i think my 1951 claud butler olympic sprint is the lightest of my bikes; fixed will always be lighter than gears on the same frame…
Quite right but, in a flash of the blindingly obvious I realised, this morning, that frame weight is partly dependant on frame size! Anyway, by this time reason has rather gone out of the window and I ended up weighing my '48 Rudge Clubman and my straight 4 speed SA '57 Rudge Pathfinder. 28lb (12.7kg) and 29lb ( 13.1kg), both with pump and empty saddlebag.
So. Modern frames are generally a little lighter, depending on how much you pay. Pretty much the same as in the 40s, 50,s and 60s. Sidevalve's old Dawes is lighter than a mid range Raleigh built Carlton/Rudge/Raleigh (Although the top end products for all three were probably comparable with Dawes, Claude Butler, and hand builds were the bees knees which few of us could afford then and even fewer now.). I am personally comfortable with what might still be called "Clubman" standard, i.e. good quality simple touring bikes that performed well and most working folk could afford. It worked then and it works now, with a small weight penalty but the advantage that most of us can fettle them , if, like me, you still rather prefer the older type of bike. (I wish my old style body still functioned as well as my old style bikes!)
Modern lightweight frames suddenly don't seem quite the advance you pay for). The biggest weight/design change over the last 60 years seems to have been the general move from steel to aluminium alloy for the bits and pieces ( I except carbon fibre, which I think is probably magic, but still leaves me uncomfortable with the idea of a bicycle that is basically knitting and glue).
Davidc's comment above also seems an important part of the debate to me. My children all ride bikes but seem incapable of any maintenance beyond pumping up the tyres and whining when bits drop off or seize up.
One further remark. In the 50s and 60's I don't recall many manufacturers offering "BSOs", which were over heavy, unreliable and simply bad value. Old fashioned engineering quality from British industry being overtaken by cheap but not necessarily good, far east made products and slick marketing convincing us we needed different bikes for different things, at least in part of the bike market. (See Davidc's posts again).
Personally I feel myself tempted to buy an Ordinary and rise above this sort of thing..