可以發現在計算條件完全相同的情況下，踏板功率計所得出的 CDA 數值都較低，源自於功率值本身就低於曲柄功率計；曲柄功率計所得出的 CDA 則較接近風洞量測值；另外，可以透過功率計算方式看出不同車衣於同一位選手的差異，而使用不同形式的功率計雖然計算出的 CDA 數值不同，但會有大致相同的優劣趨勢。

Wind tunnel testing is an important method for studying the aerodynamics of cycling. By simulating real riding conditions in a wind tunnel, researchers can measure the coefficient of drag (CD) and the coefficient of drag area (CDA). In addition to wind tunnel experiments, the power calculation method can also be used to estimate the CDA of the cyclist. By measuring parameters such as the cyclist's power output, riding speed, and wind speed, researchers can calculate the CDA using mathematical models. Road testing experiments have advantages such as high convenience and easy data collection. The results show that with riding speed increasing, the Vhw vector decreases, the influence of crosswind decreases, resulting in experimental conditions closer to those of the wind tunnel. The CDA values obtained from the crank power meter were closer to the values measured in the wind tunnel. Furthermore, by using the power calculation method, the differences between different jerseys for the same athlete can be observed.
Keywords: Bicycle, wind tunnel experiment, road Test, power measurement and calculation

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