Exactly three years ago I took my first ride aboard Shimano’s first mountain bike specific Di2 gruppo, their premier XTR line. We spent a few days riding the rugged desert mountains above Palms Springs, CA and stayed at a lush resort nestled amongst the cacti, golf courses and retirement homes. The electronic XTR group’s champagne and caviar feel suited the ritzy Palm Springs launch and all who rode the group agreed the performance was incredible and the neat-factor was equally impressive. Is it worth the price? For some it may be, but Shimano realizes that isn’t the case for most people. For that reason, Shimano has worked hard to offer a more attainable Di2 drivetrain. Available for roughly $1,300, which is more than half the price of XTR Di2, Shimano’s XT Di2 (M8050) drivetrain still shares many of the technological benefits of its XTR sibling.
Keeping in tune with the more affordable marketplace for the XT drivetrain, Shimano opted to skip the fancy media gathering for a more personal approach. I was asked to provide a frame and choose the specifications for my drivetrain of choice. After spending countless hours building an XTR Di2 bike just a couple monts earlier I was thrilled to not have to do that again! I selected and aluminum Trek Fuel EX frame as I felt it would align with the more affordable drivetrain motif.
Sadly not very many brands have jumped on the Di2 integration program as of yet, which led to some swearing on my end and a Shimano Pro cockpit being used. The Pro stem and handlebar are fully Di2 compatible and allow consumers with frames not designed for battery storage to maintain that stealthy, sano appearance. The Pro stem uses Shimano’s Headlock system rather than a traditional star nut to preload the headset bearings. This allows the steerer tube to remain uninterrupted for storage of the battery and wires. Wires destined for the display unit exit the stem and are plugged into the screen next to the stem. Another wire (or two if you run a 2x) runs inside the bar and exits from a dimpled cut-out just at the grip’s edge. It’s similar to the internally routed cable systems employed on some motorcycle bars.
Thanks to the Pro cockpit set up, my Trek Fuel looked incredibly slick with the internally stored battery and wires, despite the frame lacking Di2 integration. The downside to the Pro stem is the very tight tolerance of adjustability on the Headlock system. Steerer tube height must be within a very small range in order for the 32mm nut to work properly. Measure three times, cut once, or have some very small steerer tube spacers on hand! Aside from that my drivetrain was bone stock and ran like a charm until I bent the hanger pretty badly in a transport incident. A quick adjustment with the DAG (derailleur alignment gauge) and I was right as rain.
After spending way too many hours using foam, zip ties, masking tape and breaking a cheap drill bit I thought I’d share some input from my personal struggles for those who don’t want to run the Pro cockpit. First off, really plan out your build. Measure frame tubing lengths, measure cable lengths and familiarize yourself with the system before you start stuffing holes. In fact, I’d lay the frame on the ground and lay the battery, junction box and all wiring on the ground below the bike to replicate how the system will run throughout your frame. This will hopefully save you some aggravation, time and having to undo work just to repeat steps.