I recently purchased a bike with a single strap going from one bottle cage mounting boot on the seat tube to one on the top tube like the curved one in the photo.
I am new to this so please don't the P
sorry i couldnt remember the name, its a portage strap, for when bikes were rode off road and not on man made tracks/trails. So you can shoulder the bike and carry it over boulders and rivers in the mountains
Arhhhhhgh ( glazed hazey eye expression of nostalgia) I remember the days when a race involved peddling and getting off for obstacles, rather than chucking your bike off a cliff and trying to hold on.