SRAM GX DH CASSETTE is 100% made of steel and its main argument is its price : 36 euros / 30 UsDollars. Also known under its product code SRAM PG-720, it is mainly dedicated to Downhill but can also be used to any aggressive kind of ride. This cassette is part of the new and really affordable "light" groupset SRAM GX DH launched at the beginning of June 2016.
The SRAM PG720 GX DH cassette is designed to be used with an 11 speeds chain and can only be mount on a standard splined freehub body (usual Shimano and Sram). It does not required any SRAM’s XD driver as the cassette is equipped with a first gear with 11 teeth (only a start à 10T and lower request a specific driver). The cassette is composed of the following gears: 11, 13, 15, 17, 19, 22, and 25t.
7 effective gears are a logical choice for DH because it allow to have a quicker gears change with only 7 gears to manage from 11 to 25t or inverse and less teeth differences between each sprockets to prevent from "breaking" your pace. Of course a 7 speed cassette do not fill all the space available on the freehub, it is not large enough. This is why the remaining "free" space is filled with a large aluminium spacer that have the role to prevent the chain to run into the spokes. It also have an interesting second "rôle" to play in case you have bent your dérailleur hanger : it keeps it far enough from the spokes and allow to finish you race without ruining your rear wheel.
Available since June 2016, meaning right now, the cassette weight 224g and is compatible with the SRAM X01 DH 7-Speed groupset. This is really interesting because it means that if you really have a crush on the SRAM X01 DH but you do not wish to change your rear wheel because you have a splined freehub, it is now possible by mixing the groupeset Sram X01 DH with the SRAM PG720 GX DH cassette.
Find a complete review of the SRAM GX DH entire groupset right here :
English / Bikerumor : http://www.bikerumor.com/2016/06/02/sram-doubles-down-on-gravity-1x-with-affordable-gx-dh-group
French / Velochannel : http://www.velochannel.com/sram-2017-transmission-gx-dh-19389
SRAM GX DH Cassette PG720 : Weight 224g - 7 speed 11/25T - only compatible with an 11 speed chain like the Sram PC1130.
Price : 36 euros - 30 UsDollars
Website : https://www.sram.com/fr/sram/mountain/family/gx