In the cycling world, not much can happen with the addition of three grams. Try to imagine the best possible upgrade to your bike that falls within this weight. Give up? Well, we thought of something for all of you 7900 users -- the Shimano Dura-Ace CS-9000 11-Speed Cassette. You read that right -- the weight difference between the 7900 10-speed and 9000 11-speed cassettes is only three grams. Needless to say, this was achieved through some clever engineering. To keep weight in check, Shimano constructed all of the sprockets over 16 teeth out of titanium. Additionally, the mid-spider carrier has been made from carbon fiber -- a rare occasion in the Shimano world. However, Shimano knows that the new Dura-Ace cassette is the heart of the 11-speed system, and its proudest feature is what Shimano calls 'Rider-tuning.' What's this? It means that CS-9000 gear combinations were created to your standards. And we're not speaking in hyperbole when we say that the CS-9000 has been loaded with the best sprocket ranges that we've ever seen from Shimano. In fact, the cassette is even being offered in a massive 11-28t range for the go-anywhere-rider. The Shimano Dura-Ace CS-9000 11-Speed Cassette is available in one color and in the sizes 11-23, 11-25, 11-28, 12-25, and 12-28t. Please note that the CS-9000 is only compatible with corresponding Dura-Ace 9000 components.