I've been thinking about bike sizing and wheel sizes lately. I've got too many friends under 5'3" riding 29ers and crashing because they're either clipping their foot on the front tire when they turn (due to the short top tube), bumbling around corners, or they're having a tough time just handling it, whether it be switchbacks, getting on and off, or even loading it into the car.
So here's my crazy "logic."
Someone 5 feet tall (60") would fit best on a 26" wheel max in my opinion. This allows for ebery meausrement to ve smaller: chainstay, top tube, standoverstandover, and the front tire is smaller, so they won't clip it while turning. They'd be lower to the ground, have more standover clearance, and be able to have more confidence and be able to handle the bike better.
Now, I realize 26" isn't popular anymore (except at rampage and all slopestyle events), but I think it still has a place, especially for small riders (kids, women, small dudes, etc.) Dividing their tire size by height, we see that their wheels are 43% of their height for a 5'0" rider on a 26.
So let's take someone 6'3" (75"). I'm oversimplifying , but 43% of their height would put them on a 32.5" wheel. That's a HUGE difference. Imagine riding around with a 32.5" wheel. It would affect a lot of things. It would roll faster, but switchbacks would be insane. Wheelbase would need to be insane or you'd hit your feet on the front wheel. Getting on and off would be tricky. Jumping, wheelies, manuals would be very different. Your chainstays would be a mile long. And that's just got a hardtail. Imagine designing a 32.5" wheel to still have clearance after 4-6" of uptravel.
So here's a little more analysis. With the 43% ratio
5'0 on 26" wheels = 43% of their height
5'6 = 28.6" wheels
6' = 31.2" wheels
6'5= 33.3" wheels
5'0 on 650b wheels = 46% of their height
5'6 = 30.3" wheels
6' = 33.1" wheels
6'5= 35 4" wheels
5'0 on 29" wheels = 48% of their height
5'6 = 31.9" wheels
6' = 34.6" wheels
6'5= 36" wheels
Looking at these numbers, even a 26" wheel seems a little big for someone 5' tall.
I'm oversimplifying, and there's more that goes into this than height, but it's obvious that some wheel sizes suit different heights better. Someone 5'0 rissong a 29er is like someone 6'5 riding a 36er.