Tested: PRO Tharsis Trail Di2 Cockpit

The not-so-minor details


PRO Tharsis Trail Di2


Shimano Australia





Non Di2 bar



Ultimate neatness.
Range of stem sizes.


Fiddly to install.
Headset adjustment requires close attention.

Shimano’s revolutionary electronic shifting is more than just having great shifting gears with zero maintenance. It’s the first step we’ve seen in mountain bike development opening up all sorts of freedom in areas that cables dictate frame design, wires can go anywhere, bending and travelling where cables simply can’t.

Now that is neat, is it not?

What is it?

Pro is Shimano’s component line, with a big range of bars, stems, saddles, wheels and any accessory you would ever need. Working alongside Shimano has its benefits, especially when integrating the XTR Di2 into a dedicated bar and stem, the Tharsis. Available in cross country and the ‘Trail’ series we have here, it’ll cater for any bike between an XC race bike and a big enduro rig.

– The Tharsis Trail series stem comes in four sizes from 35mm up to 65mm. Weights start at 95 grams.

– The Tharsis Trail series bar is available in Di2 specific or regular, 800mm wide with 20mm ride. Weighing 214 grams.

– The bar is available in a non-Di2 option too.

– Full details at PRO website here.

The slim and attractive shifter and brake combo.
The wires sneak into the stem, just under the faceplate there is a gap, designed just big enough for the wires.

How it works.

The whole idea behind the Di2 specific components is to accomodate and hide the electrical wiring for both or just one shifter/derailleur. The wires travel inside the bars, through the stem and into the fork steer tube where the Di2 battery is stored.

The typical star nut assembly that keeps the headset bearings tight is replaced with Pro’s Headlock system, a 32mm cone spanner winds down a threaded collar underneath the stem to preload the bearings. This frees up the inside of the steer tube for the battery to be stashed inside. The battery clips into a cradle that wedges itself securely inside, never a hint of movement is possible with this method.

From the shifter to the computer, the wires travel inside the bar.
Into the stem goes the wire to the battery.
The tiny Di2 battery wedges itself inside the fork steerer tube.
And up and over into the steer tube.
Holes and grooves in the carbon. Whoa.
Holes and grooves in the carbon. Whoa.
Spot the wire?


The installation process is certainly quite fiddly and time consuming when compared to a regular old setup, in fact with all the latest bikes going with internal cable routing in some fashion we are forced to be spending a whole lot more time doing the tasks that were once quite quick and painless. But we all know how nice it is to have a neat bike once its all done, so we put up with it.

Shimano supply a little plastic cable guide tool which can help you guiding the wires through the bars and stem, but we found the best way to save swearing and cursing is using the Park Tools Internal Cable Routing Kit. This little life saving kit will save you so much time and frustration, a worthy investment if you’re often working on internally routed bikes.

The battery cradle that houses it inside the steer tube is a simple and effective, and there’s enough room around the battery to stuff any excess wire inside for extra neatness.

The bars are 800mm wide, unless you’re particularly broad and aren’t bothered by trees in tight singletrack, it’s best to trim them down to suit you best. We ended up at 760mm wide.

Nifty little cap finishes off the clean setup.

We fitted the PRO Tharsis cockpit to a cross country bike too, the Pivot Mach 4. Read that review and see how neat we could make it too – Tested: Pivot Mach 4.

Riding Tharsis

We like the aesthetics of the bar and stem, it’s got a nice feel to it and is very stiff for its weight. The subtle black on black finish adds to the minimal nature of the internal wires to create a very understated look up the front of your bike.

The stem took us a little bit patience though. The Headlock system is a pretty straightforward system but finicky to setup, follow the instructions closely but do crank up the stem bolts slightly higher than the recommended 5NM torque, and we used friction paste on the steer tube for an extra secure grip, or the headset would come loose during rides. Frustrating to say the least early on during testing, but we’ve sorted that out now with the paste and extra torque and it’s remained tight since. We’d not go travelling without the supplied 32mm cone spanner provided though just in case, its not exactly your standard tool found on the everyday multi tool kit.

Neat! And quiet.
Sneaky little wires hiding away.

From your riding point of view its certainly very refreshing to have zero clutter, looking down at your bars you see only your brake and dropper post cables, very tidy indeed.

Quiet bikes are fast bikes.

With rumours of Shimano trickling down their excellent Di2 electronic shifting to lower price points the Tharsis Trail gear will have even more appeal, it takes what we love about no gear cables to another level.

During our long-term review of the Di2, we’ve become accustomed to just set and forget and enjoy the ride, and now with the wires hidden away it’s easier than ever to forget what’s now out of sight.

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