SE bikes...

I've been thinking of getting a 24".

I'm 6'3" with a long spine.

A 26/27" mountain bike is not a comfortable riding position for me.
With the bars flat, my back is bent over too much.

A 20" is just too small, although I really like to throw them around.
(at least I used to)

Hopefully a 24" will be somewhere in between.
I've never had one before, or even spent any time on one.

Local thrift store had a Mongoose brand 24" needing tires for $40.
Mongoose was my preferred brand back in the 80's.
I know it's not the same now.

I am concerned with material.
Even back when I was 14, I couldn't have an AL frame- I'd bend it.
Nor could I have a mild steel rear triangle- I'd break it.
Had to be full Cr-Mo.
Also had to have one piece Cr-Mo crank, or I'd break or bend that.
...and a Cr-Mo stem. Breaking the bottom of a stem is NO FUN on landing.
Almost forgot- Cr-Mo handlebars as well. Broke quite a few steel/AL bars at the cross bar weld(s).