Hi, A three-speed gearbox is a lot heavier than a two-speed gear assembly, the duplex Flyer frame is a lot heavier than a Super Squirrel frame, and Webb, Brampton, and Dowty forks are much heavier than Super type forks. Then we have the hubs and brakes, more substantial mudguards, ditto footrests, bigger tanks, and so on. It all adds up to a big difference. I can’t quote you any actual figures for the components, and perhaps someone with a bike asunder, and a handy set of bathroom scales, will oblige…….
Brian