gravel bike rahmen set Open U.P. 2.0 Gravel Chassis

The Open U.P. 2.0 Chassis is the second generation of a gravel frameset that helped define the performance gravel category when the original arrived. Ten years on, OPEN's approach is more refined and more fully developed, but the underlying ambition is unchanged: a fast, light, road-quick-handling gravel chassis that makes the most of every kilometer between asphalt and trail.

The frame is built around a clear design principle OPEN calls "Aero where it matters, comfort where it counts." The front end — headtube, fork, downtube — gets aerodynamic treatment because that's where smooth airflow exists and drag reductions are meaningful. The deep headtube shape is purpose-profiled for aero performance, and the U-Turn Aero fork uses fully aero-section blades with an integrated brake caliper mount that eliminates the standard flatmount adaptor entirely. Moving toward the rear of the frame, the priorities shift. Ultra-thin wire-stays provide compliance, bowing sideways — a geometry change from the first generation, and a deliberate one — to pre-set their flex for better vibration absorption on rough surfaces. The round 27.2mm seatpost continues the same logic: not an aero tube, not an engineered flex member, just a round post with natural compliance and broad compatibility with dropper and suspension posts if you want one.

The OPEN BAR Cockpit

The included OPEN BAR (Break All Rules) cockpit solves a problem most integrated bar-stems ignore: adjustability. The standard tradeoff with a one-piece bar is that fit precision is sacrificed for the weight saving. OPEN's patented internal clamp system adjusts stem length by 15mm in 5mm increments — twice the precision of conventional solutions — without swapping parts and, in most cases, without touching the brake hoses. Because the clamp is internal, the bar remains a fully closed carbon structure with no threaded inserts and no vertical cut through the fiber: continuous carbon for maximum stiffness and the best strength-to-weight ratio. Ten bar sizes run from 380mm to 430mm wide, each with four stem lengths built in, covering a wide range of rider sizes and positions.

Smart Engineering Throughout

OPEN's Smartmount system attaches flatmount brake calipers directly to both the fork and the rear of the frame for 160mm rotors, removing the standard adaptor bracket and its hardware. The result is a lighter, stiffer, more direct caliper interface. Broadshoulder dropouts — 50 to 100% wider than standard — make wheel changes straightforward in conditions where it matters. The T47 threaded bottom bracket shell is 85.5mm wide, accommodating every major crank axle standard without adaptor sleeves. The UDH hanger makes the frame compatible with SRAM Transmission direct-mount rear derailleurs as well as standard drivetrains from SRAM, Shimano, and Campagnolo. Internal routing runs clean throughout the frame. Three rivnuts under the top tube are pre-installed for strapless frame bag attachment, and a WolfTooth chain catcher is included to keep the drivetrain clean on 1x setups.

Geometry, Tire Clearance, and Construction

The UP 2.0 is optimized for tire clearance up to 46mm true width — the performance gravel sweet spot for mixed terrain where speed matters. OPEN's A.I.R. geometry (Agile, Integrated, Refined) is tuned to make the chassis feel as lively as a road bike despite the larger tire volume. Every frame size has its own tube shapes, and every fork size is individually tuned for consistent handling across the range. Head tube angles run from 70° at XS to 72.5° at L and XL; seat tube angle is a consistent 73.5° across all sizes; chainstay length is 425mm in every size. The frame is manufactured in Portugal, weighs 995 grams painted (±3%), and the U-Turn Aero fork adds 390 grams.

The chassis ships complete with the frame, U-Turn Aero fork, OPEN BAR cockpit, headset, 27.2mm seatpost, UDH hanger, WolfTooth chain catcher, integrated computer and GoPro mounts, and noise-reduction foam sleeves. Available at RA Cycles in five sizes (XS through XL) in Farn Green and Sand.