The 1970s: iconic choppers, diggers and Japanese motors

     T

he huge success of the film Easy Rider instantly popularized the chopper, and drastically increased the demand for them. What had been a subculture known to a relatively small group of enthusiasts in a few regions of the USA was now a worldwide wave. The 1970s saw the first wave of European chopper builders, and the "Swedish Chopper" style has its roots in this period.

Custom shops multiplied, and with them the number and diversity of bikes. According to the taste and purse of the owner, chop shops would build high handle bars, or later Ed Roth's Wild Child designed stretched, narrowed, and raked front forks. Shops also custom built exhaust pipes and many of the aftermarket kits followed in the late 1960s into the 1970s. Laws required (and in many locales still do) a retention fixture for the passenger, so vertical backrests called sissy bars became a popular installation, often sticking up higher than the rider's head.

While the decreased weight and lower seat position improved handling and performance, the main reason to build a chopper was to show off and provoke others by riding a machine that was stripped and almost nude compared to the stock Harley-Davidsons andautomobiles of the period. Style trumped practicality, particularly as forks became longer and longer handling suffered. As one biker said, "You couldn't turn very good but you sure looked good doing it."^[9][10]

The Digger became another popular style. Similar to the Frisco choppers Diggers were frequently even longer than earlier bikes, but still low. The coffin and prism shaped tanks on these bikes were frequently mated with very long front ends (12" over stock and more), with the archaic girder fork often being used to accomplish this instead of the more common springer or telescopic types. Body work was also moulded to flow seamlessly, using copious amounts of bondo. New paint colors and patterns included paisleys, day-glo and fluorescent, along with continuing use of metal-flakes and pearls.

Honda's groundbreaking 750 cc four cylinder engine, first introduced to America in the 1969 CB-750, became widely available from salvage and wrecking operations and became a popular alternative to Harley-Davidson's motors. Harley's then-current big-twin motor, the Shovelhead was extremely popular with chopper builders in this era, and use of the older motors, particularly the Knucklehead and Flathead declined as parts became harder to get and the performance of the new motors proved superior.

                                                                                                                       en.wikipedia.com