if you look at the difference in the number of frame parts , the Pak It is much simpler,

they and the redesigned NWT, a 20" wheel. ( there's your 20" wheel belt drive potential )

share the feature of hinging the rear section, ahead of to include the BB, so belt drive is possible..

their Silk was a rear fork , so belt skipped over the open end, ( Da Hon has some rear fork frames, too )
the rear loop stays of the others have an opening that is unbolted to let the belt pass thru..


Brompton has its rear frame section hinge Behind the BB, Bike Fridays Pocket Llama does too.
They have chain tensioners, that take up the slack when the rear fold loosens the chain.


Tikit steerer tube, which was 2 tubes sleeved over each other was replaced by a single thicker wall tube, machined down to similar dimensions..




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