Shimano has released a new 3 x 10 speed Mountain Bike drivetrain called Dyna-Sys. While they cant easily be distinguished from other DEORE XT and SLX components except for a Dyna-Sys logo – technically it has been redesigned for increased efficiency and stability.
The basis of the new Dyna-Sys is that the gear ratios are closer for better shifting and the the gear combinations are ‘better’ when changing from the top or low chain ring to the middle (and back), plus the ability to stay in the middle chain ring.
The redesign is means that Dyna-Sys will increase ‘stability’ with the new lighter (10 speed) chain that is less prone to dropping plus the “Tighter cable routing and shorter rear derailleur housing make the system less prone to contamination, trail chatter or suspension movement.”
Dyna-Sys is released in addition to the current 9 speed gears and Shimano have a site setup with details and examples of the new system: www.dynasystech.com
Shimano Dyna-Sys SLX Groupset
Shimano Dyna-Sys XT Groupset