I bought this cassette to help with hills as I am riding the Copper Triangle in Colorado this year. Wound up liking it so much I bought more of them to upgrade all my bikes. Fully compatible with Ultegra 8000 series derailleurs. With this cassette I could climb Everest .
I was already running the Shimano 6800 11-32 cassette but anything I can do to help save my knees is a plus. You wouldn't think 2 extra teeth is a big deal but it is noticeable. When Shimano introduced this cassette and made it compatible with my current shifters I went for it. You will also need the 8000 series derailleur and a new chain to make it all work but when you are finished you will have a bike that can climb Everest without having to get off and walk.
Used this instead of my old 1132 cassette this year at DK200 to make the 11,000 feet of climbing a little easier and it did the trick nicely. Worked great with an Ultegra chain, compact crank and a GS rear derailleur Di2 set up. There was plenty of take up to keep the chain taught on the rough stuff cross chained and enough clearance on the 34 tooth cog with the B screw tightened up a bit.
This is a great addition to the Shimano cassette lineup. Not only does it give you some lower gearing for steep climbs it is compatible with 1011 speed mountain freehubs as well as 10 speed road wheels. This has allowed me to use my mountain bike wheels with Ultegra 11 speed drivetrain.
I bought this to give me a little more gear on the 20% climbs in my area. I had been using an 1132 on my Ultegra 6850 equipped Roubaix. It did what I wanted, with the added benefit that it fits my old 10 speed wheels. The carrier for the largest gears is concave so it will fit the slightly shorter 10 speed freehub body. You need to use a spacer for 11 speed hubs. On the down side, it's 45 grams heavier than the 1132. It works fine with the medium cage Ultegra derailleur.
Top quality Shimano cassette, this cassette is about an ounce lighter than a sram one for the same gear range and shifts a bit smoother on my one by cross bike. The extra low end is a plus on some of the steeper cross crusade courses like ninkrossie.