Originally Posted by
thetiniestbike
... Should I consider the Straggler 650b ...
No. 650b is a slightly smaller than normal rim that takes a larger than normal tire, and does not effectively reduce the wheel size, or certainly not much. You might consider 650c, which is an even smaller rim that takes narrow tires, for an effectively smaller wheel, but 650c bikes tend to be racy, so not really a good option.
The problem with big wheels (650a, 650b, 700c, 27", etc), for a small person, is that you cannot get the handlebar low enough for an efficient riding position.
26" --the mountain bike size, not the English 3-speed size (26 x 1 3/8", also known as 650a; there are actually five different rim sizes that are all called "twenty six inch") is a good wheel size for a relatively small person, but I don't know what frame I'd recommend with that. Possibly an older mountain bike with no suspension, but they tend to be built long, with a high bottom bracket, so they tend to fit like a larger frame.
I have seen older bikes made for 24" wheels that actually fit 26" wheels quite nicely; but putting one of those together might be quite a project.