Chuck - as far as fork tang dating goes - I still have the fork from my wrecked Colnago that has two holes in the fork crown tangs and was purchased by me in March/April '73. I was working in a bike shop then and it had just come in from the importer (Mel Pinto?) so I don't think it had been sitting around for any length of time - I have no way of being certain when it was built. Hope this helps. BTW, it did have another feature of '73 bikes - water bottle brazeons.
Roman Stankus
Atlanta, Ga USA
> -----Original Message-----
> From: classicrendezvous-bounces@bikelist.org
> [mailto:classicrendezvous-bounces@bikelist.org] On Behalf Of
> Chuck Schmidt
> Sent: Monday, September 10, 2007 12:47 AM
> To: Classic Rendezvous
> Subject: [CR]Colnago dating...
>
> Colnago Frame Dating, Version I
>
> 1969 and earlier?
> 1969 -- Playing card decal graphics
> 1969 -- Fork crown (sand cast) with clubs in top and two
> holes in each side
> 1969 -- Fork tangs wide, no cutouts
> 1969 -- Club cutouts in all three lugs
> 1969 -- Bottom bracket shell with drilled holes in circular pattern
> ----
> 1970 -- Club cutouts in all three lugs but club in lower head
> lug is now larger 1970 -- Fork crown (investment cast
> semi-sloping) with clubs in top and two holes in each side
> 1970 -- Bottom bracket shell with club cutout
> ----
> 1971 -- Fork tangs narrow, no cutouts
> ----
> 1972 -- Club/COLNAGO decal on head tube and seat tube with
> Worlds bands and COLNAGO on down tube
> 1972 -- Fork crown with clubs on top and two holes in each side
> 1972 -- Fork tangs with two holes
> ----
> 1973 -- Wreath seat tube decal with two Worlds bands
> 1973 -- Fork crown with clubs on top and no holes in each side
> 1973 -- Fork tangs with club cutouts
> 1973 -- Club cutouts in all three lugs
> 1973 -- Water bottle braze-ons on downtube
> ----
> 1974 -- Vertical COLNAGO seat tube decal with diagonal worlds stripes
> 1974 -- Club cutout in lower head lug only
> 1974 -- Shifter braze-ons on down tube
> 1974 -- Short Campagnolo dropouts (?)
> ----
> 1976 -- Fork crown with COLNAGO added to clubs on top
> ----
> 1977 -- Top tube cable guide braze-ons
> ----
> 1979 -- Fork crown for recessed brake bolt, shallow triangles
> cut into back
> 1979 -- Brake bridge for recessed brake bolt
> ----
> 1980 -- Short COLNAGO drop-outs
> 1980 -- Fluted seat stay caps engraved COLNAGO and straight
> seat stays, no longer biconical 1980 -- Brake bridge with
> cast square boss for recessed brake bolt
> ----
> 1981 -- Chain stay bridge is small spool shape, no longer tube
> ----
> 1982 -- Chain stays stamped COLNAGO on sides
> 1982 -- Cable routing on underside of bottom bracket
> ----
> 1983 -- Aerodynamic fork crown
>
> NOTE:
> Year dates are approximate; changes might have occurred the
> end of one year or the beginning of the next for example.
> Paint schemes, decals, panels and chrome varied according to
> how importers spec'd their frames, so this all varied
> considerable. Dates and details based on the Classic
> Rendezvous archives, the Wool Jersey Gallery, and Colnago and
> Bikcology catalogs.
>
> ALL CORRECTIONS WELCOMED AND ENCOURAGED!
>
>
> Chuck Schmidt
> South Pasadena, CA USA
> http://www.velo-retro.com (reprints, t-shirts & timelines)