looking into a older dahon eco (not sure if its a c3 or c7 - it has 7 speeds) on cl. what im wondering if the bike lends itself to upgrades? bars, saddle, gearing, crankset, derailleurs, basically the works.

on another note, is the tern d8 upgradable? theres not much folders available here. this is my first one so not looking to jump in on a $1500 brompton or bike friday just yet