Clicking "My gear" you won't get the dreaded "Coming Soon" anymore :-). You'll be prompted to add some gear, so let's do it: just click "Add new"
In this case, I have used the shoes without GPS for two short runs, but I want to account for that as well, so I'll add something in the "Untracked usage" section. I think it was about 12 km. I can't exactly remember the time, or the pace, so I used a reasonable approximation for time. I slacked off a little, so you have to set time in hours, or fraction of hours, not h:m; it's untracked usage so I don't feel like we need much precision there.
Total distance is calculated by adding untracked distance to tracked activity distance. We'll see that in a moment. Same thing for total time. Cost Analysis should be pretty obvious by now; of course, it's based on total distance / time.
Let's click Ok and get back to the gear list:
When you decide to retire those shoes, just tick "retired". Retired gear won't appear in the gear list (unless you choose "show retired") and won't be shown inside activities as well (unless you open an old activity associated to that gear, in which case it will be there, read-only).
Hope you like it!