Amazon offers postal scales now for about $30, and these scales have 5g accuracy, more or less (if you zero them correctly, and weight stuff 2-3 times.)
I bought one just for fun and took advantage of it to weigh all the bare framesets in my garage :
http://www.ece.ubc.ca/
There were Reynolds 531 bikes ( Raleigh Team, International, Competition ), Tange #1 bikes ( SEKAI 4000, i believe), and reynolds 501 bikes (TREK 500, 1985). The sizes ranged from 22.5" (c-t) to 24.5" (c-t).
The total frame weights ranged from 2854 ( a 1950 Carlton Flyer 23" with pencil stays, and a chater-lea shell ), to 3170 ( a 1985 TREK 500, with an investment-case head-tube, and a frigging-light fork!)
The lightest fork was 706 grams ; the heaviest, 868 grams.
I was quite surprised to find out that all these different frames, in varying sizes and over a 35-year period, weighed about 3020 grams or 6.65 lbs, +/- 100 grams, more or less.
- Don Gillies
San Diego, CA, USA