FRAME DETECTIVES,i need your help !

[dorset boy]

Could it be a Diamant ?

 

[dorset boy]

Just tried a 26.8 seat post in it and it was too tight so must be 26.6,does that help with any clues to the tubing? Weighed it against my friends Ron Cooper which is the same size and mine came out a tad under a pound heavier.

 

[grubb1937]

Frame looks to be built with Bocama Pro lugs. Campag short dropouts began to appear around the late 1970s. Cable guides on top tube are from around the same time and the Campag pattern cable guide on the top of bottom bracket shell would fit the late 1970s/early 1980s. The 26.6mm seat tube diameter would point to a French frame. Are the bottom bracket threads and fork steerer tube British Standard Cycle? Mercier, Motobecane and Gitane were imported into the UK around this time. Gitane had a following because of 'the badger' Bernard Hinault's success.

 

[dorset boy]

Frame looks to be built with Bocama Pro lugs. Campag short dropouts began to appear around the late 1970s. Cable guides on top tube are from around the same time and the Campag pattern cable guide on the top of bottom bracket shell would fit the late 1970s/early 1980s. The 26.6mm seat tube diameter would point to a French frame. Are the bottom bracket threads and fork steerer tube British Standard Cycle? Mercier, Motobecane and Gitane were imported into the UK around this time. Gitane had a following because of 'the badger' Bernard Hinault's success.

Thanks for the input,the threads are British and i did think Gitane because they made a 531 with British threads.Its the serial number thats the killer,thats why i thought it could be a Diamant (Belgium) as they had there frames made by lots of smaller frame builders then badged them up,thats according to what i found on the web.Does 26.6 denote a certain tube make?
Mike.

 

[dorset boy]

Found this on the web,it was on this forum and was another mystery frame !
Also found that 531 Gitanes had 26.6 and 26.4 seat posts so the confusion continues :?

 

[torqueless]

I already suggested this could be Columbus tubing...If it's shaping up as French it could just as easily be Vitus or Super Vitus tubing, which would take a seatpost of around that diameter-(26.6)

 

[dorset boy]

I already suggested this could be Columbus tubing...If it's shaping up as French it could just as easily be Vitus or Super Vitus tubing, which would take a seatpost of around that diameter-(26.6)

Just found a Gitane on the web made from Super Vitus.

 

[lewisfoto]

I already suggested this could be Columbus tubing...If it's shaping up as French it could just as easily be Vitus or Super Vitus tubing, which would take a seatpost of around that diameter-(26.6)

Just found a Gitane on the web made from Super Vitus.

Wait I though you said it was English thread?

 

[dorset boy]

Gitane made 531 frames with English threads.

 

[iron legs]

French frame built with Reynolds 531 were metric tube sizes, hence seat post diameter of 26.6mm. If it is a French built frame but with BSC threads then this would date it to 1980 and later. Check the steerer threads and the steerer tube diameter to establish if British or French. French quill stems have an outside diameter of 22mm as opposed to British 22.2mm.