Choppers have enjoyed a large following. Companies like Jesse G. James' West Coast Choppers have been successful in producing expensive traditional chopper-style bikes and a wide range of chopper-themed brands of merchandise such as clothing, automobile accessories and stickers.
A distinction should be noted between true chopper (or chopper-style) motorcycles, and custom motorcycles, or 'custom cruisers'. Despite the name, a large percentage of the motorcycles produced by popular companies such as Orange County Choppers, Indian Larry, Falcon Motorcycles, Warlock Motorcycles, and Von Dutch Kustom Cycles are better described as 'custom' bikes rather than choppers.
A distinction should also be made between choppers and bobbers. While both tried to improve performance by removing any part that did not make the motorcycle perform better, they differed in an important way: bobbers kept the original factory frame, while choppers have a modified form of the factory frame.
When individuals were stripping their stock motorcycles and bobbing their fenders, the term "bobber" was born. When individuals started cutting (or chopping) and welding their frames thereby repositioning/restyling them, the term "chopper" was born. Chopping was the next phase in the evolution that followed dirt track bobbing.
While people assume that the chopper style motorcycles were built purely for aesthetics, there is a real performance advantage to the raked front end on these choppers. These motorcycles have a much more stable feel at high speeds and in a straight line than motorcycles with original factory front suspensions. However, like any other modification, there is a downside: the raked front end feels heavier and less responsive at slow speeds or in curves and turns. This is due to the longer trail measurement associated with increased rake.
Changing the rake and trail of a motorcycle design requires modification of the design itself. This is a job that requires in-depth input from a motorcycle designer who is experienced with such design changes.
Which brings up one more option a chopper builder has: raked trees. Raked trees are designed so the lower tree sticks out further than the upper tree, thus increasing the rake of the forks in relation to the steering head rake. What this does, for those still following along all the imaginary lines, is position the axle closer to the frame rake measurement line, or shortening the trail. Thus, when adding raked trees to a raked frame (which sports a longer trail), the trail is shortened to a more manageable level. However, be warned that adding raked trees to a frame with short rake and trail can be hazardous, as shortening an already short trail measurement can lead to an unstable situation as speed increases. Misuse of raked trees can be quite dangerous, so a bit of research is in order before turning the first wrench on any chopper project. Just remember that because it looks good in a magazine doesn't automatically mean it will work on your bike.
Despite the personalized nature of choppers, and the wide availability of alternative designs, chopper builders have overwhelmingly chosen fat rear tires, a rigid-looking frame (even for a softail), and an original or replica air-cooled, pushrod v-twin engine. In the UK, due to the cost and lack of availability of the v-twin engine, many chose to use British engines from bikes such as Triumph or BSA; lately as availability has increased, Japanese engines have seen more use. Some people feel that the variety of engines and other components used more recently (especially on bikes built outside of the US) is diluting the signature appearance of the chopper style. Modern bobber builders tend to distinguish themselves from chopper builders with bikes styled before the chopper era. Modern bobber builder Jan Bachleda (originally from Slovakia) of JBIKEZ [1]
in Colorado builds custom choppers and bobbers using Triumph engines and frames from the 1970s and earlier. The look, though chopped, is distinctly modern and low. Today's custom choppers are usually seen as center pieces at bike night events around the United States. [
The United States of America, where most custom choppers reside, is one of the few countries in the world that allow custom-built choppers to be licensed for highway use. Many of these types of choppers are regarded as dangerous to operate and don't follow basic design geometry and lack many safety features in their construction.
Finally, an often overlooked style of chopper is the chopper bicycle. Inspired by the smooth, low lines of chopper motorcycles, today's custom chopper bicycle designer builds bicycles that pay tribute to the motorcycles they resemble.
Sunday, June 21, 2009
Chopper (motorcycle)
In the post-World War II United States, servicemen returning home from the war started removing all parts deemed too big, heavy, ugly or not absolutely essential to the basic function of the motorcycle, such as fenders, turn indicators, and even front brakes. The large, spring-suspended saddles were also removed in order to sit as low as possible on the motorcycle's frame. These machines were lightened to improve performance for dirt-track racing and mud racing.
Forward-mounted foot pegs replaced the standard large 'floorboard' foot rests. Also, the standard larger front tire, headlight and fuel tank were replaced with much smaller ones. Many choppers were painted preferably all in either flat black or in shiny metallic “metal flake” colors. Also common were many chromed parts (either one-off fabricated replacements or manually chromed stock parts). According to the taste and purse of the owner, “chop shops” would build high handle bars, or later “Big Daddy” Roth Wild Child’s designed stretched, narrowed, and raked front forks. Shops also custom built exhaust pipes and many of the “after market 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 were 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 such a chopper was to show off and provoke others by riding a machine that was stripped and almost nude compared to the softer-styled stock Harley-Davidsons, let alone the oversized automobiles of that time.
Traditional choppers
In the United States servicemen returning from World War II were looking for a thrill. Many veterans had been trained to work on automobiles and motorcycles and were looking to add a little excitement to their post-war lives with their newly acquired mechanical skills. Motorcycles and Hot Rods were the perfect hobby for them. Motorcyclists bought up surplus military bikes and removed all the unnecessary parts like windshields and saddlebags to minimise weight. Rear fenders were "bobbed" or shortened just enough to handle a passenger and keep the rain and mud coming off the rear, and sometimes removed the mirrors, or replaced them with tiny ones, such as the type used by dentists in their work.
This type of home customization led to the rise of the "bobber". Then in the 60s, motorcyclists found that a longer front end allowed the bike to run smoother at faster speeds. The degree of neck rake and length of front end was modified on these bikes with this in mind. The Girder and Springer front ends were the most popular forks for extending in this fashion, although this does make the bike harder to handle at slower speeds. Nevertheless, some choppers have extremely long forks; as one biker said, "You couldn't turn very good but you sure looked good doing it." [
To build or chop a traditional chopper an unmodified factory bike is used (usually a rigid Harley Davidson) and everything unnecessary to either move or stop is stripped or chopped off. Then the engine and transmission are removed and the frame is cut up and welded back together to make it lower and lighter. Performance parts are added or modified to increase speed.
Forward-mounted foot pegs replaced the standard large 'floorboard' foot rests. Also, the standard larger front tire, headlight and fuel tank were replaced with much smaller ones. Many choppers were painted preferably all in either flat black or in shiny metallic “metal flake” colors. Also common were many chromed parts (either one-off fabricated replacements or manually chromed stock parts). According to the taste and purse of the owner, “chop shops” would build high handle bars, or later “Big Daddy” Roth Wild Child’s designed stretched, narrowed, and raked front forks. Shops also custom built exhaust pipes and many of the “after market 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 were 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 such a chopper was to show off and provoke others by riding a machine that was stripped and almost nude compared to the softer-styled stock Harley-Davidsons, let alone the oversized automobiles of that time.
Traditional choppers
In the United States servicemen returning from World War II were looking for a thrill. Many veterans had been trained to work on automobiles and motorcycles and were looking to add a little excitement to their post-war lives with their newly acquired mechanical skills. Motorcycles and Hot Rods were the perfect hobby for them. Motorcyclists bought up surplus military bikes and removed all the unnecessary parts like windshields and saddlebags to minimise weight. Rear fenders were "bobbed" or shortened just enough to handle a passenger and keep the rain and mud coming off the rear, and sometimes removed the mirrors, or replaced them with tiny ones, such as the type used by dentists in their work.
This type of home customization led to the rise of the "bobber". Then in the 60s, motorcyclists found that a longer front end allowed the bike to run smoother at faster speeds. The degree of neck rake and length of front end was modified on these bikes with this in mind. The Girder and Springer front ends were the most popular forks for extending in this fashion, although this does make the bike harder to handle at slower speeds. Nevertheless, some choppers have extremely long forks; as one biker said, "You couldn't turn very good but you sure looked good doing it." [
To build or chop a traditional chopper an unmodified factory bike is used (usually a rigid Harley Davidson) and everything unnecessary to either move or stop is stripped or chopped off. Then the engine and transmission are removed and the frame is cut up and welded back together to make it lower and lighter. Performance parts are added or modified to increase speed.
Role in modern personal computers
In the book PC 97 Hardware Design Guide,[3] Microsoft deprecated support for the RS-232 compatible serial port of the original IBM PC design. Today, RS-232 is gradually being replaced in personal computers by USB for local communications. Compared with RS-232, USB is faster, uses lower voltages, and has connectors that are simpler to connect and use. Both standards have software support in popular operating systems. USB is designed to make it easy for device drivers to communicate with hardware. However, there is no direct analog to the terminal programs used to let users communicate directly with serial ports. USB is more complex than the RS-232 standard because it includes a protocol for transferring data to devices. This requires more software to support the protocol used. RS-232 only standardizes the voltage of signals and the functions of the physical interface pins. Serial ports of personal computers are also often used to directly control various hardware devices, such as relays or lamps, since the control lines of the interface could be easily manipulated by software. This isn't feasible with USB, which requires some form of receiver to decode the serial data.
As an alternative, USB docking ports are available which can provide connectors for a keyboard, mouse, one or more serial ports, and one or more parallel ports. Corresponding device drivers are required for each USB-connected device to allow programs to access these USB-connected devices as if they were the original directly-connected peripherals. Devices that convert USB to RS-232 may not work with all software on all personal computers and may cause a reduction in bandwidth along with higher latency.
Personal computers may use the control pins of a serial port to interface to devices such as uninterruptible power supplies. In this case, serial data is not sent, but the control lines are used to signal conditions such as loss of power or low battery alarms.
Certain industries, in particular marine survey, provide a continued demand for RS-232 I/O due to sustained use of aging, high-cap-ex equipment. Some manufacturers have responded to this demand: Toshiba re-introduced the DB9 Male on the Tecra laptop. Companies such as Digi specialise in RS232 I/O cards.
As an alternative, USB docking ports are available which can provide connectors for a keyboard, mouse, one or more serial ports, and one or more parallel ports. Corresponding device drivers are required for each USB-connected device to allow programs to access these USB-connected devices as if they were the original directly-connected peripherals. Devices that convert USB to RS-232 may not work with all software on all personal computers and may cause a reduction in bandwidth along with higher latency.
Personal computers may use the control pins of a serial port to interface to devices such as uninterruptible power supplies. In this case, serial data is not sent, but the control lines are used to signal conditions such as loss of power or low battery alarms.
Certain industries, in particular marine survey, provide a continued demand for RS-232 I/O due to sustained use of aging, high-cap-ex equipment. Some manufacturers have responded to this demand: Toshiba re-introduced the DB9 Male on the Tecra laptop. Companies such as Digi specialise in RS232 I/O cards.
Limitations of the standard
Because the application of RS-232 has extended far beyond the original purpose of interconnecting a terminal with a modem, successor standards have been developed to address the limitations. Issues with the RS-232 standard include:
* The large voltage swings and requirement for positive and negative supplies increases power consumption of the interface and complicates power supply design. The voltage swing requirement also limits the upper speed of a compatible interface.
* Single-ended signaling referred to a common signal ground limits the noise immunity and transmission distance.
* Multi-drop connection among more than two devices is not defined. While multi-drop "work-arounds" have been devised, they have limitations in speed and compatibility.
* Asymmetrical definitions of the two ends of the link make the assignment of the role of a newly developed device problematic; the designer must decide on either a DTE-like or DCE-like interface and which connector pin assignments to use.
* The handshaking and control lines of the interface are intended for the setup and takedown of a dial-up communication circuit; in particular, the use of handshake lines for flow control is not reliably implemented in many devices.
* No method is specified for sending power to a device. While a small amount of current can be extracted from the DTR and RTS lines, this is only suitable for low power devices such as mice.
* While the standard recommends a 25-way connector and its pinout, the connector is large by current standards.
* The large voltage swings and requirement for positive and negative supplies increases power consumption of the interface and complicates power supply design. The voltage swing requirement also limits the upper speed of a compatible interface.
* Single-ended signaling referred to a common signal ground limits the noise immunity and transmission distance.
* Multi-drop connection among more than two devices is not defined. While multi-drop "work-arounds" have been devised, they have limitations in speed and compatibility.
* Asymmetrical definitions of the two ends of the link make the assignment of the role of a newly developed device problematic; the designer must decide on either a DTE-like or DCE-like interface and which connector pin assignments to use.
* The handshaking and control lines of the interface are intended for the setup and takedown of a dial-up communication circuit; in particular, the use of handshake lines for flow control is not reliably implemented in many devices.
* No method is specified for sending power to a device. While a small amount of current can be extracted from the DTR and RTS lines, this is only suitable for low power devices such as mice.
* While the standard recommends a 25-way connector and its pinout, the connector is large by current standards.
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