PRO Tharsis XC Seatpost

PRO Tharsis XC Seatpost Info

The Tharsis XC Seatpost is the lightest MTB post PRO has to offer. They’ve taken the lessons they learned working with carbon fiber and applied them to the needs of cross-country riding.

The shaft is made of unidirectional carbon-fiber and PRO shows off their work with a matte finish. This is long, light, and strong, as the top of the shaft wraps over the seatpost clamp, securing it to the rest of the post. They’ve finished the bottom of the post with a bias, the front side being longer than the back side. This saves weight. It’s not much, but it’s a real savings and it reflects their desire to only have the minimum material necessary.

The clamp is a one-bolt round clamp that expands against the round top. It’s easy to precisely dial in your preferred seat angle, and hold it. The relatively narrow clamp also makes it easy for you to push your saddle far back or far forward, depending on your needs. Because the side-clamp needs to be precise to hold your seat in place, the post comes with two clamps, one for 7x7mm rails, one for 7x9mm rails.

There is one length, 400mm. There are three available diameter options: 27.2, 30.9, and 31.6mm. There are two setback options, 0mm and 20mm.

The post is also Di2 battery compatible. Batteries typically come with a few mounting sleeves, washers, and circlip mounts. You use these to solidly hold the battery in the post.

The Tharsis XC Seatpost is a no-nonsense ultralight seatpost at 199g for the 27.2mm diameter version.