Cyclocross Specific Components
From Cyclocross Magazine:
The continuing popularity of cyclocross has only made the need for more CX specific components more evident. For the 2012 model year, Shimano will introduce two new cranks, a new front derailleur, and two different cantilever brakes for CX use:
FC-CX50 and FC-CX70: The new CX cranks will have 46-36T gearing and Hollowtech II construction for maximum power transfer
FD-CX70: The new front derailleur is designed specifically for used\ with the new crank gear ratios as well as optimized for the harsh conditions associated with CX racing.
BR-CX50 and BR-CX70: The new cantilever brakes have better clearance compared to the BR-M550 and the performance of Super SLR. The BR-CX70 has the additional benefit of using cartridge road brake pads for easy pad replacement.
CX50 components will be available November 2011 and CX70 available August 2011