Originally Posted by
juvela
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the combination of this BOCAMA lug pattern with this seat stay treatment, Georg Fischer Swiss thread sandcast shell with the prominent lip on the drive side certainly shouts "Allegro!"
the 28.6mm tubing diameter is definitely puzzling; you could verify by taking measurements in different spots
one inquiry you could make would be to examine interior of head tube to see if there is any evidence of headplate fastener holes being filled in
while in there you could check for signs of original colour
shall look forward to reading what our numerous Allegro experts have to communicate
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As [MENTION=333224]juvela[/MENTION] put it, the Bocama 14 type II lugs, seat stay wraparound treatment, sand-cast Fischer BB shell threaded for Swiss DO shout "Allegro!" The wraparound seat stay top is IDENTICAL to the one I had on my c.1974 model 76, which I found notable. I don't recall ever seeing a wraparound top that looked exactly like that, and it sure looks like an Allegro to me.
The things that argue against it being an Allegro are the seat post diameter (26
.8 mm vs. the 26.6 mm, which is both what Allegros I have encountered took as well as being about the largest diameter post one can fit into a metric sized, 28.0 mm seat tube. Also, the lack of the serial number ingot on the left side of the seat tube.
The lack of head tube rivets is not a determining factor here. Allegro used both riveted metal headbadges and head tube decals.
The database info I gathered shows sn 175513 with Nervex Pro lugs (c.1960) with a decal, then 195448, 208420, 210909, and 224502 with head tube decal and Bocama 14/II lugs.
Have ALL the tubing exterior measurements been checked to be certain they're Imperial all the way around? Is it possible that this bike was originally an Allegro; for some reason it became necessary to replace the seat tube, and the repair was done by reaming things out a bit and squeezing an IMPERIAL seat tube into a metric 531 frame - while adding bottle bosses and top tube cable tunnels and shaving off the fender eyelets?
I know the serial number is stamped -
1
94741
but if we read it as 194741 that would point towards an early '60s frame with Bocama 14/II lugs that someone restamped on the BB shell - those numbers look like they were stamped later - that someone repaired and modified and repainted.
Or am I just really, really reaching?