Understanding Bike Tire Sizes: A Guide to 40-622, 700x38c, and 28x1 5/8 x 1 1/2
When it comes to buying a new bike tire, understanding the size can be overwhelming. With various measurements and notations, it's easy to get confused. In this article, we'll break down three common bike tire sizes: 40-622, 700x38c, and 28x1 5/8 x 1 1/2.
40-622: The ISO Measurement
The 40-622 notation is based on the International Organization for Standardization (ISO) measurement system. This system uses two numbers to describe the tire size:
- The first number, 40, represents the tire's width in millimeters.
- The second number, 622, represents the tire's bead seat diameter (BSD) in millimeters. The BSD is the diameter of the rim where the tire bead sits.
In this case, the 40-622 tire has a width of 40mm and a BSD of 622mm.
700x38c: The Traditional Notation
The 700x38c notation is based on the traditional French system, which uses two numbers and a letter to describe the tire size:
- The first number, 700, represents the tire's diameter in millimeters. However, this is not the actual diameter, but rather a nominal value.
- The second number, 38, represents the tire's width in millimeters.
- The letter "c" represents the tire's width profile. In this case, "c" indicates a narrower, more traditional road bike tire profile.
28x1 5/8 x 1 1/2: The Fractional Notation
The 28x1 5/8 x 1 1/2 notation is based on the fractional system, which uses inches and fractions to describe the tire size:
- The first number, 28, represents the tire's diameter in inches.
- The second number, 1 5/8, represents the tire's width in inches.
- The third number, 1 1/2, represents the tire's BSD in inches.
In this case, the 28x1 5/8 x 1 1/2 tire has a diameter of 28 inches, a width of 1 5/8 inches, and a BSD of 1 1/2 inches.
Conversion and Compatibility
When buying a new tire, it's essential to ensure that it's compatible with your bike's rim. You can use online tire size conversion charts or consult with a bike mechanic to ensure a proper fit.
In summary, understanding bike tire sizes requires knowledge of the different measurement systems and notations. By recognizing the ISO, traditional, and fractional notations, you'll be better equipped to choose the right tire for your bike.
