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Chopper Definitions...
This page
is still being added to, so keep cruisin' back for more
good chopper stuff...
On this page...
Birth of the chopper...
Stockers...
Bobbers & choppers...
Front ends...
Handlebars...
Foot pegs...
Rear ends...
Fuel tanks...
Seats...
Exhausts
Moulding
Modifications & equipment...
(Rake, trail, Raked Trees, Stretch, goosenecks)
How safe is the classic chopper...
Copyright... No photos or written material on Choppers
Australia website may be used with out prior written permission...
Birth of the chopper...
Chopper riders like any group, use special
terms when talking about their bikes. We've set this page up
so you know what we are talking about...
The American chopper "style' gained world wide
popularity in the late 1960's and 1970's as a result of a large
number of wild motorcycle movies the most universally impacting of which
was Peter Fonda and Dennis Hopper's "Easy Rider". Vying
for a close second were the earlier movies, "The Wild One"
with Marlon Brando and "The Wild Angels" with Peter Fonda and
Nancy Sinatra.
The Wild One and The Wild Angels
introduced the Hollywood bikie image of dirty jeans, black leather
jackets, cutoffs, outlaw patches and violent pack mentality.
Easy Rider introduced the "Chopper"
and the loner biker as a wandering non violent individual. The
movie and TV series, "Then came Bronson" built positively on this
loner image with the hero stepping in to solve problems a bit like
the classic cowboy.
Choppers Australia is
dedicated to promoting this era, the 60's-70's chopper, so what follows will be
presented from this perspective...
In the sixties (as they still do today) motor
cycle manufacturers made their bikes to suit as many people (and
therefore make as many sales) as possible. The
stock bike made for "Mr Average" just
didn't fit anybody...
Any biker worthy of the name
customises his bike to fit just him (or her) and the 60's-70's were
no different...
Before "Easy Rider", the popular custom route
if you were not into long distance touring with windscreens,
saddlebags etc was the cafe racer.
After Easy Rider choppers became the
predominant custom style.
Stockers...
Harley (What the
chopper originally replaced)... From 1936 Harley Davidson
concentrated on big capacity V twins 1200 and 750cc side valves
(flat heads) and 1000cc and 1200cc overhead valve machines.
The 1000cc (61ci) "Knuckle head" was produced from 1936 to
1947. The 1200cc (74ci) "Pan head" continued on until 1966
when it was superseded by the Shovel head. They were heavy touring
bikes with 5"X16' wheels front and rear often equipped with many
accessories, panniers, crash bars, spotlights and windscreens and
all sorts of pretty baubles that made your bike different to the
rest. This one is a Panhead Duo Glide... (suspension at both
ends) Chopping a Harley made it a whole new bike...
Indian...
Although they ceased manufacture in 1953 Indian Scouts (750cc) and
Chiefs (1200cc) were the only other large capacity American cruiser
and many were chopped through to the early seventies. Their
beautiful girder front end was very popular with Harley chopper
jocks. Indians were in many ways technically superior to
Harleys but the company suffered from frequent bad management
decisions. Without the money to upgrade their venerable
sidevalve motors Indian began to quickly lose ground to Harley once
the OHV Harley Knucklehead got over its teething problems.
Harley Sportster...
Harley's failed attempt to counter the light British twins was a
side valve 750, the model K introduced in 1952 . In 1957 it at
last got overhead valves and though it lacked the nimble handling of
the British bikes, produced its own niche because of its sheer
straight line rubber burning capability. It was popular
chopper material in the US though more expensive to procure second
hand than the big fellow, but a lot of lightening work was already
done...
Triumph (BSA very similar appearance)...
The appearance of the overhead valve fully sprung Triumphs, BSAs ,
Nortons and Royal Enfields in America after WWII rocked Harley
Davidson to its core. Harley had no sports bike to compare and
lost sales to the British makes in a dramatic fashion. In
Australia, British bikes such as Velocette, Royal Enfield,
Matchless, BSA and Triumph (plus numerous others) had been the main
choice available to motorcyclists since the earliest days.
With the chopping craze in the 70's, very few could afford the OHV Harleys, so when it
came to chopping bikes, the British marques were the bikes of choice
until the Honda 750/4, and Yamaha XS650's hit our shores. The
BSA Rocket 3 and Triumph Trident triples, introduced in 1968 and
which set the scene for the Japanese "super bikes" did get
their share of chopping in Europe and USA, but were a bit too
expensive for the Aussie lads to chop...
Honda CB750/4...
Released in 1969, this powerhouse took the biking world by storm... Instant starting,
plenty of power, great acceleration, no oil leaks, no
vibration, reliable. The early ones handled poorly at high
speed and had a tendency to
throw rear chains with some interesting results... damaged housings
and cut legs. A new tool was added to the bikers tool
kit... an impact driver for those pesky sticking Phillips Head
screws the Japs loved using. The CB750 definitely brought
serious motorcycling into the 20th century. It didn't take long for the
chopper fraternity to get into the Honda. Alongside the
Triumph and XS Yamaha, the CB750 was the most chopped Australian bike and some
beautiful examples were created...
Kawasaki Z1... When this monster hit our
shores in 1973 the cocky 750/4 jockeys no longer ruled the roost.
The Z1 with its double overhead cams and 900cc was big, heavy and
very fast. Such brute power available to the street
rider, even more than the CB750, inaugurated the super-bike era.
Being significantly more expensive than the CB 750, very few got
the chopper treatment.
Yamaha XS650...
The Yamaha XS1 hit the market in 1970 and was an instant success,
despite it's atrocious handling. All prior Yamahas in
Australia had been two strokes. It was very popular in
Australia because it looked like the Triumphs and BSA's but
didn't leak oil, was quick and started easily. A great point
in its favour also was that it t looked less Japanese than the
Hondas, as well as being much lighter and slimmer and was quite
affordable. The XS-2 that followed soon after and the later
TX's handled better and had disc brakes and electric starters. The
650 Yams were very popular Australian chopper material as is
evidenced by the large number of yammie choppers "coming out of the
woodwork" in the 21st century. Final factory versions in the
early 80's (like many other brands) got on the band wagon with fat
back wheels and the chopper look.
"Factory choppers"...
Harley's 1971 Super Glide... later become the low rider a model that
runs to this day... Super Glide was a sensation when released
and a stunning change in direction by Harley. It was basically
the big 74 ci Harley with a Sportster front end and was the grand
daddy of factory choppers... Norton, Yamaha and other
manufacturers quickly followed suit with high bars, fat back wheels
and bobbed guards...
Below... Another "factory chopper the Triumph
Hurricane...
Cafe Racer
(classic 60's custom)... This one is a Rickman Honda.
Norton Commandos were also very popular. Rickman was a very
popular manufacturer of Cafe Racer equipment in the 70's. Cafe
Racer has opposite stance to the chopper. The chopper says
"laid back, relaxed, cool" The cafe racer says "focussed,
adrenaline, speed". Cafe Racing lost a lot of ground when the
chopper hit our shores.
Bobbers & choppers...
From its earliest days the motorcycle was modified by its enthusiast
rider... For going faster: speed and endurance races in all
countries were common with in years of the motorcycles emergence.
For carrying on the business: boxes, racks, towbars and sidecars. For
acrobatics: ladders platforms etc. For hunting; gun racks and
pouches, game racks. For travelling; panniers, racks,
leg and wind shields.
Hunting and camping in the 50's... note rifle slung on front bike.
Also tall windscreen on rear bike...
Bobbers and choppers came out of the racing approach.
The introduction of 'C' class racing
by the AMA in 1933 came as a result of the depression with major
bike factories either closing down (Excelsior & Henderson) or
pulling in their purse strings. A & B class for factory racers
was therefore losing momentum, so C class was designed to allow the average Joe to
race his street legal bike with minimal modification. Stripping a
bike to go faster on the track made sense on the street.
Stripped for C class...
Most historians agree that poor job opportunities plus missing the camaraderie and closeness to
death of the battle situation, influenced many returned US soldiers
to turn to motorcycles as a part compensation. The
established motorcycle touring clubs did not appeal to all, so
bunches of war buddies and their mates banded together for a bit
more thrill seeking and out and out hell raising.
There was also much frustration with the mundane and it seemed a
changed and non
understanding society they had fought so hard for and had now
returned to. So for a percentage, venting their anger
and stirring up the
straight citizen became an attractive outlet... what better way than
to break the rules, parade the former enemy's symbols and be what
ever society wasn't.
What ever their attitude, speed and better handling was a high
priority and stripping a bike was a good start. Originally
known as bobtailing (removing rear hinged fender section to look a
bit like the American 'Bobtail cat) the stripped bike generally
became labelled as a bobber...
Bobber... the
bobber usually had standard length forks
and rake, high bars, shorter rear mudguard (often just the hinge pin
pulled out and the rear section discarded), no front mudguard,
small seat and all the 'junk' removed...
The reduced weight
plus straight out pipes were a simple
way to increase speed and manoeuvrability and show yourself apart
from the crowd. This bike and the one below are both
knuckleheads, the first modern overhead valve Harleys. They
were made between 1936 and 1948.
Old school chopper...
was the bobber with narrower front wheel, smaller tank, sissy bar, often a
short fork extension and usually a flashy
paint job. A light and quick handling bike. With all the
stock gear removed, the old school chopper with its straight outs and
better breathing really flew, in comparison to its stock format.
Classic Chopper...
was a phenomenon of the early seventies and very experimental with
some wild designs. Usually had long slim front ends of 10" to
18"extension
(forks were mostly narrowed), raked steering head, lowered rear end
(usually rigid), moulding, fancy point job and lots of chrome.
Paint was generally very bright and multicoloured with a lot of home
jobs done. The variety of styles was quite staggering.
Moulding was often extensive and frequently sculptural.
After
market narrow springers and girders were most popular and dual
square head lights common, Seats were slim, dual seats being most
common as a chick on the back was the order of the day. Cobra
and King/Queen seats were most popular. Sissy bars, often
quite tall and ornate were virtually a requirement. Forward
controls were pretty much mandatory on all makes of choppers.
Petrol tanks were small holding 1-2 gallons which definitely limited
their range, but 'slim' was the cool look.
By the early 70's Americans were
beginning to chop the jap imports particularly the CB750/4 like the
one below.
Digger...
was designed for straight line Freeway drags. Although they
didn't come up with the concept Arlen Ness and his son Cory
popularised the style. Sportster motor (seen here) was the
most popular as it was a naturally quick motor which could stand a
lot of 'hotting up'. Races commonly were between on and off
ramps, so acceleration was premium requirement. Diggers rarely
had sissy bars or pillion seats. Tank on this Sportster is a
diamond tank.. another popular development that followed on from the
coffin tank.
Modern Long Bike...
was a development of the
late 90's, generally long telescopic front forks and rake, often
raked triple trees, very low seat, stretched tank, very fat rear tyre, tendency to
extensive use of billet aluminium parts such as forward controls,
wheels, even swing arms etc. An emphasis on sculptural effect
is achieved more often by the shape and design of parts rather than
moulding as was done on the earlier choppers. There is rarely
space for a pillion passenger (in distinct contrast to the classic
chopper of the 70's) and therefore no sissy bar. Rider
generally leans forward over wide, low handle bars, whereas the
classic chopper jockey sat upright behind high narrow bars.
Cruiser...
Chopper builders can take full credit for this modern style of
stock bike.
Modern Japanese (and every other country's) copy of Harley's
copy of the old school chopper...! Probably the most sensible bike (after
the chopper of course!) on the road. Basically a copy of the
big Harleys with low seats. 70's Harley and chopper riders
really have the last laugh here. We copped all that abuse from
British and Jap riders about our and big back wheels, low seats,
forward foot pegs, backrests and high bars... and big
motors (750 was plenty big enough and V twins... well they were out
of the Ark!) Guess what? Those some blokes have finally
caught up with us 25 years later!
Front ends...
Telescopic forks
(glides)... Introduced soon after WWII the oil dampened
telescopic front fork was a simple effective font end.
Extending them is as simple as having new fork tubes machined and
swapping them with the old (and lengthening a few cables).
They begin to loose their effectiveness at greater than 45 degrees
rake, but do go over curbs better at this angle!. Over about 6"
extension telescopic forks benefit from "tweek bars" (fork
braces) an aluminium bar clamped just above the upper reach of the
fork sliders to reduce twisting of the forks under braking and when
cornering. Owners of classic Harley choppers invariably
narrowed their glides for lightness, their slim look and better
handling. this Harley is a panhead...
Springer...
Standard Harley forks from 1906 (soon after their inception in 1902)
through to 1949 (see the photo of the old school chopper above). Very strong, but bouncy without dampening.
A popular early springer option were
cast forks off the earlier VL which were longer than standard or the
forks from the experimental XA shaft drive, horizontally opposed
desert army Harley which were 4" longer than stock.
Next discovery were Ford radius rods.
These had a similar cross section to the
Harley springer. The springer back legs could be extended by welding
in sections of the Ford radius rod.
Classic choppers usually used narrower and prettier after market
springers like the one in the second photo. Bottom rocker joints need to be kept well
lubricated and tight. Once they wear, the front end becomes
very "loose" and handling suffers.
Springers work at any
angle and handle big bumps and objects on the road better than
telescopic forks.. A springer of the same extension as a
telescopic fork will have less trail because the axle is further in
front of the steering head centre line, a fact not understood by
current Australian legislators with their 550mm steering head to
axle rule...
This motor is a Harley knucklehead. It would have gotten very
hot being all chrome plated. These high bars would have made
handling the bike very difficult and the rider's arms would get very
tired after a few miles on the highway... but the lack of footpegs
and headlight would suggest this photo was taken before the bike was
completed.
In 1941 Harley introduced 16x5 tyres (advertised as balloon tyres
for their soft ride) to replace the 4.50x18 tyres previously used,
so the 18" rear wheel on this chopper may be an original. Most
choppers ran 5x16's (130-16) right through until the 90's when wider
tyres ranging from 180's through to 300's began to gain popularity.
Any rear tyre over 150mm wide while good for straight line riding
are poor handlers in corners and are really not viable if you plan a
lot of miles on your chopper
Aftermarket springers were made by many companies in
the 70's, some good quality many bad. Rocker bushing and
balanced spring rates are crucial to handling. the two sets of
springs on a quality springer will cancel each other's harmonics
and prevent pogo'ing... the development of an ever increasing bounce
usually ending up in a nasty crash. From the 30's onward HD
springers had a friction damper, but chopper riders invariably
removed them to 'clean up ' the front end.
Girders...
Standard European forks until after WWII. The girder was a
popular classic chopper front end and sometimes had friction
dampers. Because of the extra leverage, there is more wear and
tear on a girder's links and they need to be checked regularly.
Top and bottom link should be same length to retain a constant
trail. On this bike, bottom link is longer to lower bike with
artificial rake... definitely not recommended.
Harmon Spurder... This front end was designed by
Bill Harman and patented in 1973. Over 4000 were manufactured
and sold. The company also made frames and forward controls.
It was very rigid and so could handle the stresses encountered
by very long front ends. It was reported to handle much better
than the springers of the time although it did not have damping.
The handle bars were integral with the front end.
This particular chopper had a frame made from Chrome Molly tubing a
very stiff steel alloy, but not easy to weld safely and there was
much debate over its use in bike frames at the time.
Rigid... Uncommon except on show bikes, but was a
fad at one stage. Very 'clean' front end, but with no
suspension very rough unless on very smooth tarmac and definitely
not a handler! If the forks were long enough and the rake
large enough you would get a fair bit of flex in the tubes.
Tweek bars (fork braces)... Clamp just
above slider travel on telescopic front forks to reduce twisting
when cornering etc. A modern form of fork brace clamps across
the top of the lower legs.
Click
to top of page
Handlebars...
Risers... are mounted directly into top triple tree with holes to fit handle bars
and position them higher. This photo shows a combination of
short risers and low W bars. design on tank was achieved using
fish net when painting one of the layers. Fishnet and doyley
effects were popular with home painters.
Dog bones...
mount onto handle bar mounts to raise handle bar height.
Called dog bones because they have a bulge at each end to take 7/8"
or 1" tube. Harley handlebars are 1' while all other bikes
are 7/8". Here are a set of Z bars on standard height dog
bones.
Ape hangers...
Standard bars of the 50's-60's were bent and grips rose about 4"
above mounts. Ape hangers 10", 12" and sometimes more
got the rider's hands up and allowed him/her to sit more upright.
This particular American rider, Indian Larry was until his death in
2004 considered as the US guru of old school choppers. He was
highly respected as a man and as a chopper builder. He was
killed doing one the stunts he was famous for.
Z & W bars...
Getting apes in the early years was not always easy or cheap and
they often only came in one size. Solution? Get some
tube and your welder and make your own. Much easier than
trying to bend tube. W Bars like the ones on this Triumph, bring your hand grips to a nice
comfortable angle (back and down) and release pressure on your
wrists . Drag bars, T bars and Z bars being flatter are less
comfortable than a good set of W's.
T bars... are
flat bars welded to tall risers. By thus replacing the top
clamp with welded joints the rider ended up with a neater set of
bars. In the bad old seventies, using T bars with extended
telescopic forks allowed Honda four owners to quickly return to
stock length when the inevitable defect sticker came along!
Drag bars...
Flat bars previously used on boy racers (cafe racers without the
fairing and rear mounted foot pegs) but on choppers raised up with
long risers.
Pullbacks... Bring your bars back
to allow bent elbows. Quite a different steering sensation.
Less comfortable on your wrists than most six bends...
Six bend pullbacks... Put your
hands in your lap and your wrists at a more comfortable angle than
plain pull backs. Grips on these are unusually steep making
throttle action a tiring.
Foot
pegs...
Forward Controls... Chopper
riders generally like to have their feet stretched forward. On
the original Harleys, this was easy to do... simply removing the
footboards and putting a footpeg (footrest) in the front hole of the
footboard mounting (see below).
The later Sportsters, the English
bikes and later the Japanese bikes were not so easy to do. A place
on the front of the frame (usually the engine mounts) had to be
modified to take a long piece of bar onto which footpegs could be
mounted. Linkages to the gear lever and brake had then to be
made. The complexity of this exercise meant that most 70's
British choppers had mid mounts and Highway pegs, so the controls
did not have to be modified.
Mid Mounts... These were common
on the Sportsters and British and Japanese choppers as that was were
the stock controls already were. For a short time in the early
seventies midmounts were fashionable on the 'Big Twin' Harleys as
well.
Highway pegs... On bikes that
came stock with mid-mounted controls, Highway pegs were the way to
get the stretched out chopper riding position. They did not
have gear or brake levers near them, so were mainly for when the
rider was away form traffic. Sometimes very high highway pegs
were added to choppers that already had forward controls for
not just the look, but also a second foot position for longer trips.
Anderson Pegs...
these were after market folding foot pegs initially to replace the
Harley Floor boards. They came in all sorts of designs, but
with the same square mount. Here are a few, mostly 30 or more
years old.
Rear ends ...
Rigid...
retention of original non sprung rear end common of pre 50's
European and pre 60's American bikes. More comfortable on
heavy bikes with longer wheel base such as Harleys. Can be
pretty rough on British and Jap bikes with only mild fork extension
and standard length rear ends. The entire frame on this
little Honda is home made.
Hardtail...
Adding a rigid section to replace rear swing arm, shockers and rear
frame section. Usually done on British and Japanese bikes.
In the seventies hard
tails could be bought for most makes and either bolted or welded
onto front frame section. This Triumph has had some extra rake
added to its stock steering head. This rear mudguard is a
popular ribbed version which had been used on British bikes for
years. Tank capacity would just get you to the corner store!
Struts...
Replacing the shock absorbers with short struts of solid bar or tube
is a quick, cheap and a simple way of dropping the rear end, losing
weight and getting the chopper look.
Swing arm... Standard
rear suspension from 50's til now. Suspension units usually
shortened or remounted to lower rear of bike. Better handling
offset by higher, heavier and more complex looking bike.
Mounting a sissy bar was also more difficult and rarely as
attractive as running a straight sissy bar off the axle plate on a
rigid bike.
Twin carburetors as on this Sportster was uncommon.
The carbies here are POSA 'injectors'. Lake made a similar
carbie, but they had machined bodies and weremuch more expensive
They had no float bowls, so relied on fuel pressure directly from
the fuel tank. As a result, pressure varied between a full
tank and an almost empty tank, so the mixture would be rich on a
full tank and gradually lean off. For this reason and the fact
that they were very difficult to tune meant they did not remain
popular for long.
Plunger... Axle
is mounted to suspension unit rather than having a weighty swing arm.
Provides better ride than rigid. The advantage over a swing arm is
also easier mounting of a sissy bar but axle travel is limited and
chain tends to "snatch". It was also hard to keep
the wheel from twisting in corners. Most 70's plunger units were
undamped making for a bouncy ride over bumps and poor handling in
bumpy corners.
Soft tail...
Modern combination of rigid look while retaining suspension
introduced by Harley in 1984. Shockers are horizontally
mounted under the gear box. Not a new concept as HRD-Vincent
had same system in the 40's although shockers were under the seat.
Click
to top of page
Fuel tanks...
Peanut... 'cos
it's shaped like a peanut. Like the Sportster tank that follows only
holds about a gallon. This particular tank has also had a hollow beaten
into it and a scorpion set in resin. Contact Choppers
Australia if you want a copy of the article on how to do this for $5
posted.
Sportster...
Tank used on stock Harley Sportsters and very popular on classic
choppers. The sporty tank was taken from the Hummer, a 125-175cc two
stroke built by Harley Davidson the 50's. The early sportsters
had a longer larger tank initially and the Hummer tank was first
introduced on the stripped off road XLCH in 1958 and quickly became
a tank of choice for the chopper builders.
Coffin... Potentially holds more fuel than peanut and Sportster tanks while
still looking pretty trick. An easier tank for the home
builder to make as now complex curves are involved. Invented
by Garry Littlejohn a well know chppper builder in the 70's.
He was also in a lot of chopper movies and was a stuntman for over a
hundred movies.
Diamond...
These followed on from the coffin tanks. Initially
very popular on the diggers of the mid seventies. Quite
popular in Australia. They were very
slim and held less fuel than the Sportster and peanut tanks.
Mustang...
A very popular tank on Harley choppers, this tank originated on the small capacity
Mustang motor cycle, brainchild of William Galdden in 1945.
The 1947 Mustang featured a
single cylinder, 320cc side-valve engine, a three-speed Burman
transmission,.
The BSA Bantam had a similar shape, but with pressed seams across
the top. It has a similar profile, to a peanut tank, but is wider
and holds a
bit more fuel.
Fatbob... these
tanks are original Harley tanks. They were two piece. On the
earlier Harley models and the side valves, one side held oil.
The big speedo and ignition switch were mounted into the top of the
tanks. Disadvantage of fatbobs beside their heavy look is that
the top of the engine is covered, so it is hard to keep clean and
the carby is inaccesable. Fatbobs were considered extremely ugly in the classic
chopper era, but did allow you to travel three times as far between
fuel stops!
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Exhausts...
Drag pipes...
were normally unbaffled straight, short pipes. When adding
shorter pipes to your chopper you will usually need to rejet your
carbies . Shortening your pipes will lean your mixture and
eventually burn your exhaust valves. Twin throat Weber carbie
on this Panhead gets badly in the way of the rider's right leg...
Dumps... were drag
pipes with turned down ends. The pressed metal rocker covers
on this Pan head have been replaced with cast after market covers.
Lights were popular Lucas
Shorty mufflers...
A weight saving and good looking way of quietening your loud
exhausts. A perforated tube usually ran through the
centre of muffler and the space between it and out side casing was
stuffed with fibreglass which had a limited lifespan leading to a
gradual and considerable noise increase.
Upsweeps...
The upsweeps on this Harley panhead have mufflers tipped with fishtails and a sweeter
sound you will never hear... Pillion if you carried one had to
be careful not to touch her right leg on the top pipe.
Bird shooters...
Obvious why they are called this. They were briefly quite
popular. Mixture was richened on
pipes this long and rejetting was required. Pillion needed to
watch where she put her arms. This Triumph has a high backed
King & Queen seat and Sportster tank. It has some rear
suspension vi a Stock 50's Triumph rear 'Sprung Hub'. The
later model hubs recognisable by concentric rings on the side were
apparently more reliable and easier to service
Shotguns...
Another way of getting exhaust out quickly and keeping pipes light
and simple .
Megaphones...
Not the original straight racing megaphones, they were mufflers with
a megaphone shape. They were also called cocktail shakers. These were very popular on Australian
choppers. The ones on this early model Triumph are offset (ie
they turn at an angle to the exhaust pipe). Straight
megaphones were available too. They came with tubular baffles
that were held in place by one 1/4" bolt at the rear. This
bike sports what appears to be an extended Harley springer and six
bend pull backs.
Carburettors...
Info coming
Seats...
Solo pad... for
the solo rider. Springs make for less kidney crushing on those
unexpected pot holes (mandated requirement on every Australian
road) and speed bumps.
Banana...
follows the contour of frame and mudguard. Looks nice and
allows a passenger a modicum of comfort (sort of). This three
pronged sissy bar was a popular classic chopper style.
Cobra... version
of banana seat but with a definite cobra head shape going from wide
seat rails to narrow mudguard. Inlaid colour is nice, but
buttons can be uncomfortable.
King & Queen...
the most comfortable seating. Back support for both rider and
passenger. This seat , covered in fabric is definitely not to
be used in wet weather. The fabric also wears very quickly.
High back...
good comfort for passenger, but if very high like this one can give
a lot of uncomfortable whip especially on a rigid frame. Some
sort of pattern work, bars diamonds and other designs not only look
good, but provide extra grip. Where a lot of stitching is done
as in this example, plastic needs to be placed under seat cover to
prevent entry of rain if the bike is to be ridden in inclement
weather. Piping at join of seat top and side is great for
restricting circulation and not advisable unless you're going to
wear leather pants!
Sissy bar... Not
for sissies. Keeps your lovely lady secure... and happy.
Great for tying stuff to, especially if you are a traditionalist and
like to do every thing on your beloved chop including the weekly
shopping and picking up your oil and new parts.
Click
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Modifications and equipment...
Rake... After long forks, the
most recognisable thing about a chopper is it's raked front end.
Rake is the angle (measured from
vertical) of the steering head.
 
Motorcycles in the 1920's generally
had about 20º rake. This was ok for slow speeds and dodging
pot holes and wheel ruts, but as speeds increased the 'speed wobble'
or 'tank slapper' became a very real problem with many riders ending
up thrown off their wildly gyrating motorcycle! It took a long
time for companies to address the problem properly and even today
many sport bikes are less than stable at speed. Early
solutions were 'steering dampers'... a hand wheel protruding from
the steering head which you tightened once you picked up speed.
You had to remember to loosen it as you slowed down or the stiff
steering would cause to weave alarmingly! A modern version is
a hydraulic damper attached to one fork leg back to a frame tube.
From the 1950's through to the present
time rake increased to around 28º for a standard road bike.
Chopper riders discovered that when
they lengthened their forks or added 21" front wheels their chopper
was more stable at higher speeds. They then cut into the neck
area of their bike's frame and "raked the neck". Common
practice was to increase rake from a standard rake of about 28º to
35-45º. The resulting bike with its much longer forks looked
great and was so stable at highway speed, it felt like it was "on
rails"... and if done properly the speed wobble was never to be
feared again.
In the 70's rake was usually listed as
fractions of an inch the (eg ¼" rake) that the bottom of the
steering head was swung forward after cutting (see A).
A second method of raking the neck
(second Diag )was to cut the front 'down tube' (B) , heat the rear
point of the 'backbone' (at A), stretch the steering head
upwards and weld in 'slugs'. This method had the advantage of
raising the backbone and steering head, giving more space to 'show
off' the engine and also allowed longer forks to be installed.
A raked front end if done accurately and strongly is
much safer than a standard length fork particularly when hitting an
object on the road, not just because of the increased trail, but
also because the spring action will absorb more of the impact
instead of it being transferred to the forks themselves, the frame
and the rider.
Trail... When rake is
increased, trail is increased. The greater (or more 'positive)
the trail, the more resistance the front wheel has to a deflection
such as hitting a brick on the road. The wheel will be
deflected, but its tendency to continue in its original direction
will be stronger than a front end with less trail. This is
called 'castor' on a car and is why on modern cars you don't have to
continually 'steer' the car.. its tends to say in a straight line.
When you reverse however, you will note that the steering wheel then
wants to pull out of your hands to the side. This is an
example of what would happen if your motorcycle had 'negative
trail'.
The two down-sides of increased rake
and trail are heavier steering ('wheel flop') at low speeds and more
stress on the steering head area. Bikes with 40º+ degrees of
rake need extra strength built into the neck area, usually with thin
metal plates called 'gussets'.
Stock trail was usually around 1½-3".
Optimal trail for highway speeds is between 8" and 12". A long wheel based,
heavier bike will handle greater trail than a light short one.
Trail is less for a springer of the same length and rake as
telescopic forks due to the forward set of the axle on a springer.
Australian 550 rule...
Australian Design Rules (ADR's) for motorcycles
specify that the maximum distance forward of the front axle from the
steering head is to be 550mm. This is supposedly to prevent
the long front ends that were so popular with the classic 70's
choppers.
If you are building a chopper, a 40 degree rake with
6" extended telescopic forks will be about the maximum you can do
and still keep within the 550 ADR.
The 550 rule is an unscientific regulation for a
number of reasons. It is not related to wheel base, does
not account for springers and assumes frames are not strong enough
to handle a longer front end than this. It also assumes that
the optimal steering head angle (rake) is that of around 30 degrees
used by sports bikes... great for quick handling around town, but
unstable on the highway especially if the wheel is
deflected by an unexpected object.
550 and the springer... Because the axle
on a springer is about 2" further forward of the steering head line,
a standard length springer on a stock rake reduces an already
minimal trail by a further 2". If the ADR was to be realistic
in "the real world" it should relate to maximum trail and maximum
fork length.
550 and steering head strength... Any modern
(1950's plus) road bike's steering head and frame are quite
capable of handling up to 40 degree rake and 10" extended forks.
Plenty of bikes frames will handle bigger loads still, but it is
worth adding in strengthening gussets over this extension and rake.
Headstem bearings will wear out quicker though and it is advisable
to replace ballbearing races found on 70's Japanese and British
bikes with tapered rollers... and keep a regular check on headstem
conditions.
550 and 'optimum rake'... 28-32 degree rakes
commonly found on road bikes are a compromise to keep the bike light
handling in city streets and easy to bring to a stop at traffic
lights! It is also strongly influenced by racing bikes which
have no real connection with the reality of daily road riding.
40 degree rake with its accompanying trail increase is much safer on
the open road.
550 and fork length...
Telescopic forks of the 70's usually
only had tubes of 32-36mm in diameter and lacked rigidity at
anything over stock length. Any tubes extended over 4" begin
to develop slop (twist) and need a fork brace. When extending
your forks over 6" it is advisable to find a larger diameter set of
forks from a later model bike and adapt them to your steering head.
Springers and more so, girders are
much more rigid than telescopics when extended and should be used
when extending more than 8" .
Raked triple trees... In the seventies
raked trees were a cheat's way of getting the raked "look" with out the expense
of raking your steering head. The angle of the forks are
greater than the angle of the steering post. They reduced
trail often producing negative trail and were extremely dangerous.
Most of the modern long bikes have just enough rake built into the
triple trees to keep trail at around 3-4 inches for the sake of
light steering at low speed .
Stretch... Steering head angle could
also be increased by lengthening the front down tubes to swing the
steering head up and out.
Upward stretch... This yellow Triumph
would have been terrible to ride as front forks are solid (ie no
suspension). Bike is running a standard set of pull backs.
This knuckle head Harley has lots of
forward stretch in the 'Digger' style that originated in the early
seventies. Handle bars are called 'Tiller Bars".
Gooseneck...
A way of stretching your frame with out gaining steering head
height. The first goosenecks (this Panhead was one of the first)
were pretty wild, but modern fabricators are usually more restrained,...
Forward controls...
Forward controls on the 40's Harleys were easy... just throw away
the foot boards, and bolt a foot peg through the front foot board
mounting hole. On European and Jap bikes, forward controls are
a whole different ball game and require solid forward mounted
brackets and quite a bit of fabrication and interesting linkages to
get everything "out there". Transverse Jap fours present the
further problem of having your feet splayed wide and the tendency
(guarantee?) to burn your inner calf muscles on the hot finning!
Still, properly positioned forward controls do make for a much more
relaxed riding position and less fatigue on long distance runs and
is certainly a classic chopper requirement.
Moulding... The
use of body putty (sometimes lead) to smooth out unsightly frame
castings and lumps and to produce smooth flowing lines. This
Triumph is very extensively moulded to produce sculptural effects on
tank, mudguard, frame, rear mudguard stay and tail light. After
some miles of riding cracks would most likely appear around mudguard
stay. Tank looks a part of frame but is actually removable...
Tank has also been dished (hammered in), a common treatment in the
early seventies
This moulding job is
much more basic and used simply to smooth frame casings and
protrusions. This style of moulding not only looks great, but
makes cleaning this Triumph much easier. Megaphones used on
this bike were a very common muffler in the seventies.
Scallops... An
extension of moulding where thin sheet metal often edged with rod is
formed to produce swing raised sections. Scallops were used mainly on tanks
and between converging tubes near the axle on a rigid rear end
. This is a fairly extreme example.
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How safe is the classic chopper...?
All motorcycles are a compromise designed to
cater to the broadest range of rider interest and inexperience.
The classic chopper just like a 'cafe racer', a
tourer, a dirt bike or a drag bike is a purpose built machine.
Like any of these other machines, when a chopper is ridden according
to its purpose... cruising, sedate cornering and straight line
acceleration, it is a very safe and effective design.
The chopper does of
course have "the Look" which to many is much of its appeal, and this
can be its down fall when built for that reason alone, without
thought for proper geometry and structural integrity. Keep in
mind that the sports bike and racing look alikes are built to
achieve "the look" too!
Our comments on chopper
safety obviously are made assuming proper construction and geometry
and obviously discounts some of the wilder show style stuff...
1. What
are the classic chopper's main drawbacks to safety...
a heaviness at speeds below 15 km per hour
which require some extra concentration,
the common
rigid rear end which handles poorly at speed on bumpy corners.,
undampened springers and girders
can give a "disconcerting" ride at
speed in undulating conditions if the spring rates aren't properly
balanced against each other. A common modern dampening
method is to mount a steering damper in front of the springs .
This makes a big difference.
the small narrow
tank does not usually allow the rider to grip it with his knees,
which is a disadvantage in wet slippery or sandy and muddy
conditions.
the feet position does not provide as
much control in slippery conditions.
2. Why a well set up
chopper is much safer than most would think...
Low seat
position...
The chopper's low
seating position (especially on a rigid) also greatly increases
stability, safety and manoeuvrability especially at low speeds and more than
compensates for heavier low speed steering that is due to the extra
trail. Any one who has thrown around a mild rigid chop will
attest to fantastic confidence and ease of manoeuvring with this set
up.
Upright position...
The chopper's upright
rider position gives a better field of view in all conditions than a
sports bike and more steering control when the handle bars are below
shoulder height and not too wide. Putting the rider upright and
further back improves braking safety by putting more weight towards
the back wheel.
The chopper rider in his upright position, tucked into a high-backed
seat is less subject to fatigue on the highway than a sports bike
rider. The tourer's windscreen (not cool on a chopper!)
is an advantage in open road cruising... except in high side winds.
Some wind protection is one reason for the sleeping bag
(poor man's fairing) often seen on choppers out on the highway.
Passenger
position and rider fit...
The chopper passenger has a better field of view (over
the rider's head) giving an added set of eyes for the rider.
She is very secure with a back rest or sissy bar.
If anything on the road is dangerous,
it has to be the pillion set up on many sports bikes... I pity the
poor sports bike passenger perched precariously on a tiny strip of
padding, feet tucked high with no back support. I am
surprised that it is even legal.
The chopper is invariably built to suit its
owner's stature (at least it should be) and is therefore inherently
safer because everything fits like a glove.
Benefits of
increased trail...
The chopper is inherently safer at high speed
than a sport bike because of increased trail, longer wheel base and
lower seating position. After all, if sports bike's steering geometry was
optimal, why would it need a steering damper!!!
Sometimes, chopper
builders aiming for "the Look" without understanding the benefits of
trail, will add rake into the triple trees to bring the trail back
to near stock for light low speed handling. This then only
gives the rider a small advantage in increased wheel base and loses
the all important chopper stability gained from extra trail.
A well set up
chopper front end with its extra trail is a delight to ride at
highway and high speed. The shovel pictured at the top of this
article with its 6" extended front end and 40 degree rake has
been ridden up to 200kph (on the speedo) on a less than perfect
road and it sits on the road like its on rails. A 550 Honda
four ridden by the outhor's son is raked to 45 degrees and has ten
inch extended forks. It is heavy to push around the garage and
steering is heavy up to walking speed, but from then on this chopper
is steady and sure and excellent to ride at highway speed.
Handling in tight corners requires a slightly different technique,
but it is very predictable and easy to put through the 'twisties'.
One engineer once said
to me "Long front ends on choppers are the next best thing to
automobile air bags and should be mandatory" and this is
another good point.
Extra stress on
raked front ends...?
Engineers calculate increased stresses
produced by greater rake and longer front forks and warn against the
danger of broken frames and triple trees. The facts seem
to indicate that sensible welding, gusseting and the tubing sizes
found on motorcycles are more than adequate to cope with these extra
stresses. Stock (but raked ) frames have been ridden consistently
for 20 or 30 years without failure.
Springers do
have benefits...
Critics of the "outdated" springer should also
note that springers handle irregularities found out on the highway
better than telescopic forks despite having less travel. Their
rocker action also retains a more constant trail, a key to handling
in rough cornering conditions... not that chopper riders are into
cornering.
Long wheel
base spells SAFETY...
And the chopper's long front end? The
chopper's long wheel base is a significant safety advantage. The longer wheel base
does makes for slower and different
cornering techniques... but chopper riders are not into road racing
anyway... which increases the chopper jockeys life
expectancy 1000 fold!
The short wheel base of racing bikes
is designed for quick handling and direction changes in a racing
situation. Sports bikes have followed the same design despite public
roads being seriously unsuitable places to race. Even "cruising"
sports bikes with more up right position, screen etc still
compromise open road stability for the "look" and low speed light
handling of the racer.
With a longer the wheel base, the the
rider has more time to correct a sudden change in direction such as
a sliding rear or front wheel due to gravel or an obstacle hit by
either wheel. A number of chopper riders I have personally
spoken to have reported recovering from tricky situations that they
are sure they would not have on their sports bike.
This rider has hit a pair
of 6" and 4" diameter logs on a sharp corner at speed and aside from being
lifted clean off the seat, one twitch of the steering and then
it was on down the road as if nothing had happened. This was because
of the strong self-centring action due to greater rake and trail and
the long (6') wheel base. I
would have been scraping up my skin off the road if I'd had stock
length forks and trail and been sitting on the bike rather than in
it!
Designed for a
purpose...
Sports bikes are set up for quick
cornering not for high speed touring, choppers are set up for
relaxed cruising not fast hills cornering. No one would
dispute that trail bikes are in their element on the dirt but that
their knobbly tires are a hazard in city traffic and on slick sealed
roads. Each design has a different purpose and should not be
compared in each others roles.
General safety...?
When compared with the off road tyres and poor
lighting allowed on "off road" bikes and the inherent
sports bike high speed instability and dangerous lack of passenger
security, the classic chopper fares very well in the safety
stakes.
The classic chopper is definitely a safe design and should not be criticized by the
uninformed or legislated against.
You think this writer is biased? Well
maybe I am, but then again, maybe it's not wise to criticise the
chopper unless you've spent some time riding a well set up chopper built to suit you.
Perhaps you should try it... you just might end up a convert!
Prof...
Seventies chopper builders...
Info coming. US builders... including Denvers
choppers, Bob Hardy, Sugar Bear, Gary Littlejohn, Ron Finch, Arlen
Ness, Amen, Tom McMullen & AEE Choppers, Ed Roth... and some
Australian shops
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