Brit braze on

[rfjshepherd]

I have come across a braze on for the shifter, it seems to have a brit imperial 2BA thread, will the actual shape of the braze on be compatible with the more usual campag braze on?
If not what is the solution file and tap or just file and use a 2BA screw, like used for the mudguard

 

[keithglos]

I don't know what age we are into here, but standard british frames 1950/60s tapped the fork ends 3/16, slightly larger than 2 BA, and we sometimes used 2 BA in them.
Is the gear lever boss possibly one of the later (about 1960) Cyclo?
Can you point us at some detail pictures, including fork ends.
Keith

 

[rfjshepherd]

The bike is from the early 60s. There is one braze on boss on the down tube,a campag screw is not the right thread but a screw from the fork end, attaching the mudguard does fit.
The threaded whole goes right through into the down tube.

 

[keithglos]

5mm is larger, if british thread then it could be Cyclo. Have the rear ends got a gear hanger, or signs that one has been chopped off, or any trade mark?
My guess is that it was for one of the cyclo parallelogram gears.

 

[rfjshepherd]

The bike is an Elswick Hopper Lincoln Imp. There is no gear hangar but not sure if this is original as have seen other older models with a gear hangar. If it was removed the cut is clean and been well finished. Have heard that cyclo gears were on earlier models. If that is the case and I have one of those bosses what are the options to get a normal campag braze on to fit?