Hilary Stone, of Bristol, England, has been working on a time line for identifying features of pre-cast lug De Rosas for some time. What follows is used by permission and is considered a work in progress by Hilary. Any comments and information left will be forwarded to help to make this a reliable guide.
"A precise and clear time line for pre-1980 De Rosas I think is virtually impossible – De Rosa at this time was quite small and the evidence from the frames suggests that De Rosa used a number of different lugs and fork crown that overlapped over quite a number of years. Almost no De Rosa frames from this time have any frame number.
Seatstay Cap Engraving
Team frames frequently have no seatstay cap engraving. Seat stay caps were also not engraved on the earliest De Rosa frames - my best guess is that the engraving started in the late 60s - 67 or 68.The first version has no heart in the O of De Rosa - my present guess is that this changed around 1973 to the second version. The second version has the heart in the O of De Rosa and this continued save for a few exceptions to the early 1990s.Circa 1976/77 (two frames are known) De Rosa used what appears to be a solid concave plug with an engraved heart on a few frames.
Team frames frequently have no heart cutouts. There seems to be two broad common types of pressed lug - ones with a short point and ones with a long point. On present evidence it looks as the two designs were in use together for several years probably something like 1972–1974. The long point definitely started before the short point lugs which seemed to come into use around 1972. And there are some medium point lugs which seem to be from the mid 70s. Most frames have heart cutouts in all lugs in the early 70s but there are a number with short and medium point lugs with only a heart in the lower head lug or in both head lugs but with no heart cut out in the seat lug. These seem to date from 1974-6. Cast lugs were introduced around 1979/80 - the cast lug frames are easily distinguished from the pressed-lug frames by the extension for the seat bolt. These cast lugs do not feature heart cutouts.
Earlier frames seem to use a wide variety of fork crowns - quite a number around 1972–4 use a Vagner 4-point sloping crown. A 4pt flat topped cast crown was adopted sometime I think over the period 1973–5. These normally had a heart engraved in them during the 1970s; team frames generally were lacking the heart. Fork tangs were plain on the 1960s frames - they gained three round holes followed later by V shape slots - the later change probably around 1976.
Bottom Bracket Shell
A shell with six slots and two hearts – one in the down tube tang and one in the seat tube tang (behind the BB) was standard for quite a long period. At some point – maybe in 1973 a large heart cutout was introduced on some frames - most had additional heart cutouts in the DT and ST tangs but some not. Some later 70s frames used BB shells with four slots rather than six. When the the cast lugs were introduced, a new cast BB shell was used with six relieved areas in the shell.
Campagnolo short dropouts definitely indicate a frame built 1975 or later but it seems that De Rosa may have been slower to adopt the Campagnolo short dropouts than some other framebuilders.
The earlier chainstay bridges are larger in diameter and with round flanges formed with the tube. By about 1970 De Rosa used a slightly smaller diameter round tube with diamond reinforcements. These continued into the early period of cast lugs. The earliest bottle cage fittings are short studs - these continued into the 1970s probably until 1973/4. Gear cable guides over the top of the BB shell were standard on De Rosas from the late 1960s. Brake cable stops/guides (generally three) and DT lever bosses were I think introduced c1975/6."
Photo: Ugo De Rosa, 2009
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