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America’s First Superbike

April 11, 2018
Motorcycles by Crocker

So many what-ifs. But one thing is for sure, Crocker pushed the envelope and developed the most powerful American two-wheeler of its day

 

Al Crocker was born outside of Chicago in 1882, and after graduating from Northwestern University with an engineering degree, he went to work just after the turn of the century for the Thor Motorcycle Company based in Aurora, Illinois. There, he achieved success racing various high-performance Thor V-twin models, in the course of which he formed a friendship with his rivals George Hendee and Carl Hedstrom, the founders of Indian. By 1910, Al was working as a designer and engineer at the Indian Motocycle (as it was originally spelled) Company in Springfield, Massachusetts.

Crocker duly turned his attention to selling the bikes he’d helped create, taking over the Indian agency in Denver, Colorado, in 1913, then managing Indian’s branch office in Kansas City, Missouri. In 1928, he settled in Los Angeles after having acquired the Indian dealership at 1346 Venice Boulevard, which in due course became the Crocker factory. There, Al hired a talented young engineer named Paul A. Bigsby, and together the pair got involved with the sport of cinder-track speedway racing. The company began making frames from 1931 onwards to accept the 750 cc
Indian Scout V-twin engine, and an overhead-valve conversion for the Scout motor soon followed.

But after his V-twin speedway racer’s first season of competition in 1932, Al recognized that a single-
cylinder engine made the most sense for dirt-track racing. So, he developed his own such motor, a 350 cc OHV design around which he built a reputed 31 complete motorcycles between November 1933 and 1936, of which 12 are believed to exist today.

This Speedway single was the first complete Crocker motorcycle, and proved superior to its American rival, the Harley-Davidson CAC. It was, however, slightly down on power compared with the imported British JAP-engined bikes running on alcohol, which would dominate the sport for the next three decades. The Speedway single was thus abandoned, and Al Crocker – already aged 54 – moved on to fulfil another ambition: constructing a class-leading V-twin road bike that would be the fastest thing on two wheels in America, and maybe the world.

 

The Birth of a Legend

Vintage Motorcycles by CrockerAl duly sold his Indian dealership in 1935 to none other than Floyd Clymer (then fresh out of Leavenworth Prison after doing time for mail fraud, who would carve his own particular niche in motorcycle history), then established a 111-square-metre machine shop with a self-contained foundry on Pico Boulevard in L.A. and began work on making that dream a reality. The first Crocker 61 cu. in. V-twin that appeared in 1936 was a joint fruit of the talents of Al and Bigsby, who together created what was then the only American street motorcycle with overhead valves – although unbeknownst to them, the OHV Harley-Davidson Knucklehead was only a few months away from following the Crocker into production. Its 45-degree V-twin engine with exposed rockers and valve springs (later enclosed) established the platform for all future Crockers, with the 61 cu. in.
unit bore and stroke measuring
82.5 x 92 mm.

These were shorter-stroke dimensions than were then fashionable in the U.S., with the OHV engine’s pushrods sharing a common tube, as on the earlier Speedway engines. This gave viewers the illusion that it was an overhead-cam design with bevel-gear camdrive, whereas in fact it was nothing of the kind. Instead, its most advanced technical feature was the use of deep hemispherical combustion chambers with the valves inclined at 90 degrees, and domed pistons delivering a 7.5:1 compression ratio, later raised to 8.5:1.

However, after building the first 17 such engines, Crocker discontinued the hemi design, owing to cracked cylinder heads and poor rocker lubrication, opting for the simpler, less troublesome arrangement of enclosed parallel valves and a flatter combustion chamber for the remainder of production. This sacrifice improved breathing for dependability and greater ease of manufacture, as well as enhanced oil-tightness, and more flexible performance at slower speeds in traffic.

Performance Delivered

Blue Crocker MotorcycleThe original hemi engine had delivered 55 hp at 5,800 rpm, and was safe to a then remarkable 6,700 rpm, which allowed Bigsby to ride one of the first five bikes built out to the 1936 Muroc Dry Lake Speed Trials held in the Mojave Desert near what is today Edwards Air Force Base, where he posted the fastest time of the day by clocking an astounding 206 km/h on a street-legal motorcycle. However, although the parallel-valve models weren’t as blindingly fast, Crocker insisted they were still fleet enough to post a 170 km/h top speed, a claim verified by five Crocker owners who rode their bikes out to the Muroc Speed Trials a year after Bigsby’s feat. They removed the headlamps, and each then clocked over 160 km/h on their respective mounts, before refitting the lights and riding home to Los Angeles with the timing slips in their pockets. This was 16 to 20 km/h faster than either the flathead Indian Scout or new OHV Harley Knucklehead could manage, and even with a milder 7:1 compression, the later Crockers ended up making 48 hp. Compared with a 36 hp Knucklehead motor of identical format, or the larger 32 hp 74 ci Harley VL flathead engine that preceded that, the Crockers delivered performance of a different order.  

But while U.S. motorcycle sales were still floundering in the wake of the Depression – Indian built 5,028 bikes in 1936, rising to 8,883 in 1939, which was 500 more than Harley – a Crocker cost $495 when, due to the economies of scale and in spite of valve-train problems in early engines that dictated a redesign halfway through its first year of production, a top-of-the-line EL Harley with the new Knucklehead engine sold for just $380 – and with a four-speed transmission, at that, rather than a Crocker’s three. So, in order to maintain his motorcycles as a race apart, Crocker responded with the option of ever-larger displacements, since the walls of his cylinders were thick enough to tolerate a hefty overbore, and the bespoke nature of what was always a hand-built motorcycle let him offer engines in capacities up to and even over 72 cu. in.

The Duesenberg of Motorcycles

Red Crocker MotorcycleThe performance and allure of the Crockers earned them the tag of the “Duesenberg of motorcycles,” but unlike his transatlantic counterpart George Brough, the creator of the so-called Rolls-Royce of motorcycles, who relied on high-quality proprietary components to assemble his Brough Superiors, Al manufactured almost everything himself in house, with only items like the Edison-Splitdorf magnetos, Champion spark plugs, Kelsey-Hayes wheel rims and Firestone tires being brought in. Al even started out making his own carbs, before eventually obtaining supplies of a proprietary 1.25-inch Linkert to fit to his bikes.

The reason for this self-sufficiency was that, faced with the threat that the Crocker represented to its investment in creating the new Knucklehead, Harley is reputed to have “persuaded” several suppliers not to meet Crocker’s orders. Among these, the Michigan-based Edward G. Budd Wheel Co. and Kelsey-Hayes Wheel Co. were enticed not to sell their wire wheels to Crocker, so that henceforth Crocker customers were obliged to personally obtain their own wheels and ship them to Crocker for assembly onto their motorcycles! It’s…

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