Originally Posted by
Darth Lefty
Once upon a time in the Pleistocene...
Before the 1970's, there was basically no market for adult bikes. 26" = ETRTO 559 was the cruiser bike size for teenagers and beach resorts. These cruiser bikes were used as the basis for the earliest mountain bikes, which had a boom in the 80's, and proliferated.
I think the old Raleigh and Robin Hood 3 speeds were around at least back into the 50's, often sporting 26" wheels.
And, a few made their way here to the USA.
But, alas, the old Raleigh 26" bikes and old Beach Cruiser 26" bikes had different rim sizes.
I remember my grandparents had some ancient balloon tire bikes in their barn when I was a kid. But, other than the Schwinn Stingray bikes, I don't remember anybody using the fat tire bikes until the 80's when they must have chosen to start crossing the old cruisers with road bikes or stingray bikes to make some new monstrosity.
Perhaps one of the more recent changes is the availability of wide and narrow tire sizes for any specific rim diameter. So, 26x1.5, BSD 559 may be a relatively new tire size for those wanting sportier tires for the MTB rims.
As I understand it, 650b (584 BSD) was a relatively narrow 26" tire, but MTB riders have now adopted it as a mid sized 28" wheel/rim size. I suppose re-purposing an old rim size with new wider tires makes some sense, rather than introducing a new rim size.