does anyone have any good threads abt full suspension hanging
It's a shame that new users are not allowed to see the search function. There are many useful threads about full suspension hanging.
Of the active users,
@JesiBel doesn't seem to get tired to link to some of the most helpful hanging threads, maybe check their posts.
@AreWeWinning and
@Gustav Hartmann also are a wealth of information on hanging. Not active anymore is
@Evelyn Lane who wrote a couple of 'famous' hanging guides here.
i want to buy a rope but im undecided between 12mm and 15mm (or less)
Rope thickness is mostly a matter of personal taste. 10-12mm are most often recommended on here, but I've also seen 20mm recommended as thickness of choice. Thicker ropes are considered more 'comfortable' while thinner ones cutting easier into the neck to compress the carotid arteries. (But in the end it shouldn't really matter with full-suspension hanging, because the full body weight is more than enough to compress everything in the neck, in my understanding.)
Sturdy ropes typically start at around 10mm. My personal favorite is a 9mm, though, that's still very sturdy (I go with standard 'EN1891 type A' * ropes for industrial climbing and rescue missions, but that's probably overkill.) It just gave me the easiest passing out experience when trying it out.
(* EN1891 Type A refers to a standard for low-stretch kernmantle static ropes used in applications like rope access, rescue, caving, and work positioning, where minimal elongation is critical. To be classified as Type A, a rope must meet specific technical parameters: a diameter between 8.5 mm and 16 mm, a maximum elongation of 5% under a 150 kg test load, a knotability coefficient of no more than 1.2, a maximum sheath slippage of 40 mm, and a minimum strength of 22 kN without knots. The rope must also withstand at least five falls with a fall factor of 1 when tested with a 100 kg load.)