If your old and frail arcsrule why not say thats the reason you use the free bar. and where talking about G-arcs here not S-arcs.
to help prevent such things check your lines every so often and replace them about once a year or less depending how much use you get out of them.
Rod, Yes I'm old...but not frail!
And i fly a G18, Preprod G12 (purple and yellow and a really sweet kite) and occasionally a 15.5 PSYCHO (that sucks). If we had the winds here that you have, your bar might work good and I'm sure it does for YOU ...but unfortunately, 15 is about as good as it gets for us and usually much less than that and to finesse the kite the way you need to keep it moving, a free bar is nice. And if you really want to milk the Guerilla, put it on 150 feet lines. In marginal wind, it makes the power stroke long and smoothe. Being old and decripit, i have no idea how the long lines work in jumping. Maybe you can try this out?
Oh yea, I don't put my 12 up in less than 18 and i'm guessing it woud go to 30 or more with no problem.