I’ve just bought a secondhand bike (with an ~80’s Dawes steel frame) and on checking it over I noticed there’s a gap on one side of the forks, where it meets the dropout. The top side and bottom of the fork appear to be joined it’s just this portion on the rear/bottom of the fork.
The bike is an 80's steel construction, so it's highly likely these dropouts are brazed into the slots in the tip of the fork tines.
This ride has survived 40+ years, so clearly it is "strong enough"
The cause will be slightly insufficient bronze filler used while brazing, or possibly shrinkage pulling the filler metal inward on cooling.
To relax your concerns, try removing the wheel and cleaning both dropouts with warm soapy water. Then dry with warm air. Once completely dry, use a tiny sliver of paper to measure the "depth" of the opening. I expect it to be millimetres at most.
A visual-only fix would be to use plastic filler or bog or epoxy to close the hole, then sand and paint over it. If you can't match the paint, then a small plain matt-black area over the dropouts would look fine too.
IANAFB (frame builder) but…
The gap doesn’t look to be crash damage, the paint is all intact and there are no stress riser cracks. You can see the top of the dropout piece through the breather hole.
The fork is overbuilt steel and the loads on the drop out area are vertical and compression towards the inside. If it was my bike I’d be OK with it.
At a guess it’s a manufacturing glitch and you’ll be fine but when you get a chance show it to a bike shop or a person who welds for another opinion. Asking random enthusiasts on the internet about your personal safety isn’t a great idea.
I'm going to be slightly contradictive to the other answers on this one. To me looks like the metal around the gap is bulging and miss-shaped as if it has had some twisting or lateral stress on the dropout which has broken the braze at some point.
Being steel, probably is still fine to ride but would think it's an idea to get into an engineer to get the weld fixed properly sooner than later to minimise risk.
Or just call it a feature for draining.
