I often find myself thinking, "Road bikes are really unique."

Once you ride one, you realize it's a completely different kind of vehicle than a city bike (a so-called "mamachari").

There are many parts available, and many are quite specialized.

And there's a lot of jargon.

Learning these things one by one is part of the fun of road biking, but because they're so cool, there are few books or websites that provide down-to-earth explanations.

Everyone starts as a beginner.

It's easier to understand when things are explained in simple terms.

From frequently asked questions, I'd like to introduce some common questions about wheels and explain them.

▲ICAN FL MAX Series Wide Rim Wheelsets (21mm/23mm inner width)

What does "inch" refer to in a bicycle? What size is it?

Bicycle sizes are often expressed in "inches."

This refers to the "tire size," not the frame size.

It's measured by the outer diameter of the tire.

The "tire" is the black rubber part, and the silver rim (which can be black if it's carbon) when the tire is removed is the "wheel."

Bicycles are sized based on the "tire" size.

The tire size is written on the side of the tire.

For example, "26 x 1 3/8."

This indicates 26 inches (outer diameter of the tire) x 1 3/8 inches (width of the rim).

When you go to buy replacement tires, make sure to check not only the size but also the width, or you might end up with tires that are much fatter or thinner than you expected.

While they might still fit, they might not match the bicycle's design or intended use.

For example, a mountain bike (MTB) with thin road bike tires would look somewhat out of place.

What's the minimum inch size for an adult bike?

This is a question customers often ask when I work at a bike shop.

Tire sizes for bicycles sold in Japan typically range from 8 inches to 29 inches.

Home centers usually stock 20-inch, 24-inch, 26-inch, and 27-inch bikes.

You'll rarely find 14-inch or 16-inch bikes unless you go to a well-stocked store.

Other sizes are almost never seen in home centers and are likely only available online.

Generally speaking, tire sizes are categorized as follows:

8-12 inches are for children's bicycles.

12-20 inches are for children's bicycles or small-wheel bicycles (minivelos).

This size is common for folding bicycles.

16-22 inches are for elementary school-aged children's bicycles.

24-29 inches are for adults.

You choose a size that fits your body.

However, this is the traditional way of choosing bicycle sizes.

For extremely small folding bicycles, adult models can be 6-10 inches.

While 12-20 inch small-wheel bicycles (minivelos) are for adults, the saddle height can be adjusted, so children can also ride them comfortably.

The most common sizes for typical "mamachari" bikes are 24 inches and 26 inches.

These might be sizes that suit the average Japanese physique.

For taller individuals (170cm or more), a 27-inch bike might be more comfortable.

What inch size is 700C?

This is a common notation seen on road bikes.

It's often displayed as 700x23c.

Bicycles primarily use three notation systems: British, French/Italian, and American.

Since they developed independently around the world, there isn't a common notation.

In this case, 700 is in millimeters.

It means the tire's diameter is 700mm (70cm).

"Inches" are a unit of length mainly used in America, where 1 inch = 25.6mm (2.56cm).

So, 26 inches is 660.4mm (approx. 66cm), and 27 inches is 685.8mm (approx. 69cm).

Therefore, "700x23c" means a tire with a diameter of 700mm (approximately 27 inches), a tire width of 23mm, and suitable for a rim shape of C.

For commonly seen sizes, it's safe to consider 650 as 26 inches and 700 as 27 inches.

However, tire sizes often lack compatibility, so you can't just pick one because the sizes are close.

Road bikes are a type of bicycle where Europe is dominant.

Therefore, road bike notations are often expressed in the French system.

If you have any questions about bicycles, please feel free to comment.

I will answer as clearly as possible.