This 12 speed cassette is great for climbing the steep grades in the mountains where I ride.
The new 12speed Shimano cassette is part of the updated groupset. Like all of the Dura Ace components it's well crafted and allows for smooth and efficient shifting.
As a person who climbs a LOT the 11-34 is perfect for both rolling hills and long sustained climbs, the weight is managed by balancing titanium cogs with aluminum, adding strength where needed and lightness in concert.
I will use it with my new DI2 set up when I get all the parts.
