The bike is maintained thanks to you. In this guide, you will find useful information for those who are looking for new rings or simply those interested in learning more about the subject. In these best mountain bikes under 500, you will get a strong variation. Now, let’s get right into the topic of bicycle rims, but before going into detail, we must clarify that it is possible that in your country, this component is called differently. In what refers to this guide, we will refer to the ring or rim as the circular piece, generally made of aluminum, carbon fiber, steel, or other material, which is connected to the ground through the spokes or spokes.
Measurements of a bicycle ring
What size rim does my bike need? This is a question that, with so many measurements and different systems for its measurement, can lead to confusion.
Traditionally, two systems have been used to size the tire (tire) and the rim of a bicycle. On the one hand, there is the French System with units of measure expressed in millimeters (mm): 700; 700A; 700B; 700 x 23; 700 x 25, etc.
On the other, the English System, with its units of measurement expressed in inches (in): 28 x 1¼; 28 x 1⅜; 28 x 1½, etc. To make it even more complex, the latter can be expressed in decimal or infractions, and they are not interchangeable. That is, the width of a 26 x 1 ¾ tire or tire is not equal to that of one marked 26 x 1.75.
In more recent times and to standardize the measures, these were standardized under the ETRTO System or European Technical Organization for Tires and Wheels, ratified by the International Organization for Standardization ( ISO 5775 ).
The ETRTO system provides a better match between tire size and rim size. For example, we can now be certain that a tire marked 42 x 650b (42 – 584) will be able to mount on a rim marked with an effective diameter of 584 mm.
The system is not yet 100% accurate, as there may still be slight differences in width between the different rim and tire/tire combinations. So now, the only thing that affects is its adjustment and how easy or difficult it is to mount the tire on the rim. In the case of tubeless rims, this issue must be taken more seriously since the rim and tire have to be as tight as possible, so it is always recommended to test.
Bicycle Rim Effective Diameter
The Effective Rim Diameter (ERD) or effective rim diameter is the measure of the diameter on which the ends of the rest of the spoke.
It can be measured as follows:
- Insert two spokes through holes exactly opposite each other on edge (count the holes to be sure).
- Screw the nipples onto the spokes.
- Tighten them tightly and measure the distance to the edge of the nipples, where the spokes disappear into them. Do this at various points around the edge and average the measurements.
- Measure the length of a nipple and add twice (once for each nipple).
- The result is the effective edge diameter (ERD). Therefore, D = A + 2B.
- The inner width of the bicycle rim
Rim Internal Width
The Inner Rim Width is the measurement in millimeters that we take between the inner edges (flanges) of the rim walls. This measurement will have a direct relationship with the width of the tires that you can place on the rim, or the ideal combination between the width of the tire and that of the bicycle rim in terms of rolling efficiency, comfort, air volume, and the “true” width of the tire.
It can be measured with a vernier caliper or, using a tape measure. Using the tape measure, you will need to make sure that you are positioning it properly on the inner edges of the rim to obtain an accurate measurement.
It is important not to confuse this measurement with the external width, which is the measurement in millimeters that we take at the height of the braking tracks. This measure will mainly influence the appearance of the rim but also the aerodynamics of the rim-tire system. It has no bearing on comfort, rolling efficiency, or the shape of the tire.
Common materials of bicycle rings
- Aluminum alloy
- Carbon fiber
Although it has been the most used material since its inception, steel is currently used in low-end wheels. The different aluminum alloys and carbon fiber are used in medium to high ranges.
The best choice for the material of your wheels will depend on the performance you are looking for, in conjunction with the tire you will use. Another determining factor is the resistance you are looking for because, in addition to the material, the number of rays you will need will be an important factor.
Bicycle rings for different types of brakes
Currently, there are different brake systems for bicycles. And the rims of the bicycle must be compatible with the braking system that is going to be used. In general, it is important to consider whether the bicycle on which we are going to mount the rings uses ring brakes or disc brakes.
Rims that are designed for use with rim brakes have a brake track on their sides. This track is where the brake shoes will friction.
For their part, rims that are designed to be used with a disc brake do not have such a track and cannot be used with any type of rim brake.
Common rim measurements on current bikes
The exponential growth in the bicycle industry has led to the creation of different sizes of rings for different types of bicycles. From children’s bicycles to the most common and even specialized ones. In this guide, we will limit ourselves to talking about those that are most common in the current market and, only in bicycles for adults.
Mountain bike hoops
Currently, the vast world of mountain biking uses rims with diameters: 29″ (622), 27.5″ (584), and less and less frequently 26″ (559). Common internal widths range from 19 – 40mm, depending on the MTB discipline and performance sought.
26-inch rims were the standard in mountain biking for years. However, more recent trends led to testing larger diameter wheels capable of rolling more easily on stones and logs. The first increase was towards 27.5 rims (584), a measure that is also common on gravel bikes. This type of rim opened the doors to the inclusion of wider tires with more buoyancy of up to 3″, known as 27.5 Plus + or fatty tires.
The trend continued and then 29″ (622) hoops were adopted. Today, the industry has brought more variety to mountain bikers and they can select the rim/tire combination needed for each type of discipline and performance. As an extreme case, we can find fat bike bicycles where the thickness of the tire can range from 40 to 100 mm.
Example of mountain hoops – WTB KOM
The WTB KOMs are available in both 27.5″ (584) and 29″ (622) and with internal widths from 25 to 45mm. They are made of aluminum alloy and designed for use with disc brakes. USE: Cross-Country / Trail / Gravel
For its part, road cycling has seen how the 700C (622) wheels were displacing the traditional 27″ (630) rims, becoming a constant in most of its frames. The 650C (571mm) rims have been used to equip smaller frames, listing widths ranging from 13 to 25mm.
In keeping with the new trend in gravel bikes, the use of wider rims has also become popular, making room for those with 650B (584mm) rims. Its smaller diameter offers the possibility of using wide tires that can go from 34mm to 50mm to cover the most difficult terrain.
Example of road rings – DT SWISS R460
The DT SWISS R460s are available in 700c (622) tread and 18mm internal width. These are rims made of aluminum alloy and their design is for use with rim brakes. Use: road cycling / urban cycling
Likewise, the 700C ring (622) has been widely used in hybrid bikes and city bikes. For its part, and within the group of urban bicycles are the practical folding bicycles. These small wheel bikes usually use 20″ (406) rims and some others use 16″ (349).
Example of the hoop for urban use – DT SWISS
DT SWISS TK540 rims are 700c (622) and 18.2mm internal width. This is a 36 hole rim, which makes it ideal for those who need more resistance on the wheel. Whether in the city or when traveling by bike. Use: Cycling / urban
To recap, the two measurements that will help you select a rim for your bike. And will be to determine the effective diameter and internal width. On the other hand, you should consider the tires you plan to use. And if you go for wide rims, make sure you have enough space in the frame and fork.
Important note: As mentioned before, the ETRTO system is not perfect. So it is recommended to test the clearance between the tire and the bicycle rim.
Rim and tire width combinations
When talking about the combination between tire and rim. We could say that as long as their diameters are the same (in the ETRTO system). You could put any width of the rim on any rim.
Riding a tire that is too wide for a given rim. Or on the contrary, one that is too narrow on a wide rim could cause problems. In such a case, the least that could happen is that the wear of the cover accelerates. And, in extreme cases, you could suffer an accident. Either due to deformation of the tire when cornering or even coming off the rim completely.
To be certain, it is best to consult the particular specifications of the rims. And the rim you want to combine. And again, this highlights the importance of testing.