The tires (or covers) of our MTB are an element that is sometimes overlooked when compared to other, more technologically ” attractive. ” But we must not forget that the tire depends on performance, safety and comfort of our tours also riding a mountain bike. The characteristics of the two points of contact with the road, that is, the front and rear wheels, have a great influence on various aspects of the overall control of the bike.
Fortunately, the range of products available is very wide and there are many valid solutions cheap. As always, for the best choice to be considered the characteristics of the bike, the type of favorite routes, driving style and personal preferences, there are compared to other parts, fewer hassles of shopping because the prices of the covers are generally in order of a few tens of Euros. Let us now look in more detail the various elements that make up the structure of the covers for MTB.
The carcass.
The structure of the tire is made from the carcass of nylon on which is located the tread and that draws the overall shape of the tire, with a section which may be more rounded or more square. The carcass has a structural function, but also dynamic, because it can deform due to the stress incurred in contact with the ground and when it confronts a curve. Consequently, different carcasses have different behaviors and affect the way in which the MTB interacts with the path.
The plot of the carcass is measured in TPI, an acronym for ” threads per inch “, or threads per inch (a parameter which can be found in the catalogs of covers for MTB) and can go from 60 TPI to much higher values. In some carcasses, TPI there may be different in the sides and under the tread.
In principle, cross-country and marathon you prefer carcasses with around 120 TPI, thinner, more flexible, while for the most demanding applications such as all-mountain enduro or you go on carcasses from 60 TPI, wire bigger tires and more robust. Other differences between the various carcasses are the thickness, single or multiple, ie the presence of one or more layers of fibers, and the use of the tire with or without inner tube (tubeless). The carcasses with multi-thickness are generally more robust, but also heavier than those with single thickness.
The shoulder.
The side of the cover that goes from the rim to the tread shoulder (or hip). The shoulder should be able to promote the stability of the MTB when negotiating curves, but must also withstand the stresses to avoid pinching of the air chambers (with the risk of drilling). It has a pinching when the shoulder of the cover bends, due to the impact with an obstacle, squeezing the walls of the air chamber. With proper tire pressure and reinforced shoulders you can minimize this problem. The shoulder is reinforced by adding more resistant materials, such as, for example, Kevlar fiber.
The bead.
The heel is the part of the cover that will be fitted into the circle, thus locking in a position the whole cover. The material which is made of the heel may be different from the rest of the cover. The circle content in the heel promotes the inclusion of coverage in the circle, there are folding bead (Kevlar) and circles rigid (steel). The rigid solution promotes better adhesion of the cover to the rim, but has a higher weight.
The tread and plugs.
On the tread of MTB, you immediately notice the characteristic presence of the blocks in relief, divided into three bands along the tire: the middle and the two sides. Tessellation central acts on the ground during pedaling and braking and has the purpose of avoiding skidding of the tires, so it is crucial for both the smoothness of the tire for both the grip on the ground (the grip).
The changes concern the form and arrangement of the blocks on the tread, but also the compound with which they are made. In principle, soft compound ensures a superior grip, better absorb impacts with obstacles along the path (the impact is cushioned by the deformation of the tire, and only a small part is transmitted to the bike), but are less smooth and suffer from more wear. As regards the choice, in general on the catalogs are the types of competitions, routes and land for which a given tire is better prepared.
Tubeless tires or inner tubes?
Another difference to keep in mind when it comes to MTB tires is between shell with tube and tubeless tires. The tubeless tires (also referred to by the acronym FSO, Universal Standard for Tubeless Universal Standard for Tubeless) require special rims able to house them properly, while the shells with the air chamber are the traditional solution, in which the tire has the outside that encloses and protects the inside the air chamber. There is no perfect solution: both have advantages and disadvantages. The tubes tend to be burned for more frequently, but are easier to repair or replace than the tubeless tires instead owe their success to being much more durable and able to maintain the pressure for a long time even in the case drilling.
The measurements of the covers for MTB.
The measurements of the covers are generally shown with two values in inches. The first indicates the outer diameter, and the second indicates the width, for example. 26×2 indicates a rubber with a diameter of 26 inches and a width of 2 inches. It was subsequently created another standard (ETRTO), in which the first digit indicates the width of the tire (in millimeters), and the second indicates the rim diameter in mm (measured at the point of contact of the heels of the tire in the circle).
In catalogs of sale can be found both measures, for example, ” 26×2.00 (52-559) “, in this case the width of the tire is 52 mm, mounted on a circle with a diameter of 559 mm. The diameters suitable for hedges are those of the three available standards for the wheels of the bike, ie, 26 ” , 27.5 ” and 29 “, while the width can vary greatly, from just over 1 inch to more than 2 inches. Simplifying extreme, one can say that covers are narrower lighter and more flowing, while the covers allow wider use of lower pressures facing obstacles more easily.
The tire pressure.
Lower pressures of inflation of the cover allow you to have a better grip. With the solutions tubeless you can take lower pressures than possible with air chambers and is an important possibility, because the tire pressure is a crucial variable for the behavior of the bike. The decision about the best pressure to use is influenced by many parameters ranging from the type of tires on the driving style, the type of discipline MTB type bike, the terrain, the weather conditions.
Only experience can guide us in choosing the best pressure for our next release. To get started, you can still refer to different tables available on the Web, and then gradually adjust the pressure according to your preferences.
