Comparison Maxxis Ikon 27.5x2.2 vs Maxxis Crossmark 26x2.1

The nominal size of a tire, expressed in inches or millimeters.

When choosing according to this parameter, you need to take into account that the characteristics usually indicate not the inner, but the outer size of the tire. Thus, the overall performance properties of the product depend on the nominal size in inches, and not its compatibility with a specific rim (it is better to check compatibility according to the ERTRO standard, see below).

In general, larger wheels are good for going “far, long and at a steady speed,” while a small size provides good acceleration dynamics and is more convenient for trick riding. And in many types of bicycles there are traditional wheel sizes, optimally selected according to a number of parameters specifically for a given application. So, for a mountain bike (MTB) you will most likely need tires with a landing size of 26", for a road bike - 28", for a BMX - 20". However, there are exceptions, so the specific landing size must be checked before purchasing Yes, and deviations from the “native” external dimensions are quite acceptable - for example, 29" “Niner” tires usually coincide with 28-inch tires in terms of seat size.

Note that the main dimensions of a product can be indicated in different ways: two numbers (for exampl...e, 26" x 3.0"), three (28" x 1 1/4" x 1 3/4"), or even an alphanumeric index (700x40C). However, in any case, the first number indicates the outer size. In the last example, this size is indicated in millimeters; 700 mm in this case is equivalent to 28". If only the nominal dimensions are known for a tire and the ETRTO standard is not specified, it is best to assume that identical markings mean identical dimensions, and select a replacement model with the same numbers as the previous tires. As a last resort, if you need to select a product labeled in a different format, you can use special techniques to determine the actual dimensions; Such techniques can be found in special sources.

The nominal width of a tyre, in fact, is its width with a normally inflated wheel. Approximately this parameter is expressed in inches, more precisely - in millimeters. The latter option is used in bicycle tyres marked according to the “French size” (see the corresponding paragraph).

As well as the fit size (see "ETRTO Standard"), this indicator determines the compatibility of a tyre with a particular rim. However, if the size must exactly match the size of the rim, then in the case of the width, the selection rules are somewhat different. It doesn't have to exactly match the inside width of the rim - a tyre that is 1.5 to 2 times as wide is considered the best option. Up to 2.5 times is allowed, but care must be taken here: a tyre that is too wide on a narrow rim will behave worse in corners and may break off the rim. Also, excessive width impairs handling at low speed and with a pressure drop (even a small one), accelerates sidewall wear. In turn, a tyre that is too narrow is more likely to puncture and damage the rim due to abnormal loads on it.

Recall that if the marking of the tyre matches the marking of the standard tyres of the bicycle, it is guaranteed to fit it. This is true for width as well. At the same time, there are tables that allow you to determine what "non-native" tyre width is suitable for a particular rim.

The main dimensions of the tyre are in accordance with the ETRTO standard (the name "ISO standard" is also found). Indicated in millimetres, while the first digit corresponds to the width of the tyre, the second to the inner diameter.

The variety of markings used for bicycle tyres (including french size 650x23C, 650x25C, 650x28C, 650x35C, 650x43C, 650x48C, 650x54C, 700x20C, 700x22C, 700x23C, 700x25C, 700x26C, 700x28C, 700x30C, 700x31C, 700x32C, 700x33C, 700x34C, 700x35C, 700x38C, 700x40C, 700x42C, 700x43C, 700x45C, 700x47C, 700x50C...) at one time created many problems for both users and specialists. Moreover, in most cases, inches were used for marking, and this is a less accurate unit of measurement than millimetres. Moreover, formally identical sizes with different designation formats often differed in fact — for example, 1.75 "and 1 3/4" inches could correspond to different actual sizes in millimetres. Also, manufacturers most often indicated in the characteristics the outer diameter of the tyre, and not the inner one, and without actual fitting it was far from always possible to choose a product to fit the rim size.

To remedy the situation, the ETRTO (ISO) standard was developed. Dimensions according to this standard are perhaps the most important parameter for selecting a bicycle tyre. First, ETRTO covers the two main characteristics that determine rim compatibility — bore diameter and width. See above for the meaning of width; and the tyre and rim must match in terms of the rim diameter — otherwise the installation will be simply impossible, no matter how perfect the other characteristics of the “rubber” may be. Secondly, ETRTO uses a designation in millimetres, which allows you to choose the tyre size with maximum accuracy.

There are tables that allow you to translate some branded "inch" markings into ETRTO values; such tables can be found in special sources. However, the need for such data rarely arises: most modern manufacturers, along with branding, also use the ETRTO standard.

The carcass density of the tyre in threads per inch (Ends Per Inch or Threads Per Inch).

The material of a bicycle tyre is composite in composition, it includes a beading cable (see below), a frame (cord) made of synthetic fabric, and rubber itself (compound). The density of the frame determines primarily the softness of the product; dynamics, rolling, cross-country ability and a tendency to crush when hitting obstacles and other heavy loads depend on this. So, a soft cord is better suited for driving over rough terrain, including on difficult surfaces like sand or gravel: it provides a larger contact patch, crumple well on small bumps and allows you not to lose speed when hitting a small obstacle like a pit, tree root, etc. Yes, and it shakes on such tyres less than on hard ones. On the other hand, they hold speed and roll worse, and also have an increased likelihood of punctures in certain situations: for example, a sharp stone can dent the tyre to the very rim and pierce the chamber.

Hard tyres, in turn, are distinguished by good dynamics: it is easier for them to pick up speed and maintain it. Yes, and when hitting the same sharp stone, the probability of a puncture will be much lower. On the other hand, the slightest obstacle on the road when driving on such tyres will lead to a noticeable loss of speed, and on uneven surfaces the bike will be subject to strong shaking. In addition, from a certain value (120 EPI and above), an increase in the dens...ity of the carcass does not increase, but a decrease in reliability: a high density of threads leads to a decrease in their thickness and, accordingly, strength.

Also recall that the actual stiffness of the wheel will depend not only on the carcass, but also on the pressure in the tyre. So in some situations, the features of the frame can be completely compensated for by selecting the appropriate pressure.

If we talk about specific numbers, then tyres with a cord density of up to 60 EPI (TPI) can be classified as soft, up to 90 TPI — as medium, up to 120 — as hard, and a value of more than 120 EPI (TPI) corresponds to high rigidity. With the above in mind, soft tyres are better suited for rough terrain and stunt riding, while hard tyres are better for high-speed driving on flat roads. More detailed recommendations on this matter can be found in special sources.

The material of the bead wires used in the tyre.

A beading cable is a rigid cable passed along the edge of the tyre (along that part of it that is in direct contact with the rim. It allows the tyre to maintain its shape and provides it with a snug fit to the rim. Such an element can be made from different materials:

— Steel. A steel wire beading cable is a classic and most common option in modern models. This design is quite practical and at the same time inexpensive. It does not have some of the advantages of Kevlar (see below), but in most cases this is not critical.

— Kevlar. Kevlar fibre is lighter than steel wire, resulting in an average weight gain of about 100 grams per tyre. It is this option, for a number of reasons, that is considered optimal for tubeless models (see below). In addition, it allows you to fold the tyre very compactly (literally “flatten” it) without losing performance. Therefore, models with such cables are sometimes also called "folding". However, they are much more expensive than tyres with traditional materials.

The total weight of the tyre.

This indicator affects the overall weight of the bike, but this influence is so insignificant that in most cases it can be neglected — especially since the difference between tyres similar in size and use can be some tens of grams, or even grams. In fact, paying attention to weight makes sense mainly when used in professional racing, where the struggle sometimes goes for tenths of a second — and, accordingly, every extra gram can be decisive. If tyres are bought for simpler use — for example, amateur "rides" on roads or even cross-country — this parameter can not be given much attention.