When you ride your chopper... you're king of the road...


 

 

 


 

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.

 

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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.

 

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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.

 

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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 20 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 28 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 28 to 35-45.  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 " 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 40+ degrees of rake need extra strength built into the neck area, usually with thin metal plates called 'gussets'.

Stock trail was usually around 1-3". 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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