I stared at that for 5 minutes before I figured it out and I Fricken Like It !!
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Most folding bikes (at least every other one I've seen) have a pivot like this,..
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The pivot and lock are in the same 2"X2" area.
There's way too much stress and the pivot either breaks, jams shut or open, or loosens up and your frame wobbles in the middle.
Art's bike pivots around a much longer, tighter axis, and locks to the frame about 4" away from the pivot making it WAY more stable, durable, and reliable.
To convert Art's folding mechanism to a similar design as the others I've seen, you would remove the entire metal triangle beside the water bottle then drill two holes through the seat post where it pivots and install two pins to lock the pivot.