Bike Wheel Sizes Explained: A Guide for Beginners

Budget isn’t the only thing that matters when getting yourself a bike. The right wheel size makes all the difference between a comfortable ride and an expensive mistake.

Bike wheels come in different sizes, such as 16 in. (40.6 cm), 20 in. (50.8 cm), 24 in. (61 cm), 26 in. (66 cm), 27 in. (68.6 cm), 27.5 in. (69.9 cm), 29 in. (73.7 cm), and 32 in. (81.3 cm). The right wheel size for an adult bike is based on your frame size, bike type, and your required frame size.

Let’s explore the different types of wheel sizes and what each size offers. Further on, I’ll discuss how you can choose the best wheel size for you.

How Wheel Size Are Measured

While each bike wheel size is measured in inches, these wheels also use a measurement known as ISO.

ISO 5775 is an international standard through which all bike wheels and rims are measured. The ISO of a bike wheel measures the diameter of the bike’s rim bead in millimeters. For example, for a 16-inch (40.6 cm) bike wheel, the ISO will measure 305 mm (12 in.).

You can also use ISO measurements to refer to each bike size, as these measurements are commonly referred to in the biking industry.

What Are the Different Bike Wheel Sizes?

16” (40.6 cm) Wheels (ISO 305 MM)

16-inch (40.6 cm) wheels are commonly used in the largest children’s bikes. Otherwise, this wheel size is considered the smallest size for adult bikes. For people with shorter legs or height, the 16-inch (40.6 cm) wheel works well. However, it comes down to whether you’re comfortable sitting on the bike.

These wheels are commonly used in compact foldable bikes. However, you can expect a decrease in quality as they’re smaller in size. These wheels are shorter, so they don’t fare well when traveling on rough roads or bumps. You can expect to feel some small rocks and debris flying as you ride, and you might also get stuck in potholes, so it’s important to stay vigilant. 

Adult bikes with 16-inch (40.6 cm) wheels are also considerably harder to maneuver on hills since they require a larger gear ratio to turn. If you need a smaller wheel bike, you’ll want to keep the 16-inch (40.6 cm) wheel bike for general riding rather than for your trailblazing adventures.

20” (50.8 cm) Wheels (ISO 406 MM)

The 20-inch (50.8 cm) wheels are standard for BMX bikes. You’ll also find that most folding bikes also sport these small wheels, especially those designed for rougher use.

Unlike the 16-inch (40.6 cm) wheel, the 20-inch (50.8 cm) wheel is easier to maneuver. It travels well and makes biking easier for beginners. However, like the 16-inch (40.6 cm) wheel, these wheels undergo plenty of abuse from debris and rocks. 

These smaller wheels require a unique frame and a longer handlebar stem so that the rider can maintain an upright position. As a result, it becomes harder to steer the bike, which also leads to handling issues. If you’re a new rider, it’s best to skip the 20-inch (50.8 cm) wheel, just in case you can’t handle the more stiff frame.

20” (50.8 cm) Wheels (ISO 451 MM)

If you have a racing BMX or a classic shopping bike, you’ll come across a 20-inch (50.8 cm) wheel on them, too. However, these have an ISO rim of 451 mm.

Although the measurement is more than the 406 mm (16 in.) than the original 20-inch (50.8 cm) wheel has, this ISO 451 was initially called a 20-inch (50.8 cm) wheel. However, you’ll rarely find wheels with an ISO 451 anymore.

24” (61 cm) Wheels (ISO 507 MM)

24-inch (61 cm) wheels were relatively uncommon in the bike industry until fairly recently.

24-inch (61 cm) wheels were initially fitted in BMX cruiser bikes or junior mountain bikes. The frames had the same maneuverability and geometry as the 20-inch (50.8 cm) bikes. However, because of the slightly larger wheel size, this wheel became famous for mountain bikes.

As a result, many junior mountain bikes now sport the 24-inch (61 cm) wheel, which is becoming a norm in the industry.

Based on your preference, the 24-inch (61 cm) wheel might suit you well for a regular bike. However, you might want to delay any plans on getting a mountain bike until you’ve become well-accustomed to handling speed and control.

26” (66 cm) Wheels (ISO 559 MM)

The 26-inch (66 cm) wheel has remained a standard wheel size for most American bikes for a century, so you’ll find plenty of bikes with these wheels. Popularized by its use in mountain bikes, this size wheel is the only one wide enough to sustain the demands of rough roads and off-road biking.

As such, you’ll find that to this day, most high-performance bikes, including mountain bikes and folding bikes, use the 26-inch (66 cm) wheel. However, don’t be mistaken in thinking that the “26 inch” (66 cm) refers to the complete diameter of the wheel. Instead, it’s the tire’s outside diameter. As that’s the ISO of the 26-inch (66 cm) wheel comes down to 559 MM.

27” (68.6 cm) Wheels (ISO 630 MM)

The 27-inch (68.6 cm) bike wheel was a staple during the 1970s to 1980s before the more stable 26-inch (66 cm) wheel replaced it.

Although no longer in use, you’ll still find many homes with such wheels stored in garages and basements. Because these wheels are still used in bikes, companies still manufacture them, but they don’t encourage using this wheel size. If you have a vintage bike, it’s best if you keep your old bike stored safely away rather than risk using it.

Nevertheless, if you still want to ride it, your local bike shop will have to order you a 27” (68.6 cm) tire.

27.5” (69.9 cm) Wheel or 650b Wheel (ISO 584 MM)

Something you’ll get used to as you become familiar with biking terminology and components is the use of different names for essentially the same size wheels.

For example, the 27.5-inch (69.9 cm) wheel was initially called the 650b wheel. Unlike the 29” (69.9 cm) wheel, the 27.5-inch (69.9 cm) or 650b wheel had better stability on smaller road frames. These wheels could easily drive on gravel or roads and carve a path for similar wheel sizes to be introduced into mountain bike construction.

This was when the 650b wheel was changed into the 27.5” (69.9 cm) wheel because it could be used for off-road biking. The wheel offers greater advantages than the 26” (66 cm) wheel since it rolls off obstacles easily, allowing the rider to maintain momentum through rotational inertia. Plus, it can offer a better contact patch.

Because of its many advantages, the 27.5-inch (69.9 cm) wheel was also the first wheel used in the initial folding bike models worldwide.

29” (73.7 cm) Wheel or 700c (ISO 622 MM)

The 20-inch (50.8 cm) wheel is also called the 700c wheel and is the standard wheel for most modern road bikes. These bikes have an ISO of 622 MM. However, because the wheel has a complete outer diameter of 700MM, it’s referred to as the 700c wheel in international industries. This wheel comes equipped with multiple rim sizes, including the 700a, 700b, and 700c.

However, because the other wheel sizes have died out, the only remaining is the 622MM rim size, which comes equipped in the 700c wheel. This wheel is fitted in all bikes meant for narrow roads as well as folding bikes.

This wheel offers better performance and is a much better option if you want a well-rounded bike that’s durable and easy to transport. 

Alongside the 27.5-inch (68.6 cm) wheel, the 29-inch (73.7 cm) wheel is standard in the mountain biking world since riders can push their bikes to the limit without sacrificing maneuverability.

This wheel is also a better option for a high-performance mountain bike since the wider rim makes for wider tires. 

32” (81.3 cm) Wheel (ISO 686 MM) and 36” (91.4 cm) Wheel (ISO 787 MM)

The 32-inch (81.3 cm) wheel is uncommon but used for custom-built frames for tall riders. 

If you’re over 6’6” (198 cm) and need to find a bike that fits your stature, a bike shop will have no problem finding you a larger, custom-built bike. However, you won’t find one anywhere readily near you.

In other words, the 32” (81.3 cm) and the 36” (91.4 cm) wheels are monsters and are meant for larger people.

Are All Wheels and Tires the Same?

Wheels and tires aren’t the same. The word wheel can refer to any round object. However, a tire is something specific. Tires come in different types, are made of different qualities, and are classified into different categories.

Mainly, there are 4 types of tires:

  • Clinchers. They’re more commonly used for bikes, so you’ll generally find these in almost all utility bikes.
  • Folding bikes. These are similar to clinchers; only they have the quality that you can fold them.There’s not much difference in terms of strength or durability. The only difference is that these folding tires come in handy for people who readily travel and need foldable tires.
  • Tubular tires. These have a lesser weight and employ a low rolling resistance.
  • Tubeless tires. These tires weigh less, have better resistance, and can be driven, even if you’re riding against the wind. The tubeless quality won’t prevent you from gaining good speed.

What To Consider When Buying Bike Wheels

Buying a bike wheel shouldn’t be so complicated now that you know the different sizes available in the market.

Paired with that information, you should now consider the type of bike you have, the type of tires you’ll use, and the riding you’ll do.

Check the Dimensions

The typical dimensions for a standard adult bike should remain between 26” (66 cm) or 29” (73.7 cm) wheels. This includes wheels for hybrids and mountain bikes.

You’ll easily find mountain bikes with 27.5” (69.9 cm) wheels. But you’ll want to check whether you can easily stand on your bike when not riding. Your legs will have to reach the ground firmly for the wheel size to be satisfactory.

If you’re planning on buying a simple road bike, you’ll find the measurements written in metric. 650 MM or 700 MM would be a better option.

If you’re opting for a BMX bike, you’ll find that most bikes are fitted with 20” (50.8 cm) wheels.

Determine the Tire Width You Need

You’ll find that tire sizes are firmly based on 2 camps:

  • Thinner wheels. These wheels will give you better speed — but there’s a catch. Because these wheels are skinnier and have lesser contact with the road, they require a higher air pressure to remain strong. That results in a bumpier ride. Skinnier wheels also wear out reasonably quickly than your average wide wheel and are more vulnerable to damage.
  • Wider wheels. These wheels maintain more contact with the road. They offer a steadier ride, have more traction on the road, and maintain balance on irregular surfaces. They’re not as fast as the thin wheels, but where they lack in speed, they make up for it through dependability.

That being said, if you require a wider tire, find a tire within 26–27.5 in. (66–69.9 cm). Any wheel smaller than that will be thin.

Choose Between Smooth Tread or Knobby Tires

The most common tire treads you’ll find in bikes are the smooth tread and the knobby tires.

Smoother tires work best for riding on the pavement or racing since they intentionally maintain minimal contact with the ground. But, if you live in a space with muddy or wet trails, rough terrains, or any space where you might need more pedal power, knobby tires are the only tires you should use.

Even with smooth tires, some wheels come with a little tread pattern, making it easy to ride on different paths. But if you have knobby tires, don’t make the mistake of driving your bike on smooth roads because it’ll take more effort and slow you down.

Can I Find Replacement Wheels for Old Bikes?

While you can find replacement wheels for old bikes, it’ll be especially difficult if you don’t remember the size. You’ll find it easier to refer to the owner’s manual for further information. If you don’t have that, visit the manufacturer’s website and find your bike’s specs there.

If your bike is older and not in supply anymore, the best trick is to measure the wheel, rim-to-rim. You can also measure the wheel from the axle to the rim, then double that measurement to find an accurate size.

If that doesn’t work and you get a strange size, take your bike to the local bike shop and have them look at it. Most employees in bike stores have no problem finding the right wheel size. One look is sometimes all they need to equip you with the right wheel.

Conclusion

Bike wheels come in various sizes, use a range of tires, and fit a certain number of bikes. Finding the right one depends on your size and preferences, as well as the type of bike you have.

If you’re buying a second-hand bike, always check the wheel sizes before you pay the sum. If not, you’ll still have no problem finding the right size wheel for a bike that’ll make it enjoyable and comforting for you to bike down the road.

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