Update:
I'm now pretty sure it is a Boisis, and not a Barra
Nicola
Barra ~1938?
frpm the M-Gineering study collection
(c) 2011
Before
WO2
framebuilders in France built sophisticated bikes which even now
look modern. The aluminium frame
shown below is a nice example. Handbuilt , welded by hand
with
oxy-acetylene, equpiped with novel cantilever brakes and with
great
details Builder is Nicola Barra, who first worked on his own,
during
the war for Garin, and after the war again for himself. This is
an
early one, later post war bikes have the framenumber on the
headtube.
Overview of the mixte frame. 1400 grams as shown with
headsetcups, rearbrake, seatcollar and BB cup
seatcollar
To provide clearance for the narrow cranks l (Stronglight 49D
with Rosa
chainwheels (48-32) the lefthand chainstay is indented as
well
The originale cantilever. Pivots around the bolt, which isn't
the best
of idea's: It increases the chance of the bolt loosening
The brakepivot on the fork, with the hole for the returnspring
The brake in pieces The pivotbolt clamps the washer with the
lip, which
catches the brakearm before this hits the frame
Try welding this with a torch
Rear dropouts with the original cotton insulated wire. The
frontfork is
stamped 111 too
Steerer with extension for the external clamping stem
Front dropout. And yes that is a crack, but you should see the
other
leg!
(frame isn't my size anyways ;) )
Twin plate crown shows how the fork was constructed. The
topplate is
welded to the forklegs, the lower plate is attached to the
steerer.
Next the subassemblies are slid together, and welded where
accessible.
Many ventholes, not only convenient for the wire, but also
necessary to
wash out all the corrosive flux
The dimensions of the 52,5cm frame. It is the most flexible
frame I've
had the pleasure of of putting on the alignment table: 40
Nm/degree,
while a Columbus SL
etc would be closer to 80 ;)
Literature
Raymond Henry, : Nicola Barra, French Frame builder, Proceedings
12th
International Cycling History Conference
Bicycle Quarterly Summer 2008 issue