A simple Guide on Bicycle Wheels
Most of our customers are not experts on cycling and they don’t actually need or want to become experts on cycling. But they do need to gain some basic understandings of the bike when choosing a bike to buy, such as the size of the wheels, frames, pressure when pumping the tyres, seat height, etc.
We will continue provding some simple guides to the essential things a utility cyclist needs to know and this article is about WHEEL SIZE.
There used to be three old measurement systems for wheels: Imperial, Metric & American. And this has caused many confusions when choosing bikes and wheels, as well as choosing tyres and inner tubes or trying to figure out what pressure to pump the tyres up to, especially when there are so many different notations such as 26“, 622mm, 700c, 29er, 28x1 ½, etc.
However and fortunately, there is just one consistent system now: ISO 5775.
The ISO measurements are in this format: ISO section-diameter (e.g. 28-622). For most bikes, 622mm ist he common diameter. For 622mm, the common tyre section widths vary from 18 to 47mm with 25mm to 37mm most useful for utility cyclists. If you read on your tyre sidewall this confusing sequence: 28-622, 700x28C, 28 x 1 5/8 x 1 1/8, that means the rim diameter is 622mm and tyre outer diameter is around 700mm (the actual outer diameter will depend on the tyre’s height). The tyre width is 28mm. The tyre height is 1 5/8 inches. http://www.ctc.org.uk
Note that the rim diameter is the accurate measurement. Tyre height varies (e.g. road tyres vs MTB tyres) so the outer tyre diameter varies with it. E.g. For a 622mm rim, you can have outer tyre diameters of 670mm (road tyre), 700mm (cyclocross tyre), 736 (MTB tyre).
You can run a range of tyres widths on the same rim width according to recommended ratios. (The ideal relationship between tyre and rim section is about 1.8 to 1, but any tyre from 1.4 to 2.2 times should fit – always provided that the bead diameters correspond. ) http://www.ctc.org.uk
You should stick to a standard diameter when buying a bike. Most adult bikes now have 700C wheels with 622mm rim diameters. However, basically there are 3 common wheel sizes which you can consider as Large (622mm rim diameter), Medium (584mm) and Small (559mm). https://www.rivbike.com