Featherbed frame design went against all engineering princip

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Re: Featherbed frame design went against all engineering pri

I know of ONE 70s TZ750 Yamaha which outhandled the other TZs,H2Rs and RGs in a 1980 round of the swann series. It used a 70s Egli frame. Pat Hennen's TR750 used a Harris frame and was successful - the rest were garbage. The limit of the featherbed is found when the Vincent motor is fitted to one. For a 50BHP 500cc single they are excellent, however every Seeley is better. As far as applying engineering principles to improve motorcycle handling - 'don't tell me - SHOW ME' ! I suggest that every good handling frame ever made has been the result of trial and error. I used to work in large engineering factories in defence manufacturing - I don't believe engineers' bullshit - been around too long for that. They should all be taught about Heisenberg's Uncertainty Principle, they live in a black and white bullshit world.
 
Re: Featherbed frame design went against all engineering pri

Tell me this = how does an engineer interpret the place a riders brain has to be when he is riding a race bike at high speed around a circuit ? The estimation of improvement has to be subjective. If you put a mediocre rider on a superb handling bike, he will immediately become a better rider because the bike inspires confidence. If that rider then adjusts to the bike, he will be even faster. You don't get to become a good rider by riding bad bikes, you just learn how to avoid crashing. Then you need the good handling bike. Better to start with one. That is why so many of the earlier top guys got there after riding those highly developed manx Nortons. I believe every bikey should ride an original one, simply for the experience - a benchmark.
 
Re: Featherbed frame design went against all engineering pri

This is the sort of rubbish you get from the current crop of 1 post wonders.
Gutless wankers posting under fake sign in's that the admin is well aware of.
No need to guess who it is.

Hi Warpy,

just taking a break from having my head stuck up my own arse - but you'll know what that's all about. Thanks for the constructive comments. Good to see you're maintaining the usual high standard on the forum, you do know the main bearings should be NJ not NU? Heh, heh,

Peaky.
Click to expand...

who-has-fitted-superblend-bearings-early-commando-t20664.html
 
Re: Featherbed frame design went against all engineering pri

Now,Now lads! This is going to get locked,,just keep to the issues ..no getting personal.
 
Re: Featherbed frame design went against all engineering pri

john robert bould said:
Now,Now lads! This is going to get locked,,just keep to the issues ..no getting personal.
Click to expand...

Not only that, but 'Warpy' was so steamed up, he posted on the wrong thread !
The superblend discussion is just down the road.
Or really was in a timewarp. ?

LAB should press his delete button ere....
 
Re: Featherbed frame design went against all engineering pri

john robert bould said:
Now,Now lads! This is going to get locked,,just keep to the issues ..no getting personal.
Click to expand...


You are a machinist John, how would you describe to a designer or engineer the feel at the hand wheels of cutting aluminium followed by stainless steel on the lathe, I think it would be impossible.
Constructing a frame would be little different if the designer had no practical skills.

Its a good thread but a little sad that one member has posted in it with two fake ID's now.
I'm waiting for the next new member to Re-revive the worlds 'straightest Commando content in this thread. :lol:
 
Re: Featherbed frame design went against all engineering pri

Rohan said:
john robert bould said:
Now,Now lads! This is going to get locked,,just keep to the issues ..no getting personal.
Click to expand...

Not only that, but 'Warpy' was so steamed up, he posted on the wrong thread !
The superblend discussion is just down the road.
Or really was in a timewarp. ?

LAB should press his delete button ere....
Click to expand...


The new poster Pesky's one post in this thread, try and keep up.
Rohan, I am not steamed up at all, the Yates BS was enough, to many people sat on their hands hoping it would go away.
This is a great site for the main part.
 
Re: Featherbed frame design went against all engineering pri

well i always use power ,but the differance would be motor load? as you know , 303 is a joy. some hi chrome cannot be hand wheeled...pause and "Bang" its work hardened :twisted: Then try to get under the skin!,,silver steel is the same..but back to the post!
Steel structure, build a 100 storey sky scraper ,,one chance. build a bike frame, many chances to put it right..History, the motorcycle went through gradual change most prewar and postwar where straight tubes brazed into iron lugs,,then the feather bed broke the rules. Bent tubes and electric welding.



Time Warp said:
john robert bould said:
Now,Now lads! This is going to get locked,,just keep to the issues ..no getting personal.
Click to expand...


You are a machinist John, how would you describe to a designer or engineer the feel at the hand wheels of cutting aluminium followed by stainless steel on the lathe, I think it would be impossible.
Constructing a frame would be little different if the designer had no practical skills.

Its a good thread but a little sad that one member has posted in it with two fake ID's now.
I'm waiting for the next new member to Re-revive the worlds 'straightest Commando content in this thread. :lol:
Click to expand...
 
Re: Featherbed frame design went against all engineering pri

How about one big egg shaped steel 'tube' be gas and oil tank to mount forks and swing arm on with engine inside suspended in rubber and springs.

Featherbed frame design went against all engineering princip
 
Re: Featherbed frame design went against all engineering pri

hobot said:
How about one big egg shaped steel 'tube' be gas and oil tank to mount forks and swing arm on with engine inside suspended in rubber and springs.
Click to expand...

And a crank handle outside to wind up the rubber band ??

Be interesting to see under that skin, wouldn't it.
 
Re: Featherbed frame design went against all engineering pri

Here is a question - a way for you engineering types to establish your credibility. How are safety factors determined for various materials in various applications, such as welded and monocoque motorcycle frames?
 
Re: Featherbed frame design went against all engineering pri

Same as for most motorcycles ever sold ??
You sell them to the customers, and see how they kill themselves....

In the case of monocoques though, Triumph had an experimental semi monocoque design,
and the Chief Test Rider was killed on it.
Bit like rocket powered space tourists, that was the kiss of death for it.

Welders however have to pass welding tests, and for some industries (submarines and pressure/storage vessels especially)
have to pass regular tests - testing welds to destruction.

I think I previously showed the little steel cube I welded up, and which had to survive a 3000 psi pressure test.
If it had leaked, or burst, it would have been an automatic fail, no possibility of a retest.

Design Rules for vehicles do cover a multitude of aspects of safety and being roadworthy though,
and have to be approved for sale by a number of authorities.
Manufacturers these days can spend gazillions getting things approved, although I don't really know what hoops current
motorcycle makers have to jump through to pass. Imports are easier to get approved than something locally manufactured ??
 
Re: Featherbed frame design went against all engineering pri

Head bean counter is consulted on which materials and how much to accquire then keep making design cheaper till fails to obviously then beef up a bit and get em out the door fast as possible. Racing is similar but simpler of course, come up with napkin idea then fancy-fy it digitally then go out and repair the surprise weakness and over buildt stuff till eventually able to correct more for pilot ability to control its funny quirks. Do enough of this and can chart it into books for reference to show the bean counters. I shudder on occassional flashes of Burt Munroe counting his frame sanding strokes then after some mean recovery time counted a handfull less on next frame, so on for each member for efficient fail safe final frame. Frank Damp has done a good bit of this structural qualifying for Commandos - so mystery remains how the early ones got out w/o the under spine tube. Talk about against all principles, the Commando covers whole scope of em. Trial and error rules the real world. Peels frame now raw state with down tube dents bending stem angle and common spinal curvature so might as well set up to see if worth twisting on. Would be educational to know how much force it takes to tweak stem back in line with vertical or rear iso area.
 
Re: Featherbed frame design went against all engineering pri

Evolution as in "Alter that which failed" untill it doe'snt.





acotrel said:
Here is a question - a way for you engineering types to establish your credibility. How are safety factors determined for various materials in various applications, such as welded and monocoque motorcycle frames?
Click to expand...
 
Re: Featherbed frame design went against all engineering pri

hobot said:
How about one big egg shaped steel 'tube' be gas and oil tank to mount forks and swing arm on with engine inside suspended in rubber and springs.

Featherbed frame design went against all engineering princip
Click to expand...

That wouldn't look so neat with someone sitting on it.
 
Re: Featherbed frame design went against all engineering pri

john robert bould said:
Evolution as in "Alter that which failed" untill it doe'snt.





acotrel said:
Here is a question - a way for you engineering types to establish your credibility. How are safety factors determined for various materials in various applications, such as welded and monocoque motorcycle frames?
Click to expand...
Click to expand...

Aircraft materials are stressed to about 90% of their 0.1% Proof Stress (their elastic limit) , with structural steel common practice is to think of a number and double it (50% of the 0.1% proof stress). With aircraft welding the weld usually has to be 90% of the parent metal tensile strength. So the next question is what standards should be applied to the frames of racing motorcycles ?
My feeling is that if a motorcycle frame does not flex, it will snap unless it is extremely strong. My own bike has a curve chrome-moly tube from the steering head down to the front engine mount. It is was straight, The believe the welds at the ends of it would break. Have a look at the 'ladder' that is used at the front of the standard Mk3 Seeley frame - I'm certain it must always break.
 
Re: Featherbed frame design went against all engineering pri

acotrel said:
john robert bould said:
Evolution as in "Alter that which failed" untill it doe'snt.





acotrel said:
Here is a question - a way for you engineering types to establish your credibility. How are safety factors determined for various materials in various applications, such as welded and monocoque motorcycle frames?
Click to expand...
Click to expand...

Aircraft materials are stressed to about 90% of their 0.1% Proof Stress (their elastic limit) , with structural steel common practice is to think of a number and double it (50% of the 0.1% proof stress). With aircraft welding the weld usually has to be 90% of the parent metal tensile strength. So the next question is what standards should be applied to the frames of racing motorcycles ?
My feeling is that if a motorcycle frame does not flex, it will snap unless it is extremely strong. My own bike has a curve chrome-moly tube from the steering head down to the front engine mount. It is was straight, The believe the welds at the ends of it would break. Have a look at the 'ladder' that is used at the front of the standard Mk3 Seeley frame - I'm certain it must always break.
Click to expand...

What you have written doesnt really make sense, maybe you meant 10% of their proof stress? Even then just using the % of PS is way to simplistic when is it really fatigue we are talking about. Even if a weld is 90% PS for an infinite fatigue life (in steel) you would be aiming for the design stress to be less than 15% of PS (and even then this is a very basic analysis derived from experimental data, not a fracture mechanics approach). That is if you know what the actual loads on the frame are anyway, high and low cycle fatigue as well as none repetitive loads.

Oh, and John have you edited your posts in the other thread so you are not misquoting me?
 
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