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What bike wheel size do I need?

bike wheel sizes 1120x400 1

Hardly any other bike part is available in more sizes, widths and designs than the wheel. On the positive side, every cyclist will find exactly the wheel size that fits their individual riding style perfectly, but on the negative side, this variety leads to some confusion. Whether you need a 12 inch or a 29 inch wheel, Fatbike or Plus wheels and which rim is suitable for which purpose, you can find all information in our detailed wheel guide.

General Information about Bike Wheel Sizes

The confusion often begins with the concept of the impeller, since this does not only mean the rim, but also the spokes, the spoke nipples and the hub. The size of the wheels, however, basically only refer to the rim. Their diameter is usually specified either in inches or using the ETRTO standard. The latter is made up of the rim diameter and the inside width of the rim. A 26” rim with, for example, 29 mm inner width would therefore be labeled with the ETRTO 559 x 29.

With the help of these dimensions, the right wheel can be selected, because not every wheel width and size is compatible with every rim size (see section Bike Wheel Size). It can already be seen here that the wheel and rim system is extremely complex, also because different wheel widths have different properties in regards to rolling resistance, traction and steering precision. Ultimately, the decisions made on the wheel therefore have a significant impact on the riding characteristics of a bicycle.

The Different Bike Wheel Sizes

The following section explains all common wheel sizes as well as their advantages and disadvantages.

12"-18" Wheels

These very small wheels are particularly common on children’s bicycles in order to do justice to the smaller height of children. We give the following recommendations:

  • from 95-100 cm: 12 inches
  • from 100-105 cm: 14 inches
  • from 105-110 cm: 16 inches
  • from 110-120 cm: 18 inches

But folding bicycles also benefit from the small dimensions of the 16-inch bikes. When folded, the wheels are usually the most space-consuming part. By using 16 inch wheels, the pack size and weight are naturally reduced, while mobility and portability are improved. The smaller wheels are also more stable.

20" Wheels

As with 16 inches, the same applies to 20 inches that smaller wheels are more stable and weigh less. That is why 20 inches is the most common size for folding bikes and is often found on the front of cargo bikes (26 inches on the rear). 20-inch wheels combine the perfect mix of low weight and good rolling properties. They also allow a small pack size, which is why they can be easily transported by bus, train or car.

But children between 115 cm and 120 cm tall also benefit from this wheel size. The good rolling characteristics make it much easier to keep up with the bikes for adults. This makes the first longer tours with the family possible, although the overhang height of these bicycles remains low.

BMX bikes are a slightly more special types of bikes, which also often use 20 inches. Here are mainly wide wheels used on small rims, which provide increased grip and better stability when jumping and doing tricks.

24" Wheels

Sporty folding bikes like to use 24 inch wheels, because the larger wheel diameter allows higher speeds. For this, the somewhat increased pack size is gladly accepted.

But also kid bikes, for riders with a height between 135 cm and 165 cm, are suitably equipped with 24 inch wheels. Here, as with 12-20 inches, the wheels have to grow with the frame and body size to enable a meaningful geometry. This wheel size can also be found on so-called mini bikes or on special designs for smaller adults, since a suitable protruding height is crucial for a comfortable bike.

26" Wheels

A few years ago, 26 inches was still the dominant wheel size in the mountain bike sector. In the meantime, these wheels are almost only found on downhill bikes, fat bikes and entry-level bikes. Also in the city and trekking area is often set to 26 inches, because the parts are quite cheap and allow small frame sizes. An important point, especially for beginners.

However, the longstanding dominance of 26-inch wheels is no coincidence: thanks to a good balance of stability, rolling properties and acceleration, the wheels fit many riding styles. There are still a large number of different wheels and new developments in this area. In the mountain bike sector, however, newly developed components and wheels are often only available in 27.5 or 29 inches.

27.5" Wheels

With 27.5 inch (or 650B) wheels, the good balance of the 26 inch wheels should be further optimized. The almost ubiquitous distribution of this wheel size and its success in competitions prove this development right. In fact, the size is also closer to 26 inches than the name suggests. With a diameter of 584 mm, 27.5 inches is closer to 26 inches (559 mm) than to 29 inches (622 mm). Thus, the positive properties such as the stability and acceleration, are included as with the 26 inches wheels, while slightly better rolling properties are obtained. This benefits mountain bike hardtails and fullys, urban, city and trekking bikes, but also road bikes.

However, the full strengths are only played out on winding single trails, which is why 27.5 inches has now become the standard in the MTB world. This impeller standard is therefore also very future-proof, as all new developments will appear for 27.5 inches, even in the coming years.

28" Wheels

28 inch wheels offer an optimal balance between rolling behavior and handling of the bike. This format is widespread and has become the standard when it comes to high speeds and smooth running. The wheel size is therefore used on road bikes as well as on everyday trekking or city bikes.

In contrast to 26 inches, there is also a wide selection of wheels that are similar in width to road bike wheels, but offer a little more grip and puncture resistance. This makes them the ideal wheels for the city. There are also many differently wide rims and widespread, inexpensive spare parts.

29" Wheels

As if the names of wheels weren’t confusing enough, you can’t rely on the name for the 29 inch anymore. In fact, these are 28-inch rims that measure around 29 inches including a large-volume mountain bike wheels. As confusing as the name is, the properties are so obvious: 29 inch wheels are ideal for lightning-fast cross country and marathon bicycles, because the large wheel diameter enables an enormous amount of propulsion. Due to the inertia, they can be accelerated somewhat poorly, but this is accepted for the extremely smooth running and the better rollover behavior.

Inexperienced drivers in particular benefit from these properties, as it is easier to cope with minor bumps in the way, such as rubble, stones and roots. But racers also win the crucial seconds, as evidenced by the dominance of 29-inch wheels in the XC World Cup.

In the meantime, highly developed manufacturing processes for rims and spokes also enable the use of 29 inch wheels on trail bikes. Stability was a problem here for a long time. 29″ wheels are extremely flexible, whereby you always have to make sure that the wheels fit your own size. Small drivers use 27.5 inches better.

General Information about Bike Wheels

The choice of wheels not only changes the grip and rolling resistance, but also the real external dimensions of the wheel, as well as its damping and steering accuracy. Thus, the driving characteristics do not only depend on the chosen wheel size, but also on its dimensions. Here, however, the number of different sizes is almost as confusing as with the wheels, which is why the following sections provide an overview of common wheel dimensions and their advantages and disadvantages.

Bike Wheel Sizes

As mentioned at the beginning, the rim size must always match the wheel size. Here it is not only important that the rim diameter matches the diameter of the wheel, but also that the width is compatible with the rim width. For this purpose, wheels are also awarded an ETRTO standard, which specifies the outside width of the tires in addition to the diameter. This table can be used to check which tire-rim combination fits:

Rim Width (mm)Wheel Width (mm)               
18202325283235374044475054576062
13✔️✔️✔️✔️
15✔️✔️✔️✔️
17✔️✔️✔️✔️✔️✔️✔️✔️✔️
19✔️✔️✔️✔️✔️✔️✔️✔️✔️✔️✔️✔️
21✔️✔️✔️✔️✔️✔️✔️✔️✔️✔️
23✔️✔️✔️✔️✔️✔️✔️✔️✔️
25✔️✔️✔️✔️✔️✔️✔️
27✔️✔️✔️✔️✔️✔️
29✔️✔️✔️✔️

 

As a rule of thumb, however, the wider the tire, the wider the required rim. It is important not to rely on the tire manufacturers’ customs information, but to actually use the ETRTO standard. Different manufacturers measure their tires based on different criteria, which can lead to the same customs data but different ETRTO data for two different tires. For example, a Continental 27.5 inch tire with 2.4 inches is 60 mm wide according to ETRTO, while a swallow with the same circumference is already 60 mm wide at 2.35 inches. One of the reasons for this is that the tire width grows with the width of the rim. The same tire is therefore different in width on two rims of different widths. So be careful here. However, most mountain bike rims should not cause any problems between 2 inch and 2.4 inch tire widths. The same applies to the most common road bike rims and tires. With the increasing number of plus formats and fat bikes, it is extremely important to use suitable rims.

2"-2.3" Wheels (50-60mm)

Standard mountain bike wheels move in a frame from 50 to 60 mm (2.0 to 2.3 inches) wide. It applies that the descent orientation increases with the increasing width. This is logical inasmuch as wide wheels are usually accompanied by more aggressive treads and there is more contact area available. On the other hand, narrow, slightly profiled wheels roll more easily. So if you want to drive cross country or marathon, you tend to use 50 mm wheels, if you prefer to go downhill, you can use a coarse 60 mm wheel.

Most standard mountain bike rims can safely accommodate both wheels, but a wide rim supports solid wheels better, which increases damping and therefore performance. For example, when using 60 mm wide wheels, rims with at least 25 mm inner width have prevailed. However, some drivers use rims up to 40 mm wide in order to generate as much contact area and therefore grip as possible.

Plus-Size Wheels

Plus wheels are currently available for 27.5 inch and 29 inch mountain bike wheels. This format does not exist for 26-inch wheels, as virtually no 26-inch frames were developed that would offer enough space in the rear triangle to accommodate the wheels, which are up to 2.7 inches (71 mm) wide. Rims that are suitable for plus wheels are usually already marked this way.

In general, it can be said that the rims should have an inner width of at least 35 mm to ensure a safe and sensible fit. A 27.5+ like the Scott Spark 720 Plus is the right choice for downhill-oriented drivers, while a 29+ makes those who want to drive uphill and downhill happy.

The advantages of the large-volume wheels are the increased damping. While suspension forks and sprung rear triangles always have a certain breakaway torque that cannot be overcome by very slight bumps, some shocks are transmitted to the driver without suspension. This is usually done by means of fine vibrations, which in particular cause the muscles in the arms to wheel quickly and therefore cause forced breaks on the trail.

Plus wheels absorb these vibrations and thus enable extended trail fun. This is made possible on the one hand by the additional material, but also by the lower air pressure that can be driven by the increased volume. In contrast to “normal” wheels, which require more air pressure, more is damped. On the negative side, a plus wheel steers a little more spongy due to the low air pressure, but this effect is often exchanged for the advantages mentioned.

Fatbike

The Fatbike takes the idea of plus formats to the extreme. Wheels up to 5 inches wide ensure so much cushioning that many fat bikes do without spring elements and are delivered with a rigid fork. Of course, this increases the spongy feeling that already occurs with the plus formats, but you gain extremely much traction. In addition, fat bikes allow you to ride on otherwise unthinkable surfaces such as sand or snow, as they do not sink due to the large-volume wheels.

It is therefore not surprising that the first fat bikes were intended as expedition bikes for rough terrain. So if you want to go on a discovery tour, you are very well advised with the monstrous wheels. In order to fit the wheels sensibly, at least one rim with an inner width of 80 mm should be selected (for 5 inch wheels better 100 mm and more).

A secure fit due to sufficiently wide rims is particularly important for fat bikes, since these are held less by the air pressure (usually only 0.6-0.8 bar) in the rim bed than by the shape of the rim. If the rims are too narrow, the wheel tends to jump off the rim, which can lead to dangerous falls.

Since the thick wheels apply properly, fat bike wheels are usually designed for 26 inches (559 mm), although the effective radius of the wheel and wheel is still very large. This means that a fat bike rolls just as well as a 29 inch wheel or 27.5+ bike, although of course the rolling resistance is higher.