Dahon had a Richey break away fitted Mtb.

koga has a 20" dual suspension, but you may need to find it 2nd hand,
not a current model
http://www.koga.com/koga_uk/collecti...ion=9&pagenr=3

ive seen a blog of a canadian machinist who made a rear suspension bike

into a knock down travel bike without suspension, used the rear portion
and enhanced the separability..

LHT DLX comes from taiwan with SandS connectors, maybe 26" version too..