Your weight and riding style pretty much define why you're breaking chainstays. Still, I'm impressed you managed to break a Continental. Unless it was rust related.

I would seriously try to spin more. It does feel uncomfortable at first but once you get used to it you'll never go back. Your knees will thank you and you'll get a better cardio workout. A knee injury forced me to spin. I'm glad it did.

Or just keep buying bikes with lifetime frame warranties and cash in on something that almost no one else ever does.

Ford hasn't built an F-100 since 1983 They still make the F-150 of course.