They say: "The fastest and most powerful American production sportbike." We say: "At al
Cloaked in gorgeous bodywork by Sharkskinz, it's difficult to resolve the Roehr (say "roar") 1250SC with its Frankenstein-like spec sheet. The 1250cc Harley-Davidson Revolution motor isn't the only repurposed component here. Look closely and you'll spy bits from Ducati, Yamaha, Honda, Suzuki and Buell motorcycles. It's a testament to Gurnee, Illinois-based designer/builder Walter Roehrich's ingenuity and engineering ability that the bike looks so cohesive-and works surprisingly well, too.
Twist the throttle and you'd never guess there's a V-Rod motor lurking inside. Boosted by a belt-driven Rotrex centrifugal supercharger, output is a distinctly non-cruiserish 169 bhp. The supercharger progressively builds to 8 psi of boost at the (conservative) 9100-rpm redline, and is equipped with a bypass valve so the 1250SC acts like any normally aspirated motorcycle off-throttle. Though the slower-revving twin lacks the manic character of a comparable four, the 1250SC's ability to compress time down the front straight at Blackhawk Farms Raceway leaves no doubt this is one very fast motorcycle.
The supercharged V-twin is tall, which made packaging a challenge. The faux fuel tank is actually a cover for the supercharger and battery, while a fuel cell under the tailsection carries a barely adequate 3.2 gallons. Call it mass decentralization. The "bi-metal" frame consists of 4130 chromoly-steel main spars bolted and bonded to billet-aluminum sideplates, built to Roehr's specs by Randy Illg at Framecrafters in Union, Illinois. The single-sided swingarm is fabbed from laser-cut sheet steel. Factory V-Rod rubber motor mounts are retained to quell vibes.
With typical geometry (56-inch wheelbase, 23 degrees rake, 3.5 inches trail), the 1250SC handles like any other sportbike. Steering effort is light, though the bike turns in slowly-likely due to its higher center of gravity. Outright handling was difficult to assess, however, as the pre-production prototype was severely undersprung. The 1250SC pushes 500 pounds, ready-to-ride (the V-Rod motor alone weighs a massive 197 pounds), which is around 50 pounds more than the Ducati 998 that donated the hlins fork or the Yamaha YZF-R1 for which the hlins shock was originally intended. The suspension simply wasn't up to the task, resulting in excessive chassis pitching in both directions that compromised grip-and confidence. Roehrich assured us that spring rates would be corrected on the forthcoming production versions, set for delivery by the end of the year.
Roehrich also hopes to fine-tune the slipper clutch. Calibrated for the longer, much-heavier V-Rod, it allowed the rear wheel to occasionally lock under deceleration. Same for a slight disagreement between the Ducati throttle assembly and V-Rod throttle linkage, which made it difficult to smoothly pick up the throttle mid-corner. These are minor pre-production issues, however, which should prove relatively simple to resolve. The Roehr 1250SC is essentially a coherent and capable machine-especially considering its disparate origins-and one that seems worthy of Roehrich's claim to be "a new American performance legend."