I recently built an S-Works Tarmac SL7 & the final touches were S-works Rib Cage III bottle cages. Expensive but hey, they're for my dream bike build. I initially thought that my bottles would easily pop out as they seemed a bit flimsy but no! My cycling routes, whether a commute or for pleasure, always begin with a 1 mile descent of an average -9% & a maximum -15% over several sets of rumble strips at 45mph & these hold my bottles in place everytime! With other cages I've had to keep my bottles in my pockets until I've hit the bottom, so as to not to keep losing them!) Very happy. Oh......... & they're not made of carbon, they're made of helium!!!

Bottle came out at 30mph, got wedged in my front wheel and caused a crash which broke bones.