Hi all! Firstly, I hope this is a valid question for this sub. I’m an absolute bike novice, being honest. I’m looking at getting a child seat for a bike with the pictured rims and it’s required to have 26” to 28” wheels for the purposes of the seat. From a simple measure of rim diameter and reading the text here, the rims are showing consistently as 24.5”/622mm. This is a numpty question but is it as simple as that?
When I watch a YouTube video on measuring wheel size, they confirm a 622mm as being a 28 inch wheel but I can’t follow the logic. Appreciate any insight!
by Distinct_Meringue745
3 Comments
It says 622×21, so it’s a 28″ compatible rims with 21mm internal width. If you want to make sure – check the tyre size, probably it’s 28″ x 1.5″
Not too sure where you’re getting the 24.5″ but a 622 wheel is a 28″ wheel. (A little side note of confusion, 29″ and 700c wheels also have the same diameter of 622)
ETRTO 622 = ISO 622 = 700c These are sizes used when referring to rims intended for road/hybrid use and the tend to be narrower in width e.g. 21mm
ETRTO 622 road/hybrid is *equivalent to* 29″ MTB wheel
ETRTO 622mm is the Bead Seat Diameter (BSD) – essentially the width where the tyre ‘seats’, not the outer diameter.
29″ is the outer diameter including the tyre on MTBs.
Yes, it **IS** confusing!
See: [Bicycle Wheel Sizes Explained](https://www.montaguebikes.com/folding-bikes-blog/2019/06/bicycle-wheel-sizes-explained/)
**TL;DR** it’s big enough for the child seat.