Originally Posted by
silvercreek
I inherited these hubs in a bunch of bicycle parts that one of my uncles had. There is a shallow grove or line as you call it where a freewheel would go.
Thanks for the help.
The single groove means British threads, though. No groove MIGHT be Italian, or French, or even British if the hub is old enough.
Initially, Campagnolo put no markings on the rear (Record) hubs for threading type. Then they went to the single groove for BSC (no groove could still be Italian or French during that time period), then they eventually went with the very complete call-outs around the freewheel mounting surface for the three types. But I'm not sure whether Tipo hubs did exactly the same thing (I guess I would guess that they did, however).