In 2009 SRAM announced their breakout XX groupset in 2×10 speed.  One of the major features of the group is a 10 speed cassette milled from a block of billet steel which is incredibly light as well as having great mud shedding capabilities.  Yesterday SRAM announced that this cassette is now available in a 9 speed XO version.

Seven of the cogs on the 9 speed version are CNC-machined together out of a single block of billet steel, creating an incredibly lightweight, precise, and strong cassette.  The end result is incredibly light at a mere 175 grams.  Compare that to the current XTR cassette at 224 grams.

The negative is the price, currently quoted at 300 US Dollars.  The current top end 9 speed cassette,the PG-990, retails for about €85, something of a jump then.  The 10 speed XX specific cassette is a whopping €334 making it only for those with deep pockets.  Despite this  SRAM have been inundated with requests from bike companies for the XX group and sales would seem to back this up leading to problems with supply towards the end of 2009.  The 10 speed cassette takes 9 hours to produce start to finish and we saw the various stages of production in a presentation last year.  It does explain the high price and it will be interesting to see if SRAM can do anything to speed up this process and bring down the price.

The image below shows the spider and rings that make up the main body of the cassette (this is the 10 speed version).  As you can see it is all one piece.  This is a finished product from a 6 inch cylindrical block of steel that has been through a number of  CNC machines to reach this stage

The idea came from a total rethink of how an MTB groupset should or could be designed.  The improvements in the XX groupset are mainly common sense and come from a rethink rather than space age science.  The challenge is to make something like this cassette cheaper to manufacture, something that seems to be happening given that the 9 speed cassette could be as much as €100 cheaper than the 10 speed version.

SRAM tell us that the cassette should last twice as long as a normal cassette due to the steel construction on all but the inner and outer rings (which are aluminium).  Time will tell, we are expecting an XX equipped test bike shortly which should give us something of an idea.

Features
Weight 175 grams
Technologies X-Glide, X-Dome design
Speeds 9 speed
Materials CNC’d 4140 chromoly steel
Large cog material AL-7075-T6
Lock-ring material AL-7075-T6
Gear 11-32 (11-12-14-16-18-21-24-28-32)
MSRP $300
Available Mid March