There are lots of rollers around here, and what I've encountered is the leap frog effect. I'll on-your-left a guy (or two or three) on a flat or an upgrade. Well, they can't stand being chicked, so on the next little downgrade they shift up to some tall gear, mash it and fly past me. Once the grade goes back up they're all out of steam and I hear them madly changing gears as I glide by at the same steady cadence that I was turning down the hill. Grade goes up, I go by and so on, repeat. I think it's an extra fly in their chamois butter that I'm passing them on the UPhill .