In a paceline, the all-road bike performed like a great racing bike. On gravel roads, it worked as well as a good mountain bike. On twisty descents, it outshone any other bike, since its wider tires offered more grip and better suspension.
Tires 轮胎
“I was prepared for some improvement, but the magnitude surprised me. Obviously, the new tires rolled faster, but more than that, they changed the character of the bike.”
我对换胎带来的提升做好了心理准备，但这提升的幅度还是惊讶到了我。显然，这条新胎滚动地更快了，但更重要的是，它改变了这辆车的性格。
Tires are the easiest and most effective performance upgrade for your bike. When getting a new bike, your first consideration should be the tires you want to use (see p. 13). Everything else will follow from that. In this chapter, we’ll look at what determines the performance of your tires.
轮胎是你自行车上最容易也是最有效的升级选项。当你买新车时，首先应该考虑的是你想用什么样的胎（见第13页），其他一切都该在选完胎后再做决定。在本章中，我们将看看是什么决定了轮胎的性能。
Pneumatic tires were the most important technological step forward in the entire history of the bicycle. Until the 1890s, cycling struggled to catch on because solid rubber tires gave a bone-shaking ride. Even hollow tires, still without pressurized air, did little to improve matters.
Pneumatic tires changed all that - not only were they more comfortable, but also much, much faster. However, pneumatic tires also introduced the bane of cyclists’ existence: flat tires. In the 1890s, changing a tire required removing the side of the rim with dozens of screws. Most cyclists dealt with a puncture by walking to the next train station and taking the train home, where they could disassemble the wheel, fix the tire, and reassemble it.
充气轮胎是整个自行车历史中最重要的一个技术进步。由于实心橡胶胎骑行时颠簸得厉害，到19世纪90年代为止，骑自行车都一直难以流行起来。即使是空心橡胶胎，对改善这一状况也几乎没有帮助，因为里面没有压缩空气作为减震。
充气轮胎改变了这一切——它们不仅更舒适，而且速度也快得多。然而，充气轮胎也给骑手们带来了诅咒：爆胎。在19世纪90年代，更换轮胎需要卸下轮圈的一侧，这要拆装几十个螺丝。大多数骑车人在遇到扎胎时，会选择步行到下一个火车站，然后乘火车回家，在家里拆开轮子，修理轮胎，再重新组装起来。
When pneumatic tires became available, the cycling world split into two groups: long-distance tourists and scorchers. The former prized their self-reliance, so they stuck with airless tires and rode slowly and deliberately. The scorchers, on the other hand, rode fast on their pneumatic tires, but never strayed far from home for fear of getting stranded.
Tire technology soon improved. Once punctures could be fixed on the road, cyclotourists also adopted pneumatic tires. They saw their reach vastly increased and their enjoyment multiplied. Combining the speed of the scorchers with the long-distance adventures of cyclotouring gave birth to a new sport - randonneuring - and new bikes that were the ancestors of today’s all-road bikes.
当充气轮胎出现时，自行车手们分成了两派：长途骑行者和飙车党。前者重视自力更生，因此他们坚持使用实心轮胎，往心中的目的地缓慢又坚定地踩着踏板。而飙车党们则在他们的充气轮胎上竞速，但由于担心被困在路上，他们从不远离家门太远。
轮胎技术很快得到了改进。一旦可以在路上修补爆胎，长途骑行者也开始接纳充气轮胎。他们发现自己的活动范围大大增加，乐趣也成倍增长。将飙车党的速度与长途骑行的冒险结合在一起，催生了一项新的运动——randonneuring——以及新类型的自行车。这种自行车就是今天全地形自行车的前身。
注：randonneuring暂时没有官方的中文译名。这是一种长距离无支援的耐力自行车运动，其本质上是非竞争性的，所强调的乃是骑行过程中的自给自足。国内著名的八天川藏挑战就可以算是一种randonneuring。
Over the next century, the joyful revolution of riding on a cushion of air was forgotten, and cycling (almost) returned to the harsh old days. Racers adopted narrower and narrower tires, pumped to higher and higher pressures, until their bikes (almost) emulated the boneshakers of old. Many touring cyclists, trying to avoid flat tires at all costs, adopted puncture-resistant tires with belts and foam layers under the tread that stopped even thumb tacks from penetrating the air filled inner tube. These tires were so stiff that they resembled the ‘hollow rubber’ of the old days, and they robbed tire and bike of much of their liveliness.
Recently, these trends have been reversed. Racers are moving to wider and wider tires, and running them at lower pressures - not only on the cobblestones of Paris-Roubaix, but even on the smooth roads of the Tour de France. Riders have found that by adopting wider tires, the risk of flats is much reduced, and even casual riders can enjoy supple high-performance tires without worry. Once again, cyclists enjoy the speed of scorchers and the independence of tourists.
在接下来的一个世纪里，骑在气垫上这种革命性的快乐仿佛被遗忘了，骑行（几乎）回到了那些艰苦的旧日时光。赛车手们使用越来越窄的轮胎，将它们充到越来越高的气压，直到他们的自行车（几乎）骑起来就像自行车刚被发明时颠到人骨头疼的boneshakers。许多长途骑行者为了尽量避免爆胎，采用了胎面下具有保护带和泡沫层的防刺轮胎，这些设计甚至可以阻止图钉穿透充满空气的内胎。然而，这种轮胎非常的僵硬，让人想起了过去的“空心橡胶胎”，装上它们简直剥夺了自行车的生机和活力。
最近，这些趋势已经发生了逆转。比赛中的车手们正在转向越来越宽的轮胎，并且开始使用更低的气压——不仅是在巴黎-鲁贝的鹅卵石路上，甚至在环法自行车赛的平滑路面上也是如此。骑手们发现，采用更宽的轮胎将大大降低爆胎的风险，即使是休闲骑手也可以毫无顾虑地享受柔软的高性能轮胎。峰回路转，骑手们又一次享受到了竞速的乐趣和自给自足的长途骑行。
How important are tires? Imagine going at moderate speeds of about 15 mph (25 km/h) on a popular tire model. Change your tire for the fastest model we have tested, and you immediately go 18 mph (29 km/h). That is 17% faster, with the same power output. It’s hard to believe, yet it’s been confirmed in numerous tests. At higher speeds, you will still see a speed difference of 8% or more. (Compare that to aero wheels, which give you a speed advantage of about 1-2% at high speeds.)
In a peloton, wind resistance is greatly reduced, and your tires are the main resistance you have to overcome. The advantage of faster tires is greatly magnified, allowing riders on faster tires to get more rest between pulls at the front.
轮胎有多重要？想象一下用一款流行的入门胎以大约15英里/小时（25公里/小时）的中等速度骑行（译者注：可以代入马牌ultra sport），如果更换成我们测试过的最快的高性能胎，速度会立刻提升到18英里/小时（29公里/小时）。这意味着，在同样的功率输出下，速度提高了17%。这听起来难以置信，但已经在多次测试中得到了证实。在更高的速度下，你仍然可以看到至少8%的速度差异。（相比之下，空气动力学轮组在高速时只能给你带来大约1-2%的速度优势。）
在集团中，风阻被大大减小，这时你的轮胎滚阻就成为你需要克服的主要阻力。更快的轮胎所带来的优势会被显著放大，让使用更快的轮胎的车手在集团前方领骑后能够得到更多的休息。
What Makes a Tire Fast? 什么让轮胎更快？
For Bicycle Quarterly’s tire tests, we evaluated the performance of more than 35 different tire models, both in roll-down tests and with a power meter. Rather than a simple ranking of tire brands and models, our goal was to determine what makes a tire fast.
Our research confirmed what professional racers have known for decades: To make a fast tire, you need a supple casing. Everything else is secondary: width, tread compound, etc. The five fastest tires in our testing ranged in width between 24.5 and 49 mm. They included tubulars and clinchers. The common trait was that they all used extra-supple casings.
在《自行车季刊》的轮胎测试中，我们评估了超过35种不同轮胎型号的表现，既进行了不踩踏的滚动测试（roll-down test）也进行了有踩踏的功率计测试。我们的目标不是简单地对轮胎品牌和型号进行排名，而是要确定是什么让一款轮胎变得快速。
我们的研究证实了专业车手已经知道了几十年的事实：要造出一个高性能的快速轮胎，你需要一个柔软的胎体。其他因素都是次要的，如宽度、胎面材料等等。在我们的测试中，最快的五款轮胎宽度介于24.5毫米到49毫米之间。它们包括管胎和开口胎，而共同的特点是：它们都采用了特别柔软的胎体。
Supple Casing 柔软的胎体
A supple casing is the defining feature that differentiates a fast-rolling, comfortable high-performance tire from a slow and harsh-riding utility tire. What makes a casing supple?
Casings are made of threads. The finer the threads, the more supple the casing. Coarse threads are much stiffer, and take more energy to flex. The threads of a utility tire are more than twice as thick as those of a high-performance tire. With oversize frames, increasing the tube diameter by 12% changes the feel of the bike - imagine what happens if you double the diameter of the threads in your tire casing!
柔软的胎体是区分滚动轻快、骑感舒适的高性能轮胎与滚动迟缓、骑感颠簸的普通轮胎的关键特征。是什么让胎体变得柔软呢？
胎体是由帘线构成的。帘线越细，胎体就越柔软。而粗帘线要硬得多，并且形变时需要消耗更多的能量。普通轮胎的帘线比高性能轮胎的帘线粗两倍多。对于超大尺寸的车架来说，将车架管材的直径增加 12% 就会改变自行车的骑行感觉 —— 想象一下，要是把轮胎胎体中帘线的直径增大一倍，会出现什么情况！
The actual material of the threads also plays a role. Traditionally, silk tubulars were prized over cotton ones, because silk is more supple. Today, only a few handmade tubular tires still use silk casings. Cotton tires still exist, but polyester is the most common thread material, and it can offer excellent performance as well. Within each material, there are different grades, and it is difficult to generalize which material is superior.
A finer thread means that more threads are used, and so ‘threads per inch’ (TPI) has become a shorthand for casing suppleness. This is only partially correct. Finer threads do result in more threads per inch of casing fabric, so the TPI increases. However, if you cram as many threads as possible into each inch - thus getting the highest TPI - you create an ultra-dense weave that makes the casing stronger, but also less supple. The fastest tires use the finest threads, but in a slightly looser weave that makes them even more supple (and coincidentally decreases their TPI). The looser weave also decreases the tire’s strength, so there is a limit beyond which the cut resistance of the casing is no longer adequate.
帘线的实际材质也很重要。传统上，丝绸管胎比棉质的管胎更受青睐，因为丝绸更柔软。如今，只有少数手工制作的管胎仍使用丝绸胎体。棉质轮胎依然存在，但聚酯是最常见的帘线材料，它也能提供出色的性能。每种材质都有不同的等级，很难一概而论地说哪种材质更优越。
更细的帘线意味着在相同面积下使用的帘线数量会更多，因此 “每英寸帘线数”（TPI）已成为衡量胎体柔软度的简便指标。但TPI并不完全准确。更细的帘线确实会使每英寸胎体织物中的帘线数量增多，从而提高 TPI 值。然而，如果你在每英寸内尽可能多地塞进帘线，从而获得最高的 TPI 值，就会形成一种超紧密的编织结构，这会使胎体更坚固，但也会降低其柔软度。最快的轮胎使用最细的帘线，但编织方式稍显疏松，这让它们更加柔软（巧合的是，TPI 值也会降低）。较疏松的编织结构也会降低轮胎的强度，所以当超过一定限度时，胎体的抗切割能力就会不足。
Some companies advertise improbably high TPI of 150 or more. Threads that fine are too fragile to make bicycle tires - these companies count each layer of the three casing layers, so their 300 TPI tires are the equivalent of what most manufacturers count as a 100 TPI casing.
Finer threads are more fragile and have to be handled with greater care during the manufacturing process. Factories that usually make budget tires are poorly equipped to handle such delicate casings, so they coat them in thick rubber to make the casing more resistant to damage. The extra rubber negates much of the effect of the thinner threads. As so often, focusing on a single number - TPI - is misleading, because it cannot capture the subtleties involved in making a high-quality product. The most supple tires have fine threads, a moderately dense weave, and only as much rubber coating the sidewalls as is needed to protect the threads from abrasion.
一些公司宣传他们的轮胎拥有高得离谱的TPI，达到 150 甚至更高。如此细的帘线过于脆弱，根本无法用于制造自行车轮胎。事实上，这些公司是把胎体三层结构中的每一层都计算在了TPI内，所以他们宣称的 300 TPI 的轮胎，实际上相当于大多数制造商所认定的 100 TPI 轮胎。
更细的帘线也更脆弱，因此在制造过程中需要格外小心地处理。那些生产经济型轮胎的工厂，设备通常不足以应对如此精细的胎体，所以他们会给胎体涂上厚厚的橡胶，使胎体更耐损伤。但额外添加的橡胶在很大程度上抵消了细帘线带来的优势。和其他许多事情一样，只关注单一指标 TPI，是具有误导性的，因为它无法体现出制造高品质产品所涉及的微妙之处。最柔软的轮胎采用细帘线、中等密度的编织方式，并且胎壁的橡胶涂层仅达到保护帘线免受磨损所需的最少量。
Tire Width 轮胎宽度
The reason why racers have moved to 25 mm-wide tires is simple: They are faster. Bicycle Quarterly’s testing found that 25 mm-wide tires roll faster than 23 mm ones, which in turn are faster than 20 mm tires. One reason is that the contact patch of a wider tire is shorter. At the same pressure, a wider tire deflects less as it rotates. This reduces its hysteretic losses.
And if you run the wider tire at lower pressure, the suspension losses are smaller. Either way, resistance is reduced.
赛车手们改用 25 毫米宽轮胎的原因很简单：这种轮胎速度更快。《自行车季刊》的测试发现，25 毫米宽的轮胎比 23 毫米宽的轮胎滚动速度更快，而 23 毫米宽的轮胎又比 20 毫米宽的轮胎更快。原因之一在于，更宽的轮胎与地面的接触面积更小。在相同气压下，更宽的轮胎在滚动时变形更小，这就降低了其滞后损失。而且，如果你以较低气压使用更宽的轮胎，减震损失也会更小。无论哪种情况，阻力都会降低。
On smooth pavement, there is no speed benefit to tires wider than 25 mm, but also no disadvantage. Our testing found that even 53 mm-wide tires do not roll slower than narrower tires, at least at speeds of 29.5 km/h (18.3 mph).35 In these tests, we compared tires with the same supple casings, just different widths. Conversely, a wide touring tire with a stiff casing will roll much slower than a supple racing tire of any width.
在平坦的路面上，使用宽度超过 25 毫米的轮胎并不会带来速度上的优势，但也没有劣势。我们的测试发现，即使是 53 毫米宽的轮胎，其滚动速度也不会比更窄的轮胎慢，至少在时速 29.5 公里（18.3 英里）的情况下是如此。在这些测试中，我们比较的是胎体柔软度相同但宽度不同的轮胎。相反，胎体坚硬的宽幅旅行轮胎，其滚动速度会比任何宽度的柔软竞赛轮胎慢得多。
While tire width above 25 mm doesn’t make much of a difference on smooth pavement, on rough roads wider tires roll faster, because you can run them at lower pressures. This reduces the suspension losses that make up the bulk of tire-related resistance on rough pavement (see p. 42).
在平坦路面上，轮胎宽度超过 25 毫米并不会产生太大差异，但在颠簸路面上，更宽的轮胎滚动速度更快，因为你可以以较低的气压使用它们。这样能减少减震损失，而在颠簸路面上，减震损失占轮胎相关阻力的大部分（详见第 42 页）。
Tread Thickness 胎面厚度
A tire’s tread is the rubber that touches the road. A thinner tread makes the tire more flexible and thus faster, because it requires less energy to flex as the wheel rotates.
The effect is small, but significant. In our testing, a set of well-used 27 mm-wide tires with 1-1.5 mm of tread worn off was 2.1% faster than a new set of the same tires. With wide tires, tread thickness has less effect on speed, probably because the larger radius makes the tread less convex and easier to flex. When we tested brand-new 42 mm-wide Rene Herse Extralight tires and compared them with a set that had been ridden more than 6500 km (4000 miles), we found no significant difference in speed.
轮胎的胎面是与路面接触的橡胶部分。较薄的胎面会让轮胎更具柔韧性，进而使轮胎滚动更快，因为在车轮转动时，更薄的胎面形变所需的能量更少。
这种影响虽小，但很显著。在我们的测试中，一套使用过一段时间、胎面磨损了 1 - 1.5 毫米的 27 毫米宽轮胎，比同一型号的全新轮胎快 2.1%。对于宽轮胎而言，胎面厚度对速度的影响较小，这可能是因为较大的半径使胎面的弧度变小，更易于弯曲。我们对全新的 42 毫米宽 Rene Herse 超轻轮胎和一套已行驶超过 6500 公里（4000 英里）的同款轮胎进行测试后发现，二者在速度上并无显著差异。
For narrow tires, tread thickness is a compromise between speed and longevity. Since tread can be worn down safely only to a thickness of about 1 mm, a 2 mm tread will allow for only 1 mm wear. A 3 mm tread allows for 2 mm of wear, and thus will last twice as long. Making the tread thicker doesn’t offer much benefit. Since the tire wears faster in the center than on the shoulders, wearing more than 2 mm off the tread leaves a square profile to the detriment of handling.
对于窄胎来说，胎面厚度需要在速度和耐用性之间进行权衡。因为保证安全的胎面下限厚度约为 1 毫米，所以 2 毫米厚的胎面仅能承受 1 毫米的磨损。而 3 毫米厚的胎面能承受 2 毫米的磨损，因此使用寿命会延长一倍。不过，将胎面做得更厚并没有太大好处。由于轮胎中心部位的磨损速度比胎肩快，当胎面磨损超过 2 毫米时，轮胎会呈现方形的轮廓，这会对操控性产生不利影响。
Tread Pattern 胎面花纹
Tread blocks can squirm and cause significant energy losses. Both height and width of the tread blocks determine how much they squirm. Small blocks squirm more, whereas interconnected treads or negative grooves don’t slow down the tire much.
胎面的花纹块在骑行时会发生扭动，从而造成显著的能量损失。胎面花纹块的高度和宽度共同决定了它们的扭动程度。小的花纹块更容易发生扭动，而相互连接的胎面花纹或凹槽对轮胎滚动速度的影响不大。
Some dual-purpose tires have knobs that are large enough so they don’t squirm, yet small enough so they dig into mud and soft soil for traction. By arranging the tread knobs so there is always the same amount of rubber in contact with the road surface, even when the bike leans into a corner, these knobby tires can offer predictable grip on pavement, too. In effect, these tires function like slick tires with a negative tread - the negative portion of the tread is so large that only the knobs remain of the original slick surface. Designed carefully, these tires retain most of the qualities of slicks on pavement and function like knobby tires on loose surfaces.
一些多功能胎的胎面花纹大到不易发生扭曲变形，同时又小到能够嵌入泥泞和松软的土壤中以提供抓地力。通过合理排列胎面花纹块，可以让自行车即使在压弯时，与路面接触的橡胶量也能始终保持一致，这样的齿胎在铺装路面上也能提供可预测的抓地力。实际上，这类轮胎就像带有凹槽的光头胎 —— 只不过胎面的凹槽部分非常大，以至于可以把胎面本身当作凹槽，把突出的花纹块当作原本的光头胎胎面。经过精心设计，这些轮胎在路面上能保留光头胎的大部分特性，在松散路面上又能像齿胎一样发挥作用。
For racing tires, a fine tread may increase performance, since it allows the tire to conform better to the road surface without having to flex the entire tire
对于竞赛胎而言，细密的胎面花纹或许能提升性能，因为它能让轮胎更好地贴合路面，而无需使整个轮胎发生形变。
Weight 重量
The fastest tires are light because they use thin, supple casings and relatively thin tread rubber. However, weight by itself does not determine performance. Some very light tires perform poorly. Heavy tires rarely perform well, since extra material doesn’t just add weight, but also makes tires stiffer.
Tires with folding beads are lighter than those with steel beads, but there appears to be no discernible difference in performance. For a discussion of how the weight of tires and wheels affects a bike’s performance.
速度最快的轮胎都很轻，因为它们采用了薄且柔软的胎体以及相对较薄的胎面橡胶。然而，重量本身并不能决定轮胎的性能。有些非常轻的轮胎性能却很差。重型轮胎的性能通常也不会太好，因为额外的材料不仅增加了重量，也会使轮胎变得更硬。
胎圈可以折叠的折叠胎比不可折叠的钢丝胎更轻，但在性能上似乎并没有明显差异。关于轮胎和车轮的重量如何影响自行车的性能，可参考前文的相关讨论。
Tire Pressure 胎压
Tire pressure was discussed earlier (see p. 44). Consistently, we have found that higher tire pressure does not improve performance. Choose a pressure that feels good, and your bike will be as fast as it can be.
Tires with supple casings require slightly higher pressures than stiff tires. On stiff tires, the sidewalls provide much of the support that prevents the tire from collapsing during fast cornering. In extreme cases, the tire sidewalls can support the entire bicycle without any air pressure. Supple tires rely almost exclusively on air to hold up the bike. Imagine the tire casing as a rubber spring and the air inside as an air spring. The two springs work together. If you use a supple casing that is less stiff, you need to compensate by increasing the pressure.
之前的文章里已经讨论过胎压的问题（详见第 44 页）。我们一直以来的发现是，更高的胎压并不能提升性能。选择一个让你感觉舒适的胎压，你的自行车就能发挥出它的最佳性能。
胎体柔软的轮胎比胎体坚硬的轮胎需要的胎压略高一些。对于胎体坚硬的轮胎，胎壁提供了大部分支撑力，防止轮胎在快速转弯时变形。在极端情况下，胎壁甚至可以在没有任何气压的情况下支撑起整辆自行车。而柔软的轮胎几乎完全依靠空气来支撑自行车。打个比方，可以把胎体想象成一个橡胶弹簧，把里面的空气想象成一个空气弹簧。这两个弹簧共同发挥支撑的作用。如果你使用的是硬度较低的柔软胎体，就需要通过增加胎压来弥补支撑力的不足。
Despite their higher inflation pressure, supple tires are more comfortable and roll faster, because their casings absorb less energy as they flex, and because they transmit less road shock, which reduces suspension losses.
On rough surfaces - gravel, cobblestones, mud - low tire pressures offer better performance. The softer tires absorb road irregularities better, and the larger contact patch improves traction. On loose surfaces like gravel, hard cornering is impossible, and sidewall collapse is less of a concern.
尽管柔软的轮胎充气压力较高，但它们骑起来更舒适，滚动速度也更快，因为它们的胎体在形变时吸收的能量更少，传递的路面震动也更少，从而减少了悬挂的能量损失。
在粗糙的路面上，如碎石路、鹅卵石路、泥路，较低的胎压能带来更好的性能表现。更柔软的轮胎能更好地吸收不平整路面的颠簸，更大的接地面积也能提高抓地力。在像碎石这样松散的路面上，很难进行急转，所以也不用担心胎壁会在压弯过程中失去支撑力。
Experimentation is the best way to determine the optimum tire pressure. The pressure written on a tire’s sidewall is only the maximum safe pressure - it’s not the pressure you should use.
Your tire pressure needs to be high enough to prevent the tire sidewalls from collapsing during hard cornering. your pressure gets too low, you’ll first notice that your bike is running wide in corners. It will also tend to follow ruts in the road more than usual.If you lower the pressure further, your sidewalls can suddenly collapse during hard cornering.
通过实验来确定最佳胎压是最好的方法。轮胎胎壁标注的胎压数值仅仅是最大安全胎压，并非是你应该使用的胎压。
你的胎压需要足够高，以防止在压弯时轮胎胎壁失去支撑力。如果胎压过低，你首先会注意到自行车在转弯时的转弯半径变大。而且，它还会比平时更容易被路面上的车辙带着走。如果你进一步降低胎压，在急转弯时胎壁可能会突然变形。
You also want to avoid bottoming out on big bumps, as this can cause pinch flats (with tubes) or cut the tires (tubeless). The minimum safe pressure is determined by your weight, riding style and surface conditions. Some makers list minimum pressures for their tires, but they have little meaning beyond indicating that the optimum pressure lies within a broad range. Light cyclists can usually ride at less than the recommended minimum pressure.
你还需要避免在遇到较大颠簸时轮胎触底，因为这可能会导致（有内胎的轮胎）出现夹胎爆胎的情况，或者导致（无内胎轮胎）轮胎被割破，也即车友们常说的“蛇咬”。最低安全胎压取决于你的体重、骑行风格和路面状况。一些制造商列出了他们所生产轮胎的最低胎压，但这些数值除了表明最佳胎压处于一个较宽泛的范围之外，并没有太大实际意义。体重较轻的骑行者通常可以安全地在低于推荐的最低胎压下骑行。
Above the lower limit dictated by safety, you can choose your tire pressure to dial in the feel of your bike. Do you want a little give in your tires to offer beneficial flex (see p. 68)? Or do you prefer a stiffer feel?
Wider tires have a greater range between the minimum and maximum safe pressures. With quality tires, pressure does not change your bike’s speed, only its feel. Experiment with different tire pressures to tune the feel of your bike.
在安全规定的最低胎压之上，你可以根据自己的喜好来选择胎压，以调整自行车的骑行感受。你是希望轮胎有一点弹性，以便产生有益的形变（详见第 68 页）？还是更喜欢“硬核”的骑行感受？
更宽的轮胎在最低和最高安全胎压之间的范围更大。对于质量好的轮胎来说，合理范围内的胎压不会对自行车的速度有太多影响，只会影响骑行的感觉。尝试不同的胎压，以调整出你最喜欢的骑行感受。
Tubulars vs. Clinchers 管胎 vs. 开口胎
On most surfaces, tubular tires are slightly slower than clinchers. However, the effect is much smaller than previously thought. Tubular tires have higher hysteretic losses, possibly because the tire creeps on the rim. However, the round profile of the tubular allows the casing to flex around the tire’s entire perimeter, whereas a clincher can flex only on three sides, as the fourth side is made up by the rigid U-shaped rim. This reduces the tubular’s suspension losses, and it compensates for much of the higher hysteretic losses.
在大多数路面上，管胎的速度比开口胎略慢。然而，这种差异比我们之前认为的要小得多。管胎的滞后损失更高，这可能是因为车轮转动时管胎在轮辋上会产生蠕动。不过，管胎的圆形轮廓使得胎体能够在轮胎的整个周长上弯曲，而开口胎只能在三个侧面弯曲，因为第四个侧面是由坚硬的 U 形轮辋构成的。这减少了管胎的悬挂损失，并且在很大程度上弥补了其较高的滞后损失。
For narrow and medium-width tires, the shock absorption of tubulars equals that of a clincher that is about 10% wider - assuming similar casing construction. To obtain the comfort of a 25 mm tubular, you need a 28 mm clincher. However, with very wide tires - above approximately 40 mm - the rim makes up much less of the circumference of the tire, so tubular tires lose their advantage.
对于窄胎和中等宽度的轮胎来说，假设胎体结构相似，管胎的减震效果与宽度大约宽 10% 的开口胎相当。要想获得与 25 毫米宽管胎相同的舒适性，你需要使用 28 毫米宽的开口胎。然而，对于非常宽的轮胎（大约超过 40 毫米），轮辋在轮胎周长中所占的比例要小得多，所以管胎就失去了它们的优势。
Tubulars remain popular in road racing due to the lighter weight of their rims and their greater traction. In cyclocross, they used to offer a great advantage because they are much less likely to pinch-flatting, since their rims lack the sharp horns that hold clincher tires on their rims. Modern tubeless technology has eliminated the risk of pinch flats, making clincher tires a viable choice even in cyclocross. Pro racers, who are limited by UCI rules to a maximum tire width of 33 mm, still choose tubulars for their better shock absorption and traction. For amateur cyclocross racers, 38 mm wide supple clinchers offer similar performance and shock absorption.
With tubular tires, high tire pressure is slower than lower pressure on all road surfaces. A tubulars’ performance relies to a greater degree on low suspension losses. Higher pressure increases suspension losses and reduces the tubular’s performance. To optimize performance, tubulars should run relatively low pressure.
管胎在公路自行车比赛中仍然很受欢迎，这是因为它们的轮辋更轻，而且抓地力更强。在公路越野赛中，管胎曾经具有很大的优势，因为它们很少会出现夹胎爆胎的情况，这是因为它们的轮辋没有那种会夹住内胎导致“蛇咬”的尖锐边缘。现代的无内胎技术已经消除了“蛇咬”的风险，这使得开口胎即使在公路越野赛中也是一个可行的选择。职业赛车手受到国际自行车联盟（UCI）规则的限制，轮胎的最大宽度为 33 毫米，在这种情况下他们仍然会选择管胎，因为管胎具有更好的减震效果和抓地力。对于业余公路越野赛选手来说，38 毫米宽的柔软开口胎也能提供类似的性能和减震效果。
在所有的路面上，给管胎打上高胎压后的行驶速度都比低胎压时慢。管胎的性能在更大程度上依赖于较低的悬挂损失。胎压较高会增加悬挂损失，进而降低管胎的性能表现。为了优化性能，管胎应该使用相对较低的胎压。(Lower than 开口胎？这与我的认知不符)
Tubes 内胎
Thin, lightweight tubes probably reduce the rolling resistance of tires, but the effect is small. In our testing, the difference between ultra-thin and standard tubes was not statistically significant. However, high-quality latex tubes roll significantly faster than butyl tubes.
薄且轻质的内胎或许能降低轮胎的滚动阻力，但这种效果很微弱。在我们的测试中，超薄内胎和标准内胎之间的差异在统计学上并不显著。然而，高质量的乳胶内胎明显比丁基内胎的滚动阻力更小。
Tubeless 无内胎
Tubeless tires eliminate the tube altogether. The tire sits tightly on a specially designed rim that forms an airtight seal with the tire. True tubeless tires must have air-tight sidewalls, which requires an extra rubber membrane that makes the tires stiffer and slower than standard tires.
The thin sidewalls of supple tires are not airtight. However, sealant can be used to make supple tires airtight, so they can be run tubeless. Sealant also has the advantage that it seals small punctures, thus preventing many flats. If a puncture is too large to be sealed, the rider will have to install an inner tube.
Eliminating the tube makes the tire more supple, but liquid sealant inside the tire adds friction. The two effects cancel each other. Setting up tires tubeless is useful for rough terrain where it eliminates the risk of pinch flats, but it’s not faster than running butyl tubes, and slower than using latex.
无内胎系统的轮胎（真空胎）完全不需要内胎。真空胎紧密地安装在专门设计的轮辋上，与轮胎形成气密密封。真正的真空胎必须有气密的胎壁，这就需要额外的橡胶膜，这使得这种轮胎比一般的轮胎更硬，滚动速度也更慢。
柔软轮胎的薄壁胎壁并不气密。然而，可以使用补胎液使柔软的轮胎达到气密状态，这样它们就可以无内胎使用。补胎液还有一个优点，就是它能补上小的扎胎口，从而避免许多爆胎情况的发生。如果扎胎口太大无法被密封，骑手就不得不塞一个内胎进去才能继续骑行。
去掉内胎会使轮胎更柔软，但真空胎内的液体补胎液会增加摩擦。这两种效果某些程度上相互抵消。对于崎岖地形来说，使用无内胎轮胎是很有用的，因为它消除了夹胎爆胎的风险，但它并不比使用丁基内胎的开口胎更快，相比使用乳胶内胎时速度反而还要更慢。
Temperature 温度
Warm tires roll faster, because rubber becomes softer at higher temperatures. This effect is very significant, with speed differences of 8% or more between warm and cold days.43 More importantly, grip is also much-reduced at temperatures below 10°C (50°F). If you are trying to set a record, your chances of success are higher on a warm day.
温热的轮胎滚动得更快，因为橡胶在温度较高时会变得更柔软。这种影响非常显著，在春暖花开和三九严冬的日子，轮胎滚动速度差异可达8%甚至更多。更重要的是，当温度低于10摄氏度（50华氏度）时，轮胎的抓地力也会大幅下降。如果你想要创造一项纪录，那么在天气暖和的日子里，成功的几率会更高。
New vs. Broken-In 新胎 vs. 旧胎
New tires can have higher resistance than tires that have been broken in for a few hundred kilometers. The difference amounted to about 3.5% on one particular tire with a relatively coarse tread pattern. It is likely that the edges of the tread blocks are worn smooth, thus decreasing their resistance. It is also possible that the threads in the casing loosen up a bit and thus reduce the resistance of the tires.
新胎的滚动阻力可能会比已经磨合了几百公里的旧胎更大。对于某一款胎面花纹相对粗糙的特定轮胎来说，这种差异大约达到3.5%。很可能是因为胎面花纹块的边缘在使用过程中被磨得光滑了，从而降低了其滚动阻力。也有可能是胎体中的帘线稍微有些松动，进而减少了轮胎的阻力。
Acceleration 加速性能
Wider tires inevitably are heavier than narrow ones. The difference is smaller than many cyclists imagine, because the casing of high-performance tires is thin and does not weigh much. The tread rubber of wider tires can also be thinner, since the wear is spread over a larger surface. The beads are the same for tires of any width. The weight of the extra air inside is negligible. Wide tires with supple, lightweight casings offer much greater air volume for a small weight penalty.
较宽的轮胎不可避免地会比窄胎更重，但这种重量差异比许多骑手想象的要小。因为高性能胎的胎体很薄，本身重量不大；宽胎的胎面橡胶也可以更薄，因为磨损会分散在更大的接触面上。无论轮胎宽度如何，胎圈的重量都是相同的。而轮胎内额外增加的空气重量可以忽略不计。带有柔软、轻质胎体的宽轮胎，只需增加少量的重量，就能提供大得多的空气容量。
This means that wider tires accelerate only very slightly slower than narrow ones (see p. 52 for a discussion of wheel weight and acceleration). Furthermore, the extra weight of wider tires can be compensated by using smaller wheels, so the rotational inertia remains the same: That way, a wide tire can accelerate as fast as a narrow one.
这意味着宽胎在加速性能上仅比窄胎稍慢一点点（关于车轮重量与加速性能的讨论，详见第52页）。此外，宽轮胎多出的重量可以通过使用较小尺寸的车轮来弥补，这样转动惯量就能保持不变：通过这种方式，宽胎的加速性能可以比肩窄胎。
Tire Pressure and Power Output 胎压与功率输出
With wide tires, tire pressure can be used to tune the bike’s flex characteristics and maximize the rider’s power output (see p. 58 on ‘planing”). Wide tires will perform and feel different depending on their pressure. Experiment with tire pressure to figure out what works best for you.
使用宽胎时，可以通过调整胎压来调节自行车的弹性特性，并使骑手的功率输出最大化（详见第58页）。根据胎压的不同，宽胎的性能表现和骑行感受也会有所不同。尝试不同的胎压，找出最适合你骑行风格的胎压设置。
Cornering 过弯
Wide tires have much more cornering grip. Two factors are at play here. First, the wider tire simply puts more rubber on the road. This means that there are more interlocking interfaces between tire and road surface, and thus more grip. That is why race cars use wide tires.
宽胎在过弯时的抓地力要强得多。这里有两个因素在起作用。首先，更宽的轮胎显然会让更多的橡胶与路面接触。这意味着轮胎和路面之间有更多相互咬合的接触面，因而抓地力更强。这也是方程式赛车使用宽到夸张的轮胎的原因。
Wider tires also run at lower pressures, so they adhere better to the road surface, rather than skipping over irregularities like a narrow high-pressure tire. When a narrow tire loses contact as it skips, it momentarily breaks traction. This reduces the cornering limit of the tire. If the tire tread is always in contact with the road surface, grip will be maximized. This effect is especially pronounced on rough and bumpy roads.
宽胎的胎压也更低，所以它们能更好地贴合路面，而不会像窄的高胎压轮胎那样在不平整的路面上跳滑而过。当窄胎在跳滑时失去接触，它会在瞬间失去牵引力。这就降低了轮胎的过弯极限。如果轮胎胎面始终与路面保持接触，抓地力就能达到最大化。这种效果在粗糙不平和颠簸的路面上尤为明显。
Casing suppleness also plays a role in cornering traction. A supple tire will absorb more irregularities, and thus keep the tread in better contact with the road surface.
胎体的柔软度也对过弯时的牵引力有影响。柔软的轮胎会更好地吸收路面的颠簸，从而使胎面与路面保持更好的接触状态。
Rim Width and Cornering
The width of the rim changes the profile of the tire. With a wider rim, the tire becomes U-shaped rather than O-shaped, and, in theory, the sidewalls can support greater loads. This is said to improve cornering.
However, the sidewalls of supple tires are not stiff enough to support significant weight. The extreme example are tubular tires, which are completely O-shaped. Professional racers run tubular tires in part because of their superior handling - further evidence that with supple tires, rim width does not affect handling.
轮辋的宽度会改变轮胎的外形轮廓。使用更宽的轮辋时，轮胎会变成U形而非O形。从理论上讲，O形的胎壁能够承受更大的载荷，据说这有助于提升过弯性能。
然而，柔软轮胎的胎壁硬度不足以支撑较大的重量。一个极端的例子是管胎，它们完全是O形的。职业赛车手使用管胎的部分原因就在于其出色的操控性能——这进一步证明了对于柔软的轮胎来说，轮辋宽度并不影响操控性。
Supple tires rely almost exclusively on air pressure to resist cornering forces. Supple tires must be inflated a bit harder to make up for the reduced casing stiffness (seep. 142), but even stiff tires can collapse during hard cornering, if they are not inflated enough: As the tire compresses, it always becomes more O-shaped, reducing its ‘spring rate’ and making it easier to compress it further.
The optimal pressure for cornering is low enough to keep the tire from skipping over bumps, but high enough that the sidewalls don’t collapse.
柔软的轮胎几乎完全依靠胎压来抵抗过弯时产生的侧向力。因此，柔软的轮胎必须有足够的气压，以弥补胎体硬度的不足（详见第142页），但即便是较硬的轮胎，如果充气不足，在急弯时也可能会失去支撑力：当轮胎受到挤压时，它总会变得更趋近于O形，从而降低其“弹簧刚度”，使其更容易被进一步挤压变形，从而失去支撑力。
过弯时的最佳胎压应足够低，以防止轮胎在颠簸路面上跳滑而过，但也要足够高，以确保胎壁不会失去支撑力。
Optimizing Tire Tread 胎面最优解
Tire tread has numerous functions, yet it is often misunderstood. On car tires, tread patterns mostly serve to evacuate water from the contact patch to prevent hydroplaning.
Bicycle tires don’t hydroplane, and in the past, many believed that the most logical tire tread pattern was none at all - a perfectly slick tire. Even today, many tire manufacturers consider tread patterns mostly ornamental.
轮胎的胎面有许多功能，可惜它们常常被误解。对于汽车轮胎来说，胎面的花纹主要是为了将接触面上的水排出，以防止车辆发生水滑现象。
自行车轮胎不会出现水滑现象，因此在过去，很多人认为最合理的自行车胎面花纹就是根本没有花纹 —— 也就是完全光滑的光头胎。即使在今天，许多轮胎制造商仍然认为胎面花纹大多只是装饰性的。
This overlooks that a well-designed tread pattern can interlock with the pavement and increase cornering traction. This effect is especially pronounced in the wet, but it is important even on dry roads. The best tread pattern has as many small edges as possible to interlock with road surface imperfections. The traditional chevron or file tread pattern found on many classic high-performance tires works very well in this respect.
这就忽略了一个事实，即设计良好的胎面花纹能够与路面相互咬合，从而增加过弯时的抓地力。这种效果在潮湿路面上尤为明显，但即使在干燥路面上，它也非常重要。最佳的胎面花纹应具有尽可能多的小边缘，以便与路面的不平整处相互咬合。在许多经典的高性能胎上常见的传统V形或锉刀状胎面花纹在这方面的效果就非常好。
Why are fine ribs used on bicycle tires, but not for cars or motorcycles? Car tires are square, because they don’t lean into corners. Their entire surface is in contact with the road at all times, and ribs would wear away quickly. Motorbikes have too much power to make fine ribs practical. They weigh much more than bicycles, so their tires are pushed into the road surface and interlock more firmly with the pavement. On bicycle tires, the shoulders that touch the road during cornering do not experience significant wear. Fine ribs improve cornering grip and last as long as the tire.
为什么自行车轮胎会使用细密的肋状花纹，而汽车或摩托车轮胎却不使用呢？汽车轮胎是扁平的，因为汽车在过弯时不会倾斜。汽车轮胎的整个表面始终与路面接触，如果有肋状花纹，很快就会磨损掉。摩托车的动力太大，细密的肋状花纹对它们来说并不实用。摩托车比自行车重得多，所以它们的轮胎会被压入路面，与路面的咬合更牢固。对于自行车轮胎来说，过弯时与路面接触的胎肩部分并不会出现明显的磨损。细密的肋状花纹能够提高过弯时的抓地力，而且其使用寿命和轮胎本身一样长。
An optimized tread pattern is divided into several parts. In the center of the tire, the tread wears, so it doesn’t serve much function beyond acting as a wear indicator. When the bike leans over during cornering, the tire rolls onto its shoulder.
Traction is crucial in this situation, and the tread pattern here should be optimized for interlocking with the road. Beyond the shoulders, the edge of the tire does not touch the ground, but the casing still is exposed to sharp rocks and other debris.
Here, a smooth tread protects the casing from damage.
最优的胎面花纹可分为几个部分。在轮胎的中心部位，胎面会磨损，所以除了作为磨损指示标志之外，花纹并没有太多其他功能。当自行车在过弯时倾斜，轮胎会向胎肩部位滚动。
在这种情况下，抓地力至关重要，此处的胎面花纹应经过优化，以便与路面更好地咬合。在胎肩之外，轮胎的边缘部分并不接触地面，但胎体仍然会暴露在尖锐的石头和其他碎屑面前。在这里，光滑的胎面可以保护胎体不被损坏。