自行車功率計
此條目目前正依照其他维基百科上的内容进行翻译。 (2024年11月30日) |
自行車功率計(cycling power meter)是自行車上量測駕駛者輸出功率的裝置。 大部份的功率計會用应变片來量測力矩,若有角速度的資訊,也可以量測功率[1]。
此技術是在1980年代後期應用在自行車上,也在職業自行車比賽中測試過,當時測試的隊伍是Power Pacer原型(Team Strawberry),選手是格雷格·萊蒙德,使用的設備是SRM。此設備已在1989年起商品化,越來越多人使用功率計進行自行車訓練。
功率計也可以用無線通訊的方式,傳輸資料到自行車電腦、智能手机和智能手表。自行車功率計可以即時回饋給自行車運動員,可以精準分析騎車過程,也是訓練時很好用的工具。
電動自行車裡也會加裝自行車功率計,根據駕駛者的出力調整的電動機的動力。
介面
[编辑]較早期的自行車功率計是使用信號線傳輸功率資訊到自行車電腦,此系統的缺點是自行車上需增加電線,不容易清潔,也需要固定電線的相關機構。
自從2009年起的趨勢是改用無線通訊。自行車功率計常會使用ANT+或是蓝牙低功耗協定,也會和標準自行車電腦結合,顯示駕駛者所產生的功率。
技術分類
[编辑]大部份的自行車功率計用应变片來量測力矩,若再加上角速度的資訊,可以計算功率。 使用应变片的功率計會安裝在中轴、後freehub或牙盘。 有些較新型的功率計不使用应变片,而是用裝在手把上的裝置,利用牛顿运动定律,量測自行車駕駛者受到的反向力(重力、風阻、慣性、滾動阻力) ,再結合速度資訊計算駕駛者的功率輸出。
曲柄或是齒爪
[编辑]安裝在曲柄或齒爪(spider)上的功率計透過应变片量測二個從踏板所施加的力矩。從应变片的形變量以及踏板的踏頻可以計算功率。大部份安裝在曲柄上的功率計只能量測單側踏板的力矩,或是需要第二個感測器才能量測兩側踏板的力矩,而安裝在齒爪上的功率計可以量測兩側踏板的力矩。
這種功率計需要特殊的曲柄或是齒爪,不過相容性較高的產品,比較容易從自行車上拆下,再裝在其他自行車上。
Pedals
[编辑]Pedal-based power meters can be located either in the pedal axle or in the pedal body. This type of cycling power meter measures the cyclist’s force exactly where it is applied, through one or both pedals. Power meters with sensors on both pedals can provide a real dual-sided power measurement, that is power data gathered individually on both legs. This feature is useful to observe and correct penalizing differences in performance between legs.
Power meter pedals are easy to install and swap across bikes.
Bottom bracket
[编辑]Bottom bracket power meters rely on the torsional deflection in the BB shaft. This is done by the shaft having a disc at each end with perforations. These perforations are detected using non-contact photo-electric sensors that detect when torque is applied to the left pedal and then doubled. Data is sent digitally to a handlebar mounted computer unit.
These units are difficult to interchange and require a different bottom bracket unit for each bike.
Freehub
[编辑]A freehub power meter uses the same strain gauges that are present in the crank power meters, but it is located in the rear wheel hub and measures the power at the rear wheel. The power measured by a freehub power meter will be slightly less than the power measured by a crank-based power meter due to power losses in the chain, pedals, and bottom bracket. Because freehub power meters are built into the rear wheel, it is simple to interchange them among bikes so long as the wheels are compatible.
Chain
[编辑]At the heart of Bicycle chain units is essentially a guitar pick-up that mounts to the cycle's chain stay. The pick-up detects chain vibration from which it calculates chain tension which, along with chain speed, gives power output. Finnish company Polar was the first to bring a chain-based power meter to market.
反向力
[编辑]反向力功率計會量測坡度(重力)、自行車加速度(慣性),有時也會量測風速。根據這些資訊間接算出駕駛者輸出的功率。
相關條目
[编辑]參考資料
[编辑]外部連結
[编辑]- cycling shoes
- Book: Training and Racing with a Power Meter, 2nd Ed.
- DC Rainmaker - The Power Meters Buyer’s Guide–2016 Edition
- Anhalt, Tom. What's up with those funky rings...?. January 12, 2013.
- Sullivan, Mark. Bicycle Crank Power Meters and Round and Non-Round Chainrings. October 3, 2014.
- Abbiss, C.; Quod, M.; Levin, G.; Martin, D.; Laursen, P. Accuracy of the Velotron Ergometer and SRM Power Meter. International Journal of Sports Medicine. 2009, 30 (2): 107–112. PMID 19177315. doi:10.1055/s-0028-1103285.
- Cullen, L.; Andrew, K.; Lair, K.; Widger, M.; Timson, B. Efficiency of Trained Cyclists Using Circular and Noncircular Chainrings. International Journal of Sports Medicine. 2008, 13 (3): 264–9. PMID 1601563. doi:10.1055/s-2007-1021264.
- Hopker, J.; Myers, S.; Jobson, S. A.; Bruce, W.; Passfield, L. Validity and Reliability of the Wattbike Cycle Ergometer (PDF). International Journal of Sports Medicine. 2010, 31 (10): 731–6. PMID 20665423. doi:10.1055/s-0030-1261968.
- Driss, Tarak; Vandewalle, Henry. The Measurement of Maximal (Anaerobic) Power Output on a Cycle Ergometer: A Critical Review. BioMed Research International. 2013, 2013: 589361. PMC 3773392 . PMID 24073413. doi:10.1155/2013/589361 .
- Bini, Rodrigo Rico; Dagnese, Frederico. Noncircular chainrings and pedal to crank interface in cycling: a literature review (PDF). Revista Brasileira de Cineantropometria e Desempenho Humano. 2012, 14 (4): 470–82. doi:10.5007/1980-0037.2012v14n4p470 .
- Strutzenberger, Gerda; Wunsch, Tobias; Kroell, Josef; Dastl, Jacqueline; Schwameder, Hermann. Effect of chainring ovality on joint power during cycling at different workloads and cadences. Sports Biomechanics. 2014, 13 (2): 97–108. PMID 25122995. S2CID 812286. doi:10.1080/14763141.2014.908946.
- powerpod depth review