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自行車的金屬輻條
輻條是从車輪中心的轮毂（即与轴相连的地方）辐射出来的杆、条等，它把轮毂和圆形的轮圈连接起来。
历史[ | ]
辐条轮的出现使车辆更加轻便。辐条最早出现在公元前2000年的安德罗诺沃文化中。不久之后，高加索地区的游牧民族就使用了装有辐条轮的马战车，持续将近三个世纪。他们随后开始迁移，深入希腊半岛，与当地的地中海民族汇合，在米诺斯文明消亡之后建立了古典希腊（后被斯巴达吞并）。凯尔特人则在公元前几百年就在战车车轮外加上了铁圈。这种辐条轮一直沿用至1870年代，这时钢丝轮和橡胶轮胎问世了。[1]
类型[ | ]
辐条的材质可以是木头、金属、合成纤维等，这取决于辐条是受拉还是受压。
压缩辐条[ | ]
木质辐条轮最早用于马车和马拉的货车。早期的机动车用的通常是装在炮架上的木质辐条轮。
简易的木质轮轮毂受压时，轮圈靠近地面的地方会略有凹陷，最低的一根木质辐条因受压而变短，而其他的辐条则没有明显变化。
木质辐条常沿半径方向安装，同时呈向外的碟形，以避免车辆摇晃。通过增加碟形的程度还能抵消辐条因受潮而产生的膨胀。[2]
张力辐条[ | ]
自行车的车轮不是笨重的木质辐条轮，而是钢丝轮。这种车轮更加轻便，它的辐条是拉紧但可调节的金属丝。轮椅、摩托车、汽车也用这种车轮。
类型[ | ]
有些车轮的辐条可以一根根取下，若有弯曲或折断便能更换。自行车和轮椅车轮的辐条就是这样。质量高的自行车所配的常规车轮用的是不锈钢辐条，而比较便宜的自行车用的是镀锌或镀铬的辐条。高质量的辐条可承受225千克力，不过实际使用时负载只有它的几分之一以避免疲劳损坏。因为自行车和轮椅的辐条只会处于拉伸状态，其材质也可以是柔韧性强的材料（如合成纤维）。[3]
对负载的反应[ | ]
当编得很好的钢丝辐条轮承受径向负载（如车手坐在自行车上）时，车轮与地面接触处附近会略有凹陷，其余部分则基本保持圆形。[4][5][6][7] 所有辐条的张力都没有显著增加，轮毂正下方的辐条张力还有所降低。[8][9][10][11] 对如何描述这种情形存在争议。[12] 有人认为轮毂“站”在正下方那根张力减小的辐条上，[6][8] 还有人认为轮毂“挂”在正上方那根张力较大的辐条上。[10][13]
虽然钢丝轮的辐条又细又柔韧，但沿半径方向却是刚性的，所以辐条的悬挂随动与高压自行车轮胎相比都不值一提。 [14][15][16][17]
参考文献[ | ]
- ↑ Herlihy, David. Bicycle: the History. Yale University Press. 2004: 141 [2009-09-29]. Template:Citation/identifier.
- ↑ Hansen Wheel and Wagon Shop [2006-08-22]（原始内容存档於2006-08-14）.
- ↑ PBO Spoke Technology [2011-10-21].
- ↑ Forester, John. Held Up By Downward Pull. American Wheelmen. August 1980.
- ↑ Whitt, Frank R.; David G. Wilson. Bicycling Science. Second. Massachusetts Institute of Technology. 1982: 106–138. Template:Citation/identifier.
- ↑ 6.0 6.1 Ian Smith. Bicycle Wheel Analysis [2008-12-31]. "I conclude that it is perfectly reasonable to say that the hub stands on the lower spokes, and that it does not hang from the upper spokes."
- ↑ C.J. Burgoyne and R. Dilmaghanian. Bicycle Wheel as Prestressed Structure (pdf). Journal of Engineering Mechanics. March 1993, 119 (3): 439–455. ISSN 0733-9399. doi:10.1061/(asce)0733-9399(1993)119:3(439).
Only the spokes in contact with the ground, or near the ground, show significant strains.
- ↑ 8.0 8.1 Brandt, Jobst. The Bicycle Wheel. Avocet. 1981: 12–20. Template:Citation/identifier.
- ↑ Wilson, David Gordon; Jim Papadopoulos. Bicycling Science. Third. Massachusetts Institute of Technology. 2004: 389–390. Template:Citation/identifier.
- ↑ 10.0 10.1 Tom Fine. Hubs hang from the rim!. September 1998 [2010-03-16]. "I still say, without any doubt, that the hub hangs from the upper spokes."
- ↑ Henri P. Gavin. Bicycle Wheel Spoke Patterns and Spoke Fatigue (pdf). ASCE Journal of Engineering Mechanics. August 1996, 122 (8): 736–742. doi:10.1061/(ASCE)0733-9399(1996)122:8(736).
- ↑ Kraig Willett. Hang or Stand?. BikeTech Review. 5 September 2004 [2010-03-16]. "A little known semantic debate ... has been raging on the usenet newsgroups for quite some time. The point of contention in this debate is whether or not a loaded bicycle wheel "stands" on the bottom spokes or "hangs" from the top ones?"
- ↑ Samuel K. Clark, V. E. Gough. Mechanics of Pneumatic Tires. U.S. Department of Transportation. 1981: 241. "The system of load transmission is analogous to that of a cycle wheel where the hub hangs by the steel wire spokes from the top of the rim, which is loaded at the bottom."
- ↑ John Swanson. Performance of the Bicycle Wheel, A Method for Analysis. BikePhysics.com. 2006 [2012-06-25]. "Radial Stiffness: There's almost -no- vertical compliance in your wheel and people who insist that they can feel the vertical stiffness or “harshness” of a wheel are mistaken. The radial stiffness of a bicycle wheel is ~ 3-4000 N/mm. This equals a deflection of 0.1 mm under a 40 kg load. Sorry princess, but that gets obscured by the amount of deflection in the tires, fork, saddle, handlebar tape, frame, and even your gloves."
- ↑ Henri P. Gavin. Bicycle Wheel Spoke Patterns and Spoke Fatigue. ASCE Journal of Engineering Mechanics. 1996 [2012-06-25]. "radial wheel stiffness (N/mm): 2500-5000"
- ↑ Ian. Spoke Patterns. astounding.org.uk. 2002 [2012-06-25]. "A radially spoked wheel is about 4.6% stiffer than a tangentially spoked one. Alternatively, if you apply 1000N (about 100kg, 220lb) to each of the wheels, the tangential (four-cross) spoked one deflects 0.0075mm (0.0003 inch) more than the radial spoked. Since the tyre is likely to deflect several millimetres at least (if 3mm, that's 400 times more deflection) I conclude the spoking is unlikely to make a discernible difference to the vertical stiffness of the wheel."
- ↑ Jobst Brandt. Sheldon Brown's Bicycle Glossary: Radial spoking. Sheldon Brown (bicycle mechanic). 1981 [2012-06-25]. "There is no change in radial elasticity between a radial and crossed spoke wheel with the same components, other than the length of the spokes. A 290 mm spoke is 3% stiffer than a 300 mm spoke of the same type. Since spokes stretch elastically about 0.1mm on a hard bump (not ordinary road ripples), the elastic difference between the radial and cross-three wheel is 3% x 0.1mm = 0.003 mm. Copier paper is 0.075 mm thick, and if you can feel that when you ride over it on a glassy smooth concrete surface, please let me know. You have greater sensitivity than the lady in "the princess and the pea" fable."
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