In this modern era the choice for wheels/tires has pretty much been limited to two sizes: 26 inch and 700C. Pretty much 99% of bikes meant for adults you’ll see in stores will be one or the other. 26 inch (bead seat diameter of 559mm) is the standard for mountain bikes and cruisers. 700C (b.s.d 622mm) is the standard for road bikes and hybrid/comfort bikes. That’s pretty much it.
But that of course hasn’t always been the case. There are plenty of other sizes that have been used for adult bikes over the years. A run-down of some of the most common oddball sizes, from largest to smallest:
- 28 inch (635mm): Used for olden rod-brake roadsters in the UK and Europe
- 27 inch (630mm): Commonly found on road bikes (aka “10-speed”) in the 70’s and 80’s
- 26″ x 1 3/8″ (590mm): Found on most British three-speeds and some American adult utility bikes, three-speeds, and low-end ten-speeds up until the 1980’s. Both of my British bikes use this size wheel, and if you’ve read my blog long enough, you know that I like this particular size. Also known as EA3 or 650A.
- 650B (584mm): This size is very much French, as French sizing is all number-number-number-letter. Commonly found on older French touring and utility bikes. Once considered dead like Latin, this size is making a big comeback and has its share of fans. (If you want to look cool at any randonneuring event, mention how you’re getting a custom bike with “low trail” and 650B wheels. If the conditions are right, you just might get laid.)
I spotted this bike last week:
From a distance you can tell it’s small. But how small, you ask? Well, I didn’t measure the frame size but I saw the size of the wheel: 24″ x 1 3/8″. Now a 24 inch wheel isn’t super-rare by itself. It was a common “juvenile” wheel size for kids too big for 20 inch wheels and too small for 26/27. My first ten-speed was a 24″ Huffy that I got around 1986. But this size pretty much faded away for the most part in the modern era. (Sheldon Brown blames the death of the 24 inch size on “wheelie” bikes.) But as there is more than one 20″ and more than one 26″ size, there are multiple size that fall under the 24″ banner. These are the ones I could find via Sheldon Brown:
- 507mm (24″ x 1.5″-2.125″): Juvenile mountain bike and cruiser. I’m guessing this is the most common one.
- 520mm (24″ x 1″): High performance 24. Used by Terry.
- 540mm (26″ x 1 3/8″) Juvenile road bike size used in the UK and Europe. Also known as 600A.
- 547mm (24′ x 1 1/4″ or 26″ x 1 3/8″ Schwinn.) Looks like it was mostly a Schwinn size, because Schwinn was notorious for doing wheel sizes just slightly different. In Schwinn sizing it’s also known as a S-5.