slimline/slimeline why??

wakeup

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May 1, 2013
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I'm a bit puzzled by the references to slimline frames as "slimeline". I only ever rode one wideline and it was very nice, but to be honest I preferred my slimline 650ss.....
As a onetime Australian politician once said "....please explain"
cheers
wakeup
 
This subject has been covered before and one or two people get rather excited about it.

It has been said that the move from wideline to slimline was a step backward. Some say it was done for comfort reasons. Other say it was to allow the fitting of the enclosures which were in vogue at the time.

Some claim the slimline frame does not handle as well as the wide line.

However two years ago I saw in NZ Classic racing a slimline pass and beat a Manx frame wideline. The bikes had very similar power. The guy on the wideline took two second places at last years Manx Classic, lapping his Manx Norton at over 100 mph. He was the guy that got beaten by the slimline.

I know both bikes very well. One is mine, the other belongs to a friend of 40 years.

So my answer is this.

If you are capable of lapping the Isle of Man at 100 mph then you might be good enough to notice the difference.

If not enjoy your 650 SS which is recognised as one of the best bikes Norton ever made.
 
Can anyone confirm that the steering rake on a slimline is 24 deg as against the wideline at 26 deg.
My recollection of motorcycling in late fifties in the UK was of manufactures trying to literally clean up this form of transport. Imports of the scooter, Lambretta’s, Vespa’s ridden by the Mods showed that motorcycling needn’t be the oil dripping, generally filthy business of the old style Brit bikes.
Even Italian motorcycles had a Heel & Toe gear change that kept the Blue Suede shoes looking good, young men starting to take much more notice of their appearance and using a motorbike for pleasure purposes rather than just daily transport.
So my money is on the styling reason of the change, this I think ties in with era of Triumph’s Bath tub & Velocette’s Veeline etc.
For what its worth.
Craven.
 
In my Norton history book it has a chapter about the history of featherbed frames, the Wideline frames where around for many years of racing, some of the riders were short poeple and complaited that their legs were streched to wide and was uncomfortable on long races, so they made the Slimeline so they could tuck the riders legs in closer to the frame, the 2 frames should handle the same, it will always be the riders ablity and of course how the bike is set up for racing that will make the big diffrents, but I am sure some others will have other ideas, I an just telling it as what is in my book, I don't have the book here at the moment as my mate is reading it at the moment.

Ashley
 
I am almost 100% sure that Ken Sprayson said the critical dimensions of all featherbed frames is exactly the same. The materials and welding method and bend of the top tubes back by the seating area was altered for different years and models, but the rake and dimensions locating the important bits was not.

Two people I know who have built jigs to work on featherbed frames found them all to be the same except they said the very late ones seemed to be manufactured to lower manufacturing tolerances.

The Manx frame was lighter, but the Manx engine is more than heavy enough to make up the difference between a racing and road frame. Plus the Manx engine is top heavy with it's OHC gear.

The Manx frame, with it's larger radius arc in the top tubes down to the swingarm gusset and resulting shorter tube needed, may indeed be a hair more stiff, but in the spirit of what John M said, the best rider is going to do well no matter what he is on.

Kegler's factory racing 88 used a slimline per AMA rules and it came in ahead of Manx Nortons and other real racing machinery often enough to win many races and multiple championships over a 10 year career, also grabbing a real GP point in 67' at the Canadian Gp with the fabulous George Rockett riding behind Hailwood, Duff and Agostini, maybe the only slimline bike to do so?

WWII flying ace Chuck Yeager once stated that the fighter pilot with the most experience would always win no matter what he was flying. He had beat another pilot in mock combat while flying a different type of aircraft, so the other pilot demanded to another try after they switched aircraft, Yeager still came out on top. Same with operating motorcycles or any sort of machine I strongly suspect....
 
beng said:
WWII flying ace Chuck Yeager once stated that the fighter pilot with the most experience would always win no matter what he was flying. He had beat another pilot in mock combat while flying a different type of aircraft, so the other pilot demanded to another try after they switched aircraft, Yeager still came out on top. Same with operating motorcycles or any sort of machine I strongly suspect....
Click to expand...
At a much lower level my first bike was a Y*m*h* XT 250, while a flatmate had the more off road oriented TT 250. As you do at that age we had to have a race from the traffic lights to see if the TT was faster than the XT, it was. We then swapped bikes and had another race from the next set of lights - you guessed it the XT was now the fast one.
I haven't got any faster over the years but hopefully a bit more sensible these days.
 
ashman said:
In my Norton history book it has a chapter about the history of featherbed frames, the Wideline frames where around for many years of racing, some of the riders were short poeple and complaited that their legs were streched to wide and was uncomfortable on long races, so they made the Slimeline so they could tuck the riders legs in closer to the frame, the 2 frames should handle the same, it will always be the riders ablity and of course how the bike is set up for racing that will make the big diffrents, but I am sure some others will have other ideas, I an just telling it as what is in my book, I don't have the book here at the moment as my mate is reading it at the moment.

Ashley
Click to expand...

Slimline frames were road frames, not racers.


Sounds like some book!
 
X-file said:
This might make the slimline look a little bit better,when compared to a 531 wideline frame.Stiffness vs tube wall thickness:[http://www.britbike.com/forums/ubb...ferent discussion than the original question.
Click to expand...
 
I think you could get into trouble with some of those statements - frame stiffness doesn't actually increase with thicker wall thickness - provided you don't make it so thin that the yield point is exceeded. Strength does increase with thickness though.
 
Hopefully,frames never experience forces exceeding yield point.That can happen in an accident;a crash.
Working within the elastic limits,the thick-wall frame flexes less.Elasticity is not proportional to yield strength.High strength and low strength steel tubing is equally elastic,for a given wall thicknesss.
 
Rohan said:
I think you could get into trouble with some of those statements - frame stiffness doesn't actually increase with thicker wall thickness .
Click to expand...


Ah. Actually wrong !

For a tube of given OD increasing wall thickness does increase stiffness. (Youngs Modulus)

The relevent calculations can be found here. Also note the qualifier with respect to Hookes law which is relevent to your yield point comment.


https://en.wikipedia.org/wiki/Young%27s_modulus
 
Triton Thrasher said:
ashman said:
In my Norton history book it has a chapter about the history of featherbed frames, the Wideline frames where around for many years of racing, some of the riders were short poeple and complaited that their legs were streched to wide and was uncomfortable on long races, so they made the Slimeline so they could tuck the riders legs in closer to the frame, the 2 frames should handle the same, it will always be the riders ablity and of course how the bike is set up for racing that will make the big diffrents, but I am sure some others will have other ideas, I an just telling it as what is in my book, I don't have the book here at the moment as my mate is reading it at the moment.

Ashley
Click to expand...
Click to expand...

Slimline frames were road frames, not racers.


Sounds like some book![/quote

Wideline frames were used for road riding bikes as well.
 
johnm said:
For a tube of given OD increasing wall thickness does increase stiffness. (Youngs Modulus)
The relevent calculations can be found here. Also note the qualifier with respect to Hookes law which is relevent to your yield point comment.

https://en.wikipedia.org/wiki/Young%27s_modulus
Click to expand...

Not necessarily.
And thats about as technical or illustrative as a bucket of dirt.

Consider the following statement.

"hollow cylindrical steel pipe deflects significantly less than a round solid steel shaft of the same area carrying the same load.
Rigidity depends both on material and geometrical stiffnesses"
and consider WHY that might be.

Tube stiffness is a very complicated and little understood subject.
You sometimes see quoted that manx frames are less stiff than the roadbikes - were the guys that did them that clueless ?!?
 
If you imagine that the tube was made of rubber,instead of steel,it's not difficult to see that a thicker wall flexes less.
For all practical purposes,below yield stress,both chrome-moly or mild steel are made of the same rubber (their elasticity is almost identical).The "material" part doesn't come into it.

Whether the force is torsional or an applied bending force at the centre of a tube,the amount of flex is inversely proportional to [D (fourth power) - d (fourth power)],where "D" is the outside diameter and "d" is the inside diameter.Doubling the wall thickness almost doubles the rigidity.
In pure compression,the flexibility is inversely proportional to the cross-section area.The thick wall wins again,even more.

Nobody was clueless,but they were practical.A little flex was a good trade off for decreased weight.The thin walled tube was more highly stressed and flexed,so it was made of better material.
 
Its a little more complicated than that.
The bicycle guys report that hi-tensile tubing, if shot-peened and then heat treated, is a lot stiffer than previously.
They say they learned this trick from the motorcycle racing guys ?
Nortons sandblasted their frames, and then stove enamelled them in an oven. Be interesting to talk with someone who worked there ?
The grainflow in metal can also be used to gain 'geometric' stiffness, in some applications.
How does that sit with all steels having the same youngs modulus ??

And, the same amount of steel in a larger (thinwalled) tube is approx 4 times stiffer than the smaller tube.
Surface area here appears to play a (significant) part in this. Or otherwise explain this ?
Thinwall tubing has more internal surface area than thickwall tubing, so its not all clear sailing...?

slimline/slimeline why??
 
I always believed that the 531 type tubing was bronze welded because if it was electric welded it would lose some of its properties making it little or no advantage over a conventional cold drawn mild steel frame that had been electric welded. So the advantage of 531 tubed frame was that it could (should) be lighter with similar stiffness, but at significantly greater cost, both for materials and fabrication.
The slimline was introduced in the late fifties or early sixties. By that time the racing bikes (350 and 500 Manxes) would have been built in very low numbers. The management would have already worked out an end date for Manx production and it would have been simply uneconomic to produce a racing (bronze welded 531) slimline.
cheers
wakeup
 
The Temp. actually induses chrystalynity into the molecular structure . :shock:

The Slimlines got a lot more bends .

Consumer ( :lol: ) resistance to the wide kneed stance astride the widelines ( or Press say so )
was significant in the configureation of the Slimline .

The correlation / similarities in the differant widelines is obvious . The Slimline is a ' Product defined production '
as in its market ( production roadster ) defined its build . It has as many detail differances to the wideline as similarities .

Its over a decade more modern . But only in the ' Road Machine ' context .
 
Rohan said:
The bicycle guys report that hi-tensile tubing, if shot-peened and then heat treated, is a lot stiffer than previously.
They say they learned this trick from the motorcycle racing guys ?
Click to expand...
I would have to say the bicycle guys are misled,and probably measuring yield strength instead of elasticity.It's a common mis-perception that increased yield affects elasticity.
For all practical purpose,the heat treatment makes no measurable difference to elasticity.Sometimes it can be measured,but it's about 0.5% difference and the higher yield strength can be more elastic (lower Young's modulus).
Extreme cold working/work hardening can make a very small difference to elasticity.
Shot-peening only affects the fatigue life,not the stength or elasticity.

FOR ALL PRACTICAL PURPOSE,ALL STEELS HAVE THE SAME ELASTICITY.Chrome moly is slightly more elastic than plain carbon steel,but the difference is small.Operating temperature has a bigger effect on elasticity than anything.
Paint baking temperatures don't amount to heat treatment.You need to get up around 230 C. before you start reducing the hardness and yield strength,even if a part is very hard to begin with.

The area of the inside diameter of the tube and the outside diameter of the tube both have a bearing on the ability to resist bending and torsional flexing.More accurately,it depends on area squared and the difference between inside and outside values.IT'S NOT ROCKET SCIENCE OR MAGIC.
*For a given weight of tube,increasing the inside and outside diameters will help rigidity.There is a limit to how far you can go with this;the tube will buckle easily if it becomes thin like a beer can.
*For a given outside diameter,decreasing the I.D. which means INCREASING THE WALL THICKNESS AND WEIGHT,will ALWAYS INCREASE RIGIDITY.
 
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