I have two late 80's raleigh reynolds 501 bikes, a kelloggs pro tour and an Eclipse.
Both are around 10 - 10.5kg in weight.
Both have alloy cranks and chainrings, (sachs hurret, custom, sakae etc) and original BB's.
They were not exactly top of the range bikes in their day, but also they werent bargain basement steel heavy raleigh/halfords stuff either.
Both bikes are as light as i really need them to be, i've already fitted more modern/lighter saddles, wheels, brakes, seatposts etc but just out of interest would i stand to gain much in the way of weight loss if i upgraded the BB, cranks and chainrings? The gears on both bikes work faultlessly so i'm not that arsed about upgrading. But if i do, i dont want to spend silly money, mid range would do me.
Otherwise what about the stem, handlebars and headset? Do the standard bits weigh silly amounts compared to modern bits? The headsets are steel, the bars and stems are alloy raleigh/custom.
I cant go single speed because i live in an exposed area with frequent high winds.
I'm not that big or heavy myself (5'10 and 11stone) so i cant lose much more weight from myself, but if i could lose another 0.5 - 1kg off each bike, my 'modifying side' would feel more satisfied lol