speedster93b
+1y
the size of the gusset isn't as important as placement. optimally it should extend at least halfway across the bag and go down the same amount. it's kind of a judgement call... it'll be obvious if it's too big or too small, or if you have a gnarly long gusset that's only half an inch wide... you know.
i wouldn't run a gusset any smaller than 2" on one the frame side on an upper bag mount