Shimano has unveiled their Di2 set for triathlon / time trial bikes.  Called the ST-7971 Dual Control levers, they give you the option of shifting from either the brake levers or the extensions.  For those of you who don’t ride TT or Tri bikes, usually the shifters are only positioned on the extensions at the end of the aero bars, making shifts awkward when climbing.  With the new Di2, you can keep your hands where they need to be for the task at hand.
So, they’re convenient…and did I mention light?  The brake levers are carbon and weigh in at a feathery 127g/pair.  The SW-7971 extensions are only 103g/pair, a whopping 75g lighter than their (7800) mechanical counterparts.  They run the wires through the aero bars to keep the wind resistance down, too.
They’ll work only with the only new electric Di2 derailleurs from Shimano, which you can see in action in our video from Interbike.  They should be on the market about three months after the regular Di2 parts hit in January.
