Named after a mountain range on Mars, the PRO Tharsis stem looks more ‘alien mountain’ than all-mountain! Despite its space age looks, the performance is relatively down to Earth.
The big box-section 7075 aluminium unit comes in 10mm steps, from 60mm to 90mm. Despite a sturdy 186g weight for the 90mm, stiffness is decent rather than dramatic, so there’s some flex with a wide bar.
The creak-free stainless steel steerer clamp bolts are round the side away from crashing knees, though, and the broad interlocking four-bolt faceplate spreads the load on carbon bars.