This happens too much to me. It left me in a rainstorm 5 miles from home last night. Usually it occurs when I'm really cranking, for instance from a stop-light in too big of a gear, or up a short steep incline, I'll really be mashing (and probably turning), and the rear wheel will skew itself in the drop-out. That of course changes the V brake geometry and greatly increases drag. But since I'm evidently a simpleton, I say, "gosh this hill's steep" and peddle even harder. That's usually when the chain snaps. I hate fixing broken chains, but especially hate it in cold rain.

I've tried loosening the quick release skewer, I've tried tightening it too, that hasn't helped. The bike's a Specialized Rockhopper (hardtail), and the drop-outs don't appear damaged or anything. If horizontal drop-outs are 90 degrees, vertical 180, these are probably 135 degrees. If any of that matters.

Thanks for any advice!