Courtesy of wikipedia.

Among the many choices you need to make when selecting the right bike for you, one of the more important decisions is size. This doesn’t mean just frame size, but also the size of the wheels.

You may not be familiar with the different sizes of wheels available on road bikes, mountain bikes, folding bikes, etc. – heck you might not even care. Read on to find out what sizes are available and why you should care, or at least have a cursory knowledge of bike wheel and tire sizes.

Looking at the number of different wheel sizes available from 16” in diameter all the way up to 29” (or 700C as they are referred to on road bikes) the number of choices can be overwhelming at first. Below, we break it all down for you to help make understanding wheel sizes as easy as, well, riding a bike.

One reason bike tire sizes can be confusing is they use both metric and non-metric units of measurement. For example, on mountain bikes, the largest wheel size generally available is referred to as 29”. On road bikes however, the  same size wheel is referred to as 700c. Go figure.

In addition to the common names for different sizes, the exact diameter of a wheel (the metal rim) in millimeters is known as its ISO diameter. These standard sizes are defined by the International Organization for Standardization (also known as ISO).

16”, 20” and 24”

A 16" wheel.

If you ride a unicycle, BMX bike or have been to the circus than you have seen what are generally considered to be the smallest wheels available on a bicycle. A number of other folding bike companies use these small wheel sizes in order to have a more compact size when folded.

While the smaller wheels produce a smaller folded package, many people find them to be less stable than their larger counterparts and they tend to provide a slightly bumpier ride on rough road surfaces. A larger gear ratio is also required when running a smaller wheel and this can lead to some difficulties when you take those little wheels up a steep hill.

These size tires generally come with treads designed for on-road or light off-road use. Some knobby tires can be found in smaller sizes for BMX and for use with children’s mountain bikes that use these smaller wheels.

26”

This is the most common size for mountain bike tires. The diameter of the rim is 22” (ISO 559) but the diameter to the outside of the tire is 26.2”. For this reason, these tires (and the wheels) are usually referred to as 26″. Tires for 26″ wheels are available in a variety of widths and treads to accommodate different width rims and riding different terrain. All of Montague’s full size folding mountain bikes use 26″ wheels.

29”

In the 1980’s bigger mountain bike wheels began to gain popularity. Often referred to as a 29er, this wheel size has the same diameter as the “700C” wheel common on many road bikes. The diameter of this rim is about 24.5” (ISO 622) and the diameter to the outside of the tire is about 28.5” (I guess 28 and a halfer doesn’t have the same ring to it!) These 29ers have seen a bit of a resurgence lately and when it comes to mountain biking, those that prefer 29” generally feel the larger tires:

  • roll over obstacles more easily
  • are less likely to get stuck in sand and dirt
  • have better traction due to their larger contact area.

This tire is far from mainstream but has gained a strong foothold in the mountain bike world.

650C

This size is generally used by smaller riders on road bikes. The diameter of this wheel is 571mm (ISO 571) and is most common on very small road frames where the geometry cannot easily accommodate a 700C.

700C

A 700c wheel.

This is the most common size of road bike wheel and has a diameter of 622mm (ISO 622). All the bikes in Montague’s pavement line use 700C wheels.

All things being equal, larger tires decrease rolling resistance. Less rolling resistance means less effort required to get you to where you want to go. Whether you are racing, touring or commuting, that’s a good thing.

What’s your preference for road, mountain bike or folding bike wheel size? (You know we prefer large wheel folders!)