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| Geometry |
 In mathematical geometry, there's nothing quite as strong as a triangle. Diamond-frame bikes consist basically of two triangles. The elegance and simplicity of this design is very hard to improve upon. Billions of diamond-frame bikes have been made from tubing for over a century, and during that time, hundreds of thousands of very smart people have spent billions of hours riding along and thinking about ways to fine-tune the performance of their bikes. The tubular diamond frame has been fine tuned by an evolutionary process to the point where it is very close to perfection, given the basic design and materials.
Bikes have “trail” and without it you’d be falling off them often. "Trail" causes the wheel of a bike to self-center, in the manner of a shopping cart's caster wheel. It's trail that keeps the bike upright. In order to have "trail" the front wheel’s contact patch—the place where the rubber literally meets the road—must fall behind the point where the bike's steering axis would, theoretically, meet the road. The further the contact patch falls behind the steering axis, the more trail there is and the more likely the bike will want to go in a straight line.
Speed wobble, Death wobble, or front-end shimmy is just an inherent "flaw" of bicycles. Bicycle frames are amazingly stiff and strong in a vertical plane, but horizontally they are not. When a bicycle is moving in a line straight ahead, and gyroscopic effects of the wheels weigh on a unit as elastic as a bicycle frame-with its for and wheels-you might get shimmy. Shimmy occurs at a certain speed, depending on the bike and the rider. It's been said that every bicycle is prone, depending on its geometry, materials, and rider position, a particular resonant frequency, at which the bicycle oscillates. All that occurs when a given speed is reached on a descent. |
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| Frame Materials |
 The frame material of a bike affects its stiffness, weight, and strength. So it's important to get a material with a proper mix of these characteristics that's appropriate for your biking activities. There are basically four different types of bicycle frame materials Steel, Aluminum, Carbon Fiber, and Titanium. Steel is heavy, but is stiff. A frame made with steel will usually have small tubes. To help reduce weight many steel frames have thin walled tubes, which lessen the overall stiffness. Some of the positive characteristics of steel are that it’s very strong, provides a stiff ride, durable, and cheap. Its negative characteristics are it’s heavy and prone to rusting. Aluminum is one of the most common frame materials because it is light and fairly affordable. Aluminum provides the rider with a very stiff ride and is often used for unique frame shapes. Aluminum frames have large diameter tubes that help improve strength and stiffness. The positive characteristics of Aluminum are, it’s light, stiff, inexpensive, and rust proof. Some of Aluminum’s negative characteristics are, it has less strength than steel, can break under heavy use, it’s difficult to repair, and it’s thin walled tubes dent easy. Carbon fiber frames are very strong and stiff. They are made by braiding fibers of carbon and affixing them with a very strong glue or epoxy. These kind of frames allow for unique frame shapes because they can be molded to the proper shape much easier than metal alloys. Its positive features are its great strength, its stiffness, it’s very light, and it doesn’t rust. Some negative aspects of Carbon fiber are it’s expensive and it’s prone to breakage. Titanium combines a great balance of lightness, strength, durability, and stiffness. The best alloys of titanium are as strong as the best alloys of steel frames. Titanium frames usually come in two alloys: 3A/2.5V alloy 3% aluminum / 2.5% vanadium or 6A/4V alloy 6% aluminum / 4% vanadium, being stronger but more expensive. Titanium is super light, very strong, rust proof, and great for large riders. However, Titanium is very expensive and somewhat flexible compared to steel. |
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| Clothing Materials |
 Much of cycling clothing is made of, or partially made of Polyester for its wicking properties that are hard to match by any other fabric, natural or man-made. Acrylic is often used in insulation layers because it is inexpensive and has good insulation properties. Neoprene is non breathable, water resistant thermal material. It offers excellent protection from cold and used in fabric for shoecovers and gloves. Nylon spandex, the base for most cycling-short fabrics has great stretch and durability. However, nylon spandex does not have the ability to wick moisture, a major benefit when you're sweating, and breathe until a finish is applied, or until the fabric is knitted a special way. For example, spandex is now mixed with other yarns such as polyester to promote moisture transfer and breathability. |
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| Components |
 There are many different components of a bicycle. The parts that you can immediately see are: The frame, the wheels, The saddle and seatpost, the handlebars and the handlebar stem, the cranks and pedals, the brakes, and the chain and gears. The frame of a bicycle is one of the most important components, defining the comportment of the bicycle on the road and making up a great amount of the overall material. The next most important part of a bicycle is the wheels, which make it all move. The wheels are made of a hub, the spokes, the metal rim, and the rubber tire. The seat post connects the saddle to the frame of the bicycle. Race bicycles usually use really stiff saddles enabling the maximum energy transfer from cyclist’s legs to the pedals. The handlebar stem, or stem connects the handlebars to the frame. The brakes consist of: the actuators on the handlebars, the brake cable, the brake calipers and the brake pads. The chain and gears, consist of the front chain wheels, the rear freewheel, the front and rear derailleur, the shift levers on the handlebars and the cables. The gears of a bicycle make pedaling more efficient, allowing the cyclist to travel faster and handle steep grades and other obstacles more easily. |
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| Aerodynamics |
 Aerodynamic drag, wind resistance plays an important role in cycling. In fact, at 8 mph, 3.5 meters/second, the aerodynamic drag of a bicycle and rider is greater than the rolling resistance, wheels on the ground. At 20 mph, 11 m/s, the aerodynamic drag is more than 80% of the total drag. The rider causes 65% to 80% of the drag. Therefore, the rider's position is very important. The crouched racing position and the drop handlebars have been used since the 1890's. Proper body position can reduce drag by 31% over an upright riding position. New handlebars have allowed riders to achieve an optimal aerodynamic position. This position is head down, back straight. This still allows for efficient pedaling. In this position drag is reduced by 25%. A helmet can also help to decrease the aerodynamic drag, by about 2%. In fact, modern aerodynamic helmets result in a lower drag even for a bald bicyclist. A typical bicycle wheel is made of a hub, a rim, and 32 or 36 spokes. As the wheel rotates, the air flow separates causing turbulence, which in turn increases drag. Aerodynamic rims help to decrease the drag. Solid disk wheels and three-spoke wheels eliminate the pressure drag with typical wheels. Today's lighter materials make these more usable. The drag of these aerodynamic wheels decreases or increases depending on the crosswind. The crosswind can cause drag or lift. Reducing aerodynamic drag is especially important in bicycle road races. Road races usually include many riders. When riding in a pack, the riders in the front use 30% to 40% more energy than the riders in the middle of the pack. When a rider breaks away from the pack he must time it carefully to win. As soon as he leaves the pack he takes the full force of the wind. This means the others may catch up soon. However, by taking turns a rider at the front of the pack may drop back to rest up. The lead bike would break the wind allowing the single rider to take advantage of less drag and therefore greater speed. This is called drafting. This method allows the pack to maintain a higher average speed than an individual rider. |
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| Fitness |
 Bicycling has several advantages over other exercises. Cycling is as effective as walking and running for toning large muscles of the lower body, however it exercises the heart better than walking without the pounding of jogging. At a low cost, a bicycle can be ridden almost anywhere, at any time of the year. Little or no time has to be lost, as bike travel can be used to get to work, perform errands, or enjoy the outdoors. Commuting by bike reduces pollution that causes asthma and bronchitis. A commuting cyclist is also less exposed to air pollution than a commuting motorist. Cycling on a regular basis reduces the cholesterol levels in the blood. It increases the high-density lipo protein/cholesterol ratio in the blood as well. Cycling reduces the chances of strokes and heart attacks caused by clotting, and reduces the chances of illnesses caused by high blood pressure. It is as effective as drugs in reducing high blood pressure and makes obesity unlikely thus helping reduce the chances of diabetes. |
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| Tires |
 A bicycle is only as good as its tires. Tires affect every aspect of performance—cornering grip, acceleration, braking, and ride quality—and they do their work through two amazingly small contact patches. Many people suppose that tires are made out of rubber, because that's what is visible. This is a major oversimplification--rubber is the least important of the three components that make up a tire. The "bead" is the edge of the tire. On most tires, the beads consist of hoops of strong steel wire. The beads are what hold the tire onto the rim, and are, in a sense, the "backbones" of a tire. While most beads are steel, some tires use Kevlar cord instead. Using Kevlar for this purpose typically saves about 50 grams, 2 ounces per tire. Since Kevlar is much more flexible than steel, tires with Kevlar beads can be folded up compactly, which is convenient for touring or other applications where it may be advisable to carry a spare tire. Cloth fabric is woven between the two beads to form the body or "carcass" of the tire. This is the heart of the tire, the part that determines its shape. The vast majority of tires use nylon cord, though some use polyamide. Up until the 1960s, cotton/canvas was commonly used. The fabric threads don't interweave with crossing threads as with normal cloth, but are arranged in layers or "plies" of parallel threads. Each layer runs perpendicular to the next layer(s). Some tires use thick thread, some use thin thread for the fabric. With thin thread, there are more threads per inch ("TPI") and this number is often considered an important indication of tire performance. The higher the TPI number, the thinner and more flexible the tire fabric is. Thin-wall (high TPI) tires tend to be lighter and have lower rolling resistance, but they're more easily damaged by road hazards. Some bicycle tires also have a Kevlar belt running under the tread area, in addition to the normal bias plies. This is intended as a puncture preventive. Once the fabric has been woven between the beads, and the tire has its basic shape, it is coated with rubber. The rubber is mainly there to protect the fabric from damage, and has no structural importance. The rubber that comes into contact with the ground is called the "tread." This area usually has thicker rubber than the "sidewalls" of the tire, mainly for wear resistance. Most tires have some sort of 3-dimensional pattern molded into the tread, which may or may not enhance traction. Manufacturers mix different additives with the rubber to achieve desired traction/wear characteristics. Generally, a softer formulation will give better traction, but at the expense of more rapid wear. Rubber is normally a sort of tan color, but most tires are black. This is the result of adding carbon black to the mix. Carbon black considerably improves the durability and traction of the rubber in the tread area. Some manufacturers substitute a silicon compound for the carbon black. These tires usually have a gray tread. Whether silicon or carbon black provides better traction is subject to dispute. "Dual compound" tires feature a center strip of fairly hard rubber for improved wear, with a softer, grippier formulation toward the sides of the tread. The intent is to provide better cornering traction without compromising the lifespan of the tread. Many bicycle tires are "gumwalls" or "skinwalls." Gumwall tires have tan sidewalls, with no carbon black. This may make the sidewalls slightly more flexible, reducing rolling resistance. It is not clear to what extent this makes a difference. Skinwalls have either no rubber on the sidewalls, or a very thin layer. This too is an attempt to make the sidewall more flexible and reduce rolling resistance. |
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| Tubular Tires |
 For years the only choice for a high performance cyclist was tubular tires. There are two basic kinds of tubular tires, Vulcanized and Hand made. A vulcanized tubular is more prone to flats. The tread was vulcanized to the flat fabric of the casing. With 100+ psi in the inflated tubular, the tread is stretched several centimeters longer around the outer circumference of the tire. Once the tread receives a road cut, the tread's tension will cause the cut to open up. The strain of this tension also causes the vulcanized tire to be less flexible and slightly increases rolling resistance. Hand-Made Tubulars. Hand-made tubulars are works of art. The casing fabric of a hand-made tubular is not woven. Very fine threads, up to 320 per inch, are laid next to each other, compressed and then bonded with a latex coating. A good tubular will have over two kilometers of thread. These threads were traditionally cotton or silk. Now polyester is usually used. The threads are not interwoven as in a normal fabric. The first ply is laid on a round form. Then, another ply is laid at a 45 degree angle on top of the first one. They are bonded with heat (but not vulcanized) and the edges are folded over. The result is a casing of incredible strength and flexibility.
Hand-Made Tubulars. Hand-made tubulars are works of art. The casing fabric of a hand-made tubular is not woven. Very fine threads, up to 320 per inch, are laid next to each other, compressed and then bonded with a latex coating. A good tubular will have over two kilometers of thread. These threads were traditionally cotton or silk. Now polyester is usually used. The threads are not interwoven as in a normal fabric. The first ply is laid on a round form. Then, another ply is laid at a 45 degree angle on top of the first one. They are bonded with heat but not vulcanized and the edges are folded over. The result is a casing of incredible strength and flexibility. The edges of the fabric are sewn together as an inner tube, usually of natural latex rubber, is inserted. A base tape is glued to the inner circumference to protect the stitches.
The tire is then inflated and the tread is hand-glued to the tire casing.
The tension between the casing and the tread that was found in the vulcanized tire is eliminated, making the tire more flex. The tire doesn't flat as easily because cuts don’t open up as quickly. The tire, with its superior suppleness and flexibility has a much nicer feel. The unwoven casing also has benefits for the rider. The casing is so supple that when the tire rolls over irregularities in the road, a smaller area of the casing deforms compared to woven casings. This decreases rolling resistance. The tire is therefore faster. The high-thread-count casing resists the penetration of sharp objects. Flats occur less often. The tires are less prone to other road damage because the casing is so strong. In professional racing, if the rider is not paid to ride clinchers, he will, if at all possible, ride tubular tires. The flexibility of the casing not only makes the tire faster, it handles better. The supple casing allows the tread to grip the road. The reduced harshness of the ride means more miles with less fatigue. Hand made tubulars are very expensive, but they remain the finest tires a rider can put on his bike. An open tubular is a tubular tire whose edges have not been sewn together. Instead, a flexible bead of kevlar is sewn along the edges turning it into, if I may be allowed to mix up my definitions here for a second, a clincher that performs almost as well as a tubular. All the techniques of making the tubular, the high-thread-count unwoven casing and the cold-treated tread application are used in the manufacturing of Open Tubulars. Similarly, open tubulars high-thread-count casing makes them strong, while able to roll fast and resist punctures. The cold-treated application along with the fine casing gives the tires a wonderful feel. |
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| Clincher Tires |
 Conventional tires used on 99% of all bicycles are "clincher" type, also known as "wire-on." They consist of an outer tire with a u-shaped cross section, and a separate inner tube. The edges of the tire hook over the edges of the rim, and air pressure holds everything in place. A clincher tire has a woven fabric casing. This casing is almost always nylon. Clinchers, being vulcanized, are generally cheaper than open tubulars. A clincher can have a metal and therefore rigid bead, or one of flexible kelvar or glass fiber. These tires can be folded and are far lighter than their metal beaded equivalents. The metal beaded tire, while far cheaper, gives a harsher ride. A good, high-end clincher on a hand-built cross three spoke wheel gives a wonderful ride. The tread vulcanized onto clinchers is generally thicker. For this reason, a clincher tire will usually last longer. |
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| Cycling as a Team Sport |
 It may be surprising to learn that cycling is one of the most strategic team sports. In a typical pro race, teams have eight to twelve riders on the start line. Each team has its own game plan for winning and each rider plays a different role in that game plan. Most teams have one leader whose teammates play the role of domestique and sacrifice their own chances of winning in support of their team leader. A domestique is the "worker ant" of the team, by protecting the leader from the wind, chasing down breakaway riders, fetching food or clothing for the leader and even sacrificing their bikes' parts to give to their leader if he has a mechanical problem. Few riders can win a long race on their own. Even Lance Armstrong depended heavily on the strength of his team to have seven Tour de France victories. Understanding this team aspect in cycling will make it even more exciting. One of the most crucial concepts in team racing is drafting. Riders can conserve energy by riding in the slipstream of another cyclist. As a result, teams try to surround their leader with teammates, keeping him out of the wind and fresh to attack at the right moment. Different formations can increase the energy-saving benefits of drafting, and wind can necessitate a variety of drafting formations. In a headwind, this formation is a long straight line that is called a paceline. In a crosswind, riders will form staggered, diagonal lines that are known as echelons. Teams also develop complex strategies to win specific stages and the races within races, such as points for the Mountain or Sprint competitions. Not only do teams designate a leader for the overall race, but many also select riders to try and win the best sprinter and best climber competitions. |
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