Roaring ride through Harley museum (photos)

MILWAUKEE--Sure, other countries build them, but there will always be something uniquely American about the motorcycle. Two wheels and an engine somehow embody a spirit of freedom and rebellion that cars can't always match. As the only surviving American company mass-producing motorcycles, Harley-Davidson looks to keep that free-wheeling, defiant image alive.

To celebrate July 4th July, CNET visited the Harley-Davidson Museum in Milwaukee to get a close-up look at the history of the American motorbike and the spirit that will drive them into the future.

The glowing lines around this early Harley-Davidson prototype motorized bike show the exact dimensions of the first Harley-Davidson manufacturing shop. The wooden walls from the original shack remained in the company's warehouses until a workman threw them away in error.

Though the company started three years earlier, Harley-Davidson incorporated in Milwaukee in 1907, the year this early prototype was made. The early "gray box engine" motorbikes sold for $210 and could travel more than 500 miles on a single tank of oil.

From the earliest days of its creation, the motorcycle seemed perfect for racing. These pre-1910 Harley-Davidson "gray box" bikes raced on a banked wooden track like this one. The outdoor tracks would weather badly and crack, causing constant hazards for racers.

By 1933, the "motorized bicycle" look of Harley-Davidson was long gone, with a design much more familiar to modern motorcyclists taking shape--as in this 1933 V-Twin model.

Designed and built to celebrate Harley-Davidson's 50th anniversary, the 1954 Harley Davidson V-Twin actually debuted in late 1953. Sadly, 1954 also saw the demise of Indian motorcycles, leaving Harley Davidson as the only remaining American motorcycle maker. It remained alone until a British company started making some Indian cycles again on U.S. soil in 2006.

In 1937, this specially built 1936 El Factory Streamliner OHV V-Twin set the then land speed record by hitting just over 136 mph on the hard-packed sand of Daytona Beach, Fla. Its record-setting rider, Joe Petrali, would later move on to help Howard Hughes design the Spruce Goose airliner.

Personalization has always been a big part of owning a Harley-Davidson, as this illuminated wall covered by 100-plus years of individualized fuel tanks chronicles.

In an ill-fated attempt to add to its product line, Harley-Davidson partnered with other manufacturers like AMF to produce snowmobiles, scooters, mini-bikes, and boats. The dabbling almost killed the company, ultimately leading it back to its core identity as a motorcycle maker.

A pioneer for women's motorcycling well into her 80s, Dot Robinson formed the Motor Maids, an international riding club for women, in 1941. She had special lipstick holders like this one forged into all of her motorcycles.

The customized, dazzling chrome work on this 1958 FLH OHV "Uptight" V-Twin Harley Davidson led then chief styling officer Willie Davidson to acquire this bike personally for the company's collection.

The former owner of this Harley-Davidson Electra Glide, Russ Townsend, was a motorcycle community legend for reportedly never stopping the customization of his bejeweled bike, "Russ and Peg's" Rhinestone Harley Davidson.

At more than 13 feet long, the tricked-out and completely customized "King Kong" two-seater shows the outer limits of how far folks will go to personalize their Harley Davidsons. The pipes and other additions are predominantly cosmetic and add nothing to the bike's performance or specs.

Powered by two V-Twin engines, this specially built 1990 OHV Chrome Horse dragster was the first Harley-Davidson to run a quarter-mile drag race in less than eight seconds.

To celebrate the company's 100th anniversary, Harley-Davidson employees past and present signed this specially made 2003 Harley-Davidson Classic Electra Glide touring bike.