Sorry having a bit of brain fade. To get the correct chain lentgh you run the chain around both large rings (not through mech) and add two links where the ends join – is that correct.

IIRC that what Shimano suggest in their paperwork that comes with mechs etc. Ive always just run it through the mechs and when in big ring/big sprocket the rear mech should be at around a 45 degree angle.

If you have rear suspension and are following the above advice, remember to allow for chain growth when the suspension compresses, you don’t want to be ripping the rear mech off at full travel if you happen to be in the wrong gear!!!

…or, put in big ring at front, smallest sprocket at back, thread through mech as normal and set length such that jockey wheels are vertically aligned

twohats, how many extra links do you reckon putting in to account for rear suspension, I have a 4 bar linkage on my bike with c 5.5″ travel.

Size the chain as you stated, but do it with the suspension fully compressed, i.e, no air in shock or remove spring off the shock.

cheers