RockShox RS-1 ACS Solo Air 120 (51mm Offset) Fork - 29in - 2017
RockShoxRS-1 ACS Solo Air 120 (51mm Offset) Fork - 29in - 2017

Flip it.

The first thing you'll notice about the RockShox RS-1 ACS Solo Air 120 (51mm Offset) 29er Fork is that its upside-down, tradition-challenging design looks markedly different than other forks out there. While it may be rebellious in looks, this fork packs a whopping combination of stiffness, small bump compliance, rebound recovery, and efficiency that puts many other more traditional-looking forks to shame. The 51mm offset makes for more rake, reducing wheel flop and boosting handling for navigating techy terrain in tight quarters.

The super stiff carbon fiber upper on the RS-1 provides nearly unmatchable stiffness, while the flipped orientation nearly eliminates fork flex for a responsive, snappy feel. This fork also features the firmest lockout of the entire RockShox line, which comes in extra handy when you need every watt to jump out of a corner or sprint past the competition.

Another benefit to the flipped design is smoother stanchion movement across the travel range. The lower stanchion placement takes advantage of gravity's constant pressure, ensuring that the seals are always bathed in oil for friction-free movement. This increases small bump compliance to keep your tire in contact with the trail, providing extra traction to power up over obstacles. Paired with a Rapid Recovery valve that rebounds quickly after full impacts to prepare for the next hit, the fork's inverted design gives you a smooth, controlled ride through even the most jarring terrain.

The RS-1 includes the RockShox Accelerator damping system with Dig Valve compression to fight off bobbing and turn every pedal stroke into forward motion. The Solo Air spring features an easy-to-tune design with a single Schrader valve controlling air adjustment to fill the negative and positive chambers at the same time, resulting in perfectly balanced chambers without any additional tuning. The feel of the spring is customizable in a snap with RockShox's Bottomless Tokens that adjust the chamber volume to dial in the compression curve and meet individual ride preferences.

The RS-1 ACS Solo Air 120 (51mm Offset) 29er Fork is part of the RockShox Predictive Steering system, which utilizes a 27mm Torque Tube axle to further increase the stiffness of the front end. Due to the specificity of this system, the RS-1 is only compatible with the SRAM Rise XX, Rise 60, and Roam 50 29-inch Predictive Steering wheelsets.

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  • Familiarity: I've used it several times

If you can't decide between a sid or rs-1, then choose an rs-1. This fork is great. With the fork inverted it keeps the stanchions proper lubricated. The fork feels great and is smooth. Only downside is that your wheel needs a predictive steering hub. It does however stiffen up the front of your bike and improve handling.