PRO Tharsis XC (+/-6) Stem

PRO Tharsis XC (+/-6) Stem Info

The PRO Tharsis XC Stem is a cross-country handlebar holder that comes with an integrated, external headset adjuster.

The external headset adjuster is a cool fix on its own. This way, you don’t need a star-fangled nut or expander plug inside your steerer tube. You can just put the stem on, push it down on top of the top cap or stack spacers, tighten the steerer tube clamp bolts to the recommended torque (5Nm), and then use the adjuster, a dial under the stem, to take out the play, and secure that.

But the second reason for this is because you can now, if your steerer tube is at over 152mm deep, install a Di2 battery, if you’re running Shimano Di2 shifting, inside the steerer tube (PRO has options for this install, including a clamshell you put around the battery and push into the steerer). A great hiding place, and very easy to service if need be. You won’t have to mess with your saddle position, which is usually far more sensitive than your handlebar position. You can route the Di2 wire through the handlebars, if you have a Di2 compatible bar as well.

Then, there’s the stem itself, which is pretty impressive. 7075 aluminum, with titanium bolts, the 110mm long version comes in at a light 145g. There are stems available in both negative 6-degrees and negative 17-degrees, running from 80-120mm for the former and 70-110mm for the latter. The stem comes with a top cap.

The PRO Tharsis XC Stem gives you the option to hide your Di2 battery inside the steerer.