Fiamme Ergals. I used to race on these. They were light weight but I was too, then. If you were breaking them, you were probably too big or strong.
But I remember another set of rims that came on Fuji bikes (or other japanese bikes of the era) with sew ups. I don't remember the brand. They were thin aluminum, filled solid with a plasticiky/foam substance. The problem was there was no reset for the spoke nipples. They protruded on the surface where the tires needed to be glued on. After a rather short ride period, the spoke nipples would work their way thru the sewups or the glue would fail because the inflated tires would not stay glued over the bumps caused by the nipples. I remember the stock japanese sew up tires were so stiff too, they would not be bent over the nipples easily. Seems every one of those rims had to be replaced pronto.
GB handlebars. Such soft aluminum. You saw many old raleighs with drooping bars.
Not strictly lightweight bits but how about the Schwinn dual stem shifters. Certainly caused the death of a number of family jewels.
Have you covered frames yet? Teledyne Titan. early Lamberts. It wasn't just the forks that were bad. I still remember seeing one Lambert that came still in the box where the head tube snaped off the frame during shipping. The not-tapered press fit bottom bracket axles (with the groves cut in them for the snap rings) snaped off too. I sold my Lambert when the seat tube started cracking at the top. Fortunately the new owner got run over by a car and destroyed the bike before the bike could break and hurt the rider.
Cinelli M71 pedals.
Not period but Spinergy 4 spoke wheels. Ah, the sudden collapse syndrome.
Tires. I remember the tires that came on the mid 1970s raleigh grand prixs. A row of tall vertical ribs. You could feel them squish over during the slightest cornering move. It felt like you had no control over the bike.
Wing NUTS!
Rick Paulos
Davenport, Iowa.