Weird thing is that the hook is a newish development. My wife had a Dutch bike with hookless steel rims. I was baffled by them but they worked and that was with inner tubes. My laymans understanding is that when there is air pressure in the tyre it is expanding in all directions so pushing the tyre bead up against the rim.
Weird thing is that the hook is a newish development. My wife had a Dutch bike with hookless steel rims. I was baffled by them but they worked and that was with inner tubes. My laymans understanding is that when there is air pressure in the tyre it is expanding in all directions so pushing the tyre bead up against the rim.