That's the great thing about "trials" bikes JP

They'll "climb a house side" as we used to say

Back sprocket "like a dustbin lid"

(for those who remember what one of those is

)
I once saw a BSA Bantam,
[and I'm NOT exaggerating]
With a back sprocket "almost" as big as the back wheel

You could only see about 3 inches of spokes past it

It was a "circus" bike though

But on a more serious note, that story of yours
Just reinforces my point about BIGGER sprockets gearing the bike down as a "Cub" was always good for 60-65 mph on "standard" gearing