The Bike Wheel mounted with steel spokes was invented more than 120 years ago, to replace the first bike wheel made entirely of wood, similar to the wheels of a carriage. It not only greatly reduced the weight, but had its durability significantly increased. Today, a bike wheel can withstand more than 100 times its own weight, and in the most extreme off-road conditions, they support peak loads that exceed a quarter of a tone!
THE ROLE OF EACH COMPONENT
This marvel of engineering is divided into three main parts:
Cube: the core of the bike wheel, responsible for 40% of lateral stiffness and vertical absorption, arising from the diameter and distance between the flanges and the body shape. It also houses bearings and shaft, plus the ratchet / free wheel mechanism in the rear hub.
Rails and nipples:
They are the “core” of the bike wheel, and also account for 40% of rigidity, which can be increased or decreased depending on the amount and thickness used in the assembly. The influence of the chosen mounting pattern (crossed or not) is less than the amount and type of radius used – smooth, drawn, aero etc.
It gives shape; is responsible for 20% of wheel stiffness. Its profile dictates the rolling characteristics (rougher or softer) and aerodynamics. On bicycle models with conventional brakes, it serves as a brake shoe for shoes. Its weight affects the inertia, that is, in the reactivity to the retakes and accelerations.
HOW TO CHOOSE A BIKE WHEEL
Wheels, just as the frame and the rest of the set, should reflect the experience that the rider seeks during his pedals, as well as suit his weight and power. There are currently as many combinations that it is possible to buy ready or assemble a pair of wheels ideal for each situation, since a single model probably will not meet all the demands, for all situations.
According to popular belief, the first prerequisite for a bike wheel upgrade is lowering weight. Of course, in the case of a bicycle powered by limited human power, this is relevant, but it is not the most important factor. The total weight of the pair helps to make the bike lighter and, depending on its location and distribution on the wheel, influences the inertia (getting out of the rest state), but it is not the most important factor either.
This item is super important for road cycling, especially in flat or slightly wavy and rolled circuits, where short, steep and successive climbs do not predominate. Taking into account that most of the time the average speed will be stable, overcoming the air resistance and generating less turbulence will certainly result in higher speed with less effort.
Format, rim profile height and width are responsible for a significant improvement in aerodynamic penetration and also for bike wheel stability in front of cross and side winds. Nothing scarier than losing control of the bike in the face of a strong gust of wind, or nothing more frustrating than spending energy controlling the steering bike wheel because of its inefficiency in the face of crosswind.
When we mention rigidity, it can be divided into global, lateral and torsional. Global is the combination of lateral and torsional. Lateral is the ability to withstand lateral deflection, assisting in accelerations (pickups and sprints) and steering precision. And torsional is the ability to withstand the traction imposed by the transmission and braking. No use having light wheels if the energy placed on them is lost in lateral deviation.
The materials that make up the main parts of a bike wheel certainly influence performance and, more importantly, durability and versatility.
The most common material is undoubtedly aluminum. The quantity and variety of profiles, alloys, widths, finishes, types of construction and reliability of the hoops manufactured with the metal attest the level of evolution reached. In terms of mechanical properties, the aluminum deforms (crumbles) before breaking and can continue to operate for a long time.
With advances in the fabrication of carbon fiber composite components, it is common to find high-performance road or MTB bike wheels that take advantage of the fantastic qualities of the material, such as low weight, rigidity, strength and vertical impact absorption capacity.
For road bike wheel, the carbon allows high profile hoops (60 to 80 mm), as well as weight and mechanical qualities that cannot be imitated by aluminum. However, the technology, although quite evolved, is in rapid evolution, but the price still restricts its acquisition. With each new generation, designers find solutions to deal with the demands on the component, delivering more performance and, especially, greater durability, which is their Achilles heel.
Another point that is starting to improve is the quality of the braking on the models used with rim brakes, something that even today put its users at a disadvantage, especially when facing humid weather. Aluminum in this respect is much more reliable and consistent than carbon, although it is rapidly changing in newer models.
It is clear that if the objective is solely and exclusively high performance, the choice for carbon (if possible) can yield excellent results. But if you rely on something totally reliable, robust and cost-effective, aluminum is still unbeatable.
I have already mentioned that, being important pillars of the structure, the best quality models are made of stainless steel and are born from rolls (like a roll of wire) and gain final form through cold mechanical work (drawing, forging and rolling), which make them more resilient.
Flat (constant thickness), variable thickness (larger at the ends than at the center) and aero models (with blade center) are available for different purposes.
Another important item to consider when choosing a pair of wheels for a particular function is the type of spoke. The most common is with the “J” head, which depending on the quality, shape of the flange where it rests and procedures performed during assembly, yields excellent durability and performance. A wheel for training or cycling in remote locations, mounted with J-head radii, will certainly be easier to repair due to the ease of replacement, as this type of lightning is easy to find than the more specific ones.
Another widely used model is the straight head ray. Although present in an increasing number, it is much less common than the traditional, in “J”. There are also spokes made of aluminum and carbon fiber, with incredible performances, but always on bike wheel with extremely high final value, which puts them out of reach of most consumers.
The spokes are connected to the rings through nipples, through threads. The threads of the highest quality rays are rolled – to distinguish them, it is only to measure the diameter, which is greater than the diameter of the ray itself – and the threads of the most economical, cut.
Nipples are also found in different materials, the most common being nickel plated brass and the most sophisticated in anodized aluminum. To assist in the maintenance of lightning stress, there are models with threaded treatment that eliminates the need to use a screwdriver during assembly. The best quality nipples usually have the tool machining surface better machined, to avoid deformation during the rationing tenure.
The vast majority of the best quality cubes have their body in cast or forged aluminum, but there are models with parts in carbon and some rare in fully carbon composite. The flanges that receive the spokes may be high or low (as explained above), angled or perpendicular. And more or less spaced, directly affecting the lateral stiffness, the absorption capacity and the tensile strength, depending on the design of the wheel.
The bearings can be from the traditional ones – with tracks, cones and separate balls, that vary of quality drastically between the basic models and the top of line, in terms of tolerances, finish of the tracks, precision of the balls, hardness of the materials etc. – as sealed cartridge, usually in steel alloys, with balls in retention collars (or not), in a greater or lesser number and, in the same way as the traditional, separate cone and lane, with materials and tolerances that make them more fast and sometimes durable than the more economical models.
There are also ceramic ball bearings and steel tracks of loftier alloys, with tight tolerances, providing the least possible friction and resulting in sensitive gains in power and speed.
The shafts can be in different alloy steel and treatments, or in harder alloy aluminum. But there are some rare models in titanium. The anchorages to the frame vary between those with locking nuts and locking axes. Locations can be made entirely of steel or with parts in aluminum (lever and nut), and shaft in steel or titanium. Through shafts are generally made from aluminum, from harder alloys (7000 series).
Finally, the ratchet mechanism, which has been integrated into the cube with the improvement of the Freehub, by Shimano – which will be the only one mentioned in this article, as it has become standard in the segment of bike wheel with better quality -, is composed of a movable body which receives the set of pinions (cassette), made of steel, titanium or aluminum, and has ratchet mechanism which can be of some different types and is invariably made of treated steel, being the most suitable material to withstand the requirements imposed on the part.
It is worth mentioning that the quality and type of ratchet coupling system varies drastically between the number of splines / notches for engaging and the number of tongues or the popular little monkeys (two, three, four, six, or two toothed rings with up to points of engagement). The evolutions have brought faster-engaging models – with smaller engagement angles, for more immediate responses -, and are more resistant to load and water elements, dust etc.