Many cyclists, when choosing a new bike, primarily focus on the frame and fork, considering them key elements. They are interested in the frame material, manufacturing technologies, fork type, travel, adjustments, and lockout presence. Other components often remain without proper attention, as they are considered less important for the bike’s main characteristics.

However, this approach is only partially correct. Undoubtedly, the frame and fork are the foundation of the bicycle, which determine handling, comfort, durability, and, consequently, riding pleasure. But they represent only two of the three key elements of a bicycle. The third crucial component is the wheels. They provide contact with the road, are the first to absorb impacts from surface irregularities, then transferring them to the suspension and frame. Weighing about two kilograms each, wheels carry the weight of both the bicycle and the cyclist. Moreover, wheels directly affect acceleration speed and its maintenance, stability in turns, and precision of response when turning the handlebars.

Reasons for Rim Replacement

Usually, a cyclist faces the choice of a rim infrequently – when buying a new bicycle or replacing a wheel. Typically, the rim is acquired with the bicycle and used until serious damage or complete wheel replacement. Here are some reasons for rim replacement:

• Frequent occurrence of wheel “eights,” which may indicate problems in rim construction, material, or riding style
• Thinning of material due to intensive use of rim brakes, especially modern v-brakes, which significantly wear out brake tracks

Types of Rims

Single-wall

Single-wall rims are the most affordable but least durable. Their lifespan is difficult to predict as it strongly depends on riding style. With aggressive riding and long trips, such rims can break several times per season. However, for calm riding on smooth roads, they are quite suitable. They are installed on recreational and city bicycles not intended for high loads. Single-wall profiles made of steel strips are often found on inexpensive bicycles of little-known brands. This clearly demonstrates manufacturers’ approach to using the cheapest and heaviest materials. It’s not surprising that such bicycles often require repairs even with normal use in the city.

Double-wall

Double or double-wall rims represent a completely different level of quality. They belong to a higher price category due to their strength and durability. Interestingly, the weight of double models can be even lower than that of single-wall ones. Such rims are used on cross-country and downhill bicycles. If necessary, strength can be further increased by increasing the rim height, which reduces the likelihood of “eights” forming. For manufacturing such structures, aluminum double-wall profile is most often used. This invention became a significant step forward in creating rigid rims capable of withstanding serious loads, bad roads, and high working stress. The strongest and most expensive are triple rims made of triple-wall profile, but they are rare due to the lack of real need for their use. Double structures cope excellently with off-road and high loads.

Special Elements

In addition to the main circumference and structure, the rim has holes for spokes and nipples, as well as grooves for tire mounting. These small elements can become vulnerable spots where even a minor defect can lead to damage to the entire rim. To strengthen the holes, eyelets are used – strong metal inserts that fix the spoke in the hole. These reinforcing elements, initially appearing as DIY repair solutions, have now become standard for above-average rims.

Materials

The choice of materials for rims is surprisingly limited:

• Aluminum – the undisputed leader. Inexpensive, strong, and versatile, it represents an optimal compromise between all qualities and is used in most rim models.
• Steel – a legacy of the past century. Reliable in terms of wear resistance and hardness, but very heavy steel rims have almost disappeared from the market. Finding a double steel rim now is quite difficult.
• Carbon – modern technologies do not stand still, and carbon rims appear not only on tracks but also in urban conditions and on highways. They combine lightness and hardness but have a very high price.
• “Proprietary” alloys – various combinations of metals, allegedly possessing unique properties. Usually not worthy of special attention due to the predominantly marketing component. In practice, they do not show significant advantages over aluminum.

In addition to the main material, anodizing is sometimes used in rim manufacturing. Such rims are easily recognizable by their characteristic black surface. Additional galvanization increases the strength of a regular aluminum rim by several tens of percent. This coating is often used on rear rims with v-brake brakes, which require additional strength during braking.

Manufacturers

• Alex Rims – OEM manufacturer supplying rims to most well-known bicycle brands.
• Mach – French manufacturer specializing in road rims.
• DT Swiss – Scandinavian premium manufacturer.
• Mavic – versatile and reliable rim manufacturer.

Measurements

Let’s consider the main characteristics of the rim:

Length

The main parameter is the “bead seat diameter” or fitting size, which determines the wheel size along the circumference. Three systems are used for its designation:

• ISO – the actual rim diameter in millimeters. This is the standard and basis for comparison with other measurement systems.
• Inch size is recorded in the format 20″x2.0, where 20 is the length in inches, and 2.0 is the width. Fractional numbers can be written either with a fraction line or in decimal form, which can cause confusion.
• French size, like ISO, denotes the rim diameter but is supplemented by the tire width in the form of letter designations from A to D (A – narrow, D – wide).

It’s important to note that “Soviet” sizes do not coincide with modern Western ones, even with identical markings.

Width

Although length affects riding comfort, the main influence on characteristics is exerted by tire width. It affects the effort expended, shock-absorbing properties when performing tricks, and weight. Matching a rim to the desired tire is not easy due to the complexity of the construction and constant loads, including impact loads. Even minimal discrepancies in width can lead to damage to both the tire and the rim.

Rim width is practically standardized for each riding style and is indicated in millimeters:

• Up to 15 mm – for trekking, road, and high-speed riding.
• 17 mm – for hybrids and modern cross-country, where alloy hardness is especially important.
• 19 mm – for standard mountain bikes.
• 21 mm – for basic tricks and bicycle touring.
• 23 mm – for extreme cycling sports.

Spoke Characteristics

To work with spokes, you need to know several additional parameters and terms:

• Effective rim diameter (ERD) – the effective diameter of the rim, measured along the spokes (from the end of one to the end of the opposite).
• Offset of spoke bed (OSB) – the offset of holes (transverse). It is not equal to zero only in rare asymmetrical models.
• Number of spokes – for standard 24″-26″ rims, this is usually 28, 32, or 36 holes. For 29ers (29 inches), the standard has not yet been established.