I haven't actually measured it, but it is one of the new external BB Sora 9s triple cranks.

I estimate it to be a little over 1mm. I just know I was able to set up the FD without any chainrub at all in any gear with the square taper Tiagra cranks, but there is some chain rub cross chaining the last 2 cogs. The frame is a little flexible around the BB, so it is even worse when riding.