For those of us who prefer the responsiveness of four inch XC machines to the predominant trend of slack enduro sleds with six or more inches of travel, forks like RockShox's 27. 5in SID XX Solo Air 100 Fork might feel more and more like a rare treat. Though its aluminum crown and steerer aren't as stiff as their carbon fiber counterparts on the World Cup model, the inclusion of lightweight, 32mm stanchions and the Power Bulge, oversized bushings mean the SID XX is ready to serve as the warhead at the tip of an XC race missile. Though it lacks the World Cup version's carbon bits, the SID XX does include the same race ready Motion Control DNA damping system found in the more expensive model. Fighting off gravity and wallow is in this system's DNA, and it uses external rebound and incorporates separate circuits for low and high speed compression. The damping is remotely adjustable with the included XLoc remote, so you can dial it for high riding sensitivity over consecutive bumps or larger impacts to maintain speed across flats and descents and protect the gap you worked so hard to open up on the previous climb. The Solo Air spring is also easy to tune with a single Schrader valve, which adjusts both the negative and positive chambers at the same time, and RockShox's Bottomless Tokens, which alter the chamber's effective volume to dial in the compression curve and meet individual ramp up preferences. Pairing all this with a Rapid Recovery valve that rebounds quickly after full impacts to prep for the next hit means you'll stay in control across root latticed climbs and rocky descents.