The Shimano HG-400 9 Speed Cassette is ideal for replacement and repairs on 9-speed mountain drivetrains, though it can also be used on compatible 9-speed road systems as well. Technically it was developed for the needs of Alivio M4000 mountain use. The design features the 5 large cogs pinned to a steel spider, 4 loose cogs, 2 resin spacers and two small cogs that integrate, with the large having built in spacing. The smallest cog then is placed in, and a standard steel HG cassette lockring is used to fasten the cassette to the freehub body. All cogs are nickel plated for increased surface durability.

Shimano offers several combinations of the HG-400, but availability can vary. It was designed for the 8/9 speed HG freehub body length but spacers can be used as needed on longer models. Keep in mind that some of the original complete Shimano 6600 and 7800 wheels had rear hubs that were 10-speed only, and not compatible with 9-speed cassettes. You will find the cogs feature tooth and ramp designs that have long been a Shimano engineering technology for faster, more efficient shifts and better chain engagement.