Featherbed frame design went against all engineering princip
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Re: Featherbed frame design went against all engineering pri
To pull this back on topic for a second, if I can...My views are pretty straight forward.
Dr.Steve's claim are pretty much cringeworthy, not because the featherbed wasn't a little dated by the time the commando was rolling out...but mainly because of the end result of what he created. The only real solid defence that exists is simple: if the goal is to produce a road going motorcycle for sale, that would be financially successful, and using mainly existing norton parts...then a featherbed framed bike was not in norton's best interest and would be an awful engineering design choice. At the time Norton had a well developed 360 degree parallel twin that worked well and was capable of being pursued as a modern design. The only catch was that the featherbed with a rigidly mounted 360 twin is a dated design that produces what can only be described as an excessive amount of vibration. Punching the motor out even more and tossing it in a rigid frame would need a lot of thought and maybe even some fundamental changes (indexing the crank to a 270 twin etc...) for it to be a reasonable option, especially compared to what was coming only a year later...realistically, a ground up design was the only thing that made sense. I love the design, think it's a neat idea and a wonderful streetable bike. The frame is a little...agricultural...and the handling is not at motogp levels of tightness...but that was not the goal in mind when developing it. It was to keep a company afloat long enough to make it 4 more quarters! Not every bike is built to be a race replica, most are just built because people enjoy going from point a to point b much faster and with more fun than you'd have in a car!
As for the featherbed itself, it is a dated, flexy design. It was dated and flexy by the time the commando rolled out, and realistically you could throw a stone and hit better frames from numerous makers by the time the early/mid 70's rolled around. Seeley, Egli, etc... come to mind. It was a wonderful design when it came out, and really put most production makers on the right path for the next few decades...but it's not as though technology doesn't progress once it gets kicked in the right direction.
Also at the 750/4 comment from before, it's a little laughable. I've riden on more than one 750/4 based race bike that'll ride the pants off of a similarly prepped norton. A late 70's example in stock shape is quite a different beast, with a big drop in actual power and a little more heft to pull around. Keep in mind that the frame was very capable and was not modified much to make the CR750, the motors were tuned by everyone and their dog, and a RC or yoshi kitted SOHC4 pulls more than hard enough to outdo the frame.
To pull this back on topic for a second, if I can...My views are pretty straight forward.
Dr.Steve's claim are pretty much cringeworthy, not because the featherbed wasn't a little dated by the time the commando was rolling out...but mainly because of the end result of what he created. The only real solid defence that exists is simple: if the goal is to produce a road going motorcycle for sale, that would be financially successful, and using mainly existing norton parts...then a featherbed framed bike was not in norton's best interest and would be an awful engineering design choice. At the time Norton had a well developed 360 degree parallel twin that worked well and was capable of being pursued as a modern design. The only catch was that the featherbed with a rigidly mounted 360 twin is a dated design that produces what can only be described as an excessive amount of vibration. Punching the motor out even more and tossing it in a rigid frame would need a lot of thought and maybe even some fundamental changes (indexing the crank to a 270 twin etc...) for it to be a reasonable option, especially compared to what was coming only a year later...realistically, a ground up design was the only thing that made sense. I love the design, think it's a neat idea and a wonderful streetable bike. The frame is a little...agricultural...and the handling is not at motogp levels of tightness...but that was not the goal in mind when developing it. It was to keep a company afloat long enough to make it 4 more quarters! Not every bike is built to be a race replica, most are just built because people enjoy going from point a to point b much faster and with more fun than you'd have in a car!
As for the featherbed itself, it is a dated, flexy design. It was dated and flexy by the time the commando rolled out, and realistically you could throw a stone and hit better frames from numerous makers by the time the early/mid 70's rolled around. Seeley, Egli, etc... come to mind. It was a wonderful design when it came out, and really put most production makers on the right path for the next few decades...but it's not as though technology doesn't progress once it gets kicked in the right direction.
Also at the 750/4 comment from before, it's a little laughable. I've riden on more than one 750/4 based race bike that'll ride the pants off of a similarly prepped norton. A late 70's example in stock shape is quite a different beast, with a big drop in actual power and a little more heft to pull around. Keep in mind that the frame was very capable and was not modified much to make the CR750, the motors were tuned by everyone and their dog, and a RC or yoshi kitted SOHC4 pulls more than hard enough to outdo the frame.
Re: Featherbed frame design went against all engineering pri
We could quibble a little with this comment ?
The Commando frame came out for 1967, not the early/mid 70s.
And the number of common road bikes that had full double cradle frames in 1967 were still rather thin on the ground,
complete exotica aside. Triumphs, CB450s, XS Yams etc etc so forth and etc again, and myriads of smaller bikes, had
single cradle unsupported steering head frames way past that time, and seemingly sold well in spite of it ?
But, when you study a CB750/4 frame in detail under the steering head, its a liitle more than obvious that
there are shades of featherbed frame tube clusters mixed into that design.
As for CB750/4 motors not being fast, I'd comment that I went for a spin somewhere on a Rickman Onda,
with CB/4 motor slotted into it. Was somewhat surprised to find we were cruising at an indicated 155 mph,
and not even at the redline, no fuss no bother. That fairing and taller gearing worked a treat.
Megacycle cam might have had something to do with it though.
midnightlamp said:
We could quibble a little with this comment ?
The Commando frame came out for 1967, not the early/mid 70s.
And the number of common road bikes that had full double cradle frames in 1967 were still rather thin on the ground,
complete exotica aside. Triumphs, CB450s, XS Yams etc etc so forth and etc again, and myriads of smaller bikes, had
single cradle unsupported steering head frames way past that time, and seemingly sold well in spite of it ?
But, when you study a CB750/4 frame in detail under the steering head, its a liitle more than obvious that
there are shades of featherbed frame tube clusters mixed into that design.
As for CB750/4 motors not being fast, I'd comment that I went for a spin somewhere on a Rickman Onda,
with CB/4 motor slotted into it. Was somewhat surprised to find we were cruising at an indicated 155 mph,
and not even at the redline, no fuss no bother. That fairing and taller gearing worked a treat.
Megacycle cam might have had something to do with it though.
Re: Featherbed frame design went against all engineering pri
Valid comment, sorry that was my bad, I meant to say by the time the mid 70's were roaring...one of those "start a sentance, change you mind, end a sentance forgetting that you started" bits :wink:
But you're right, you definitely see it a lot especially up in the headstock on some full race bikes, but even by the late 60's I'd say many people took the design and ran with it nicely. If you look closely at a bike like the RC181, you'll see a lot of similarities, but definitely a development.
I should be careful though, last time I had this discussion I got in quite a row as I presented from the other side to the other side :mrgreen:
Valid comment, sorry that was my bad, I meant to say by the time the mid 70's were roaring...one of those "start a sentance, change you mind, end a sentance forgetting that you started" bits :wink:
But you're right, you definitely see it a lot especially up in the headstock on some full race bikes, but even by the late 60's I'd say many people took the design and ran with it nicely. If you look closely at a bike like the RC181, you'll see a lot of similarities, but definitely a development.
I should be careful though, last time I had this discussion I got in quite a row as I presented from the other side to the other side :mrgreen:
Re: Featherbed frame design went against all engineering pri
I have no argument with Tex. I respect his opinions, they are always very good. The discussion was about thermodynamics and probably a bit out of place here. It's strange that culture actually has an effect on scientific theory. Those two systems, the American and the British both end up in the same place however the reasoning is inverted. That is why what Tex said in his posts seemed unusual to me.kerinorton said:
Re: Featherbed frame design went against all engineering pri
I rode the CB750 Honda when they first came to Australia. It was quiet, didn't leak oil or rattle, however it handled like a camel. I remember one race meeting when the CB750s first appeared and I rode my 500cc Triton weaving through them in a cloud of water, going miles an hour faster. It didn't last for long because the guys discovered the CB450 pistons would fit if they drilled bigger holes making the motor 830cc, then it was a different story. At about the same time Bill Patterson Honda bought a CR750 which was a convincing argument when ridden by Tony Cacciotti, however Frank Mussett's Triumph 650 Bonneville and his 750cc Trident were both much faster around Calder Raceway with Peter Allen riding them. I only ever saw one commando racing back then. It was owned by S.R.Evans and ridden by Geoff Curley. It actually won a few races, however Geoff would win on anything.
I rode the CB750 Honda when they first came to Australia. It was quiet, didn't leak oil or rattle, however it handled like a camel. I remember one race meeting when the CB750s first appeared and I rode my 500cc Triton weaving through them in a cloud of water, going miles an hour faster. It didn't last for long because the guys discovered the CB450 pistons would fit if they drilled bigger holes making the motor 830cc, then it was a different story. At about the same time Bill Patterson Honda bought a CR750 which was a convincing argument when ridden by Tony Cacciotti, however Frank Mussett's Triumph 650 Bonneville and his 750cc Trident were both much faster around Calder Raceway with Peter Allen riding them. I only ever saw one commando racing back then. It was owned by S.R.Evans and ridden by Geoff Curley. It actually won a few races, however Geoff would win on anything.
Re: Featherbed frame design went against all engineering pri
i was just surprised that a frame with such a stellar background and history could ever be described as
then again, i think dude was ~ new to bikes, nevertheless, did wonders with the commando for road use which imo, was definitely the way to go
i was just surprised that a frame with such a stellar background and history could ever be described as
then again, i think dude was ~ new to bikes, nevertheless, did wonders with the commando for road use which imo, was definitely the way to go
Re: Featherbed frame design went against all engineering pri
I read a paper years ago on motorcycle handling which came from the Society of Automotive Engineers. After I distilled a conclusion out of all the garbage it came down to one thing - 'we don't know what we are talking about'. You can have all the engineering theories and apply them and still come up with a dud. What the McCandless brothers did was find a practical solution to a very difficult problem. The closest other answer to it was the Vincent frame, and it really got nowhere near being a good answer. The commando frame seems OK for a road bike, however the first production version had race steering geometry and a few novices got chucked up the road after riding over 'cats' eyes'. I suggest that vice is always there waiting with the isolastic frame. If I had to choose between a commando engine mounted in a featherbed frame or a commando frame for racing, I would always choose the featherbed. (For me it would be the difference between staying upright or crashing). However for just bumming around on public roads the standard commando is probably quite adequate, and a bit of comfort in a road bike is always nice. I don't ride on public roads because it does my head in with the sheer frustration of it. I had a very bad childhood.
84ok said:
I read a paper years ago on motorcycle handling which came from the Society of Automotive Engineers. After I distilled a conclusion out of all the garbage it came down to one thing - 'we don't know what we are talking about'. You can have all the engineering theories and apply them and still come up with a dud. What the McCandless brothers did was find a practical solution to a very difficult problem. The closest other answer to it was the Vincent frame, and it really got nowhere near being a good answer. The commando frame seems OK for a road bike, however the first production version had race steering geometry and a few novices got chucked up the road after riding over 'cats' eyes'. I suggest that vice is always there waiting with the isolastic frame. If I had to choose between a commando engine mounted in a featherbed frame or a commando frame for racing, I would always choose the featherbed. (For me it would be the difference between staying upright or crashing). However for just bumming around on public roads the standard commando is probably quite adequate, and a bit of comfort in a road bike is always nice. I don't ride on public roads because it does my head in with the sheer frustration of it. I had a very bad childhood.
Re: Featherbed frame design went against all engineering pri
About 'engineering principles'. Tell me this - where is the paper from a professional body on safety, which relates the effects motorcycle steering geometry to engine power characteristics and gearing, when the motorcycle is to be used on a race circuit ? The MotoGP guys are obviously well up with this stuff, however their MotoGP Workshop videos on Youtube stay well away from the subject. We have lots of smart engineers about, surely they must have a clue about what is involved ? Perhaps their education is incomplete ?
About 'engineering principles'. Tell me this - where is the paper from a professional body on safety, which relates the effects motorcycle steering geometry to engine power characteristics and gearing, when the motorcycle is to be used on a race circuit ? The MotoGP guys are obviously well up with this stuff, however their MotoGP Workshop videos on Youtube stay well away from the subject. We have lots of smart engineers about, surely they must have a clue about what is involved ? Perhaps their education is incomplete ?
Re: Featherbed frame design went against all engineering pri
googled norton commando vs featherbed handling, not much came up
2 post thread here from 07
commando-featherbed-frame-t1754.html
6 post thread 05
featherbed-commando-frame-t751.html
then came across this
http://seeleynorton.com/technical/q-and-a
googled norton commando vs featherbed handling, not much came up
2 post thread here from 07
commando-featherbed-frame-t1754.html
6 post thread 05
featherbed-commando-frame-t751.html
featherbed-commando-frame-t751.html#p5519
then came across this
http://seeleynorton.com/technical/q-and-a
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Re: Featherbed frame design went against all engineering pri
I don't know the answer to your question about where the white paper on the engineering principles you desire to learn about is...
But I am pretty certain it won't be on Youtube... !
acotrel said:
I don't know the answer to your question about where the white paper on the engineering principles you desire to learn about is...
But I am pretty certain it won't be on Youtube... !
Re: Featherbed frame design went against all engineering pri
Have you had a look at the MotoGP Workshop videos on Youtube ? They are very interesting, however what they stay away from is even more interesting.
If you have a look at this particular video, the guy talks about what is critical however doesn't mention the relationship between what changing the settings does and the general effect on the handling/steering. If you read Tony Foal's stuff it mentions that reducing the trail on a bike can move the handling more towards self steering, and I suggest that increasing the trail moves it towards mishandling under brakes. In the end the steering geometry must be set to balance between power output, tyres and frame stiffness, and whether you want the bike to naturally tighten it's line in corners or to run slightly wide for safety.
https://www.youtube.com/watch?v=aHVFS8e3cRY
Rohan said:
Have you had a look at the MotoGP Workshop videos on Youtube ? They are very interesting, however what they stay away from is even more interesting.
If you have a look at this particular video, the guy talks about what is critical however doesn't mention the relationship between what changing the settings does and the general effect on the handling/steering. If you read Tony Foal's stuff it mentions that reducing the trail on a bike can move the handling more towards self steering, and I suggest that increasing the trail moves it towards mishandling under brakes. In the end the steering geometry must be set to balance between power output, tyres and frame stiffness, and whether you want the bike to naturally tighten it's line in corners or to run slightly wide for safety.
https://www.youtube.com/watch?v=aHVFS8e3cRY
Re: Featherbed frame design went against all engineering pri
Why? Featherbed steering head is braced to the cylinder head and the engine plates are bolted to the same frame gussets as the swing arm is.
I'm not sure what this thread is about. if you're worried about handling differences between Dominators and Commandos, ride the bikes and make a judgement.
Nothing can go against all engineering principles!
84ok said:
Why? Featherbed steering head is braced to the cylinder head and the engine plates are bolted to the same frame gussets as the swing arm is.
I'm not sure what this thread is about. if you're worried about handling differences between Dominators and Commandos, ride the bikes and make a judgement.
Nothing can go against all engineering principles!
Re: Featherbed frame design went against all engineering pri
The difference between a commando and a featherbed frame is a matter of necessity. You can fit an 850 motor into a featherbed frame and it would be excellent if you raised the balance factor, which you must if you want to rev it beyond about 2000 RPM. You then have bike which cannot be ridden slowly. So why would you build a bike like that if you want to use it on public roads ? The 750cc Atlas motor stretched the capability of the featherbed frame to it's limit because the motor is rigidly mounted. The Commando frame with the isolastics barely gets there as an answer. When a bike relies on it's head steady for it's handling - that is dangerous bullshit.
The difference between a commando and a featherbed frame is a matter of necessity. You can fit an 850 motor into a featherbed frame and it would be excellent if you raised the balance factor, which you must if you want to rev it beyond about 2000 RPM. You then have bike which cannot be ridden slowly. So why would you build a bike like that if you want to use it on public roads ? The 750cc Atlas motor stretched the capability of the featherbed frame to it's limit because the motor is rigidly mounted. The Commando frame with the isolastics barely gets there as an answer. When a bike relies on it's head steady for it's handling - that is dangerous bullshit.
Re: Featherbed frame design went against all engineering pri
'Nothing can go against all engineering principles!'
I suggest the comment about going against all engineering principles was probably made be a fairly young engineer. If you look at a featherbed frame, a Seeley frame is obviously superior because of the tubes which run from the steering head to the pivot, and the construction around the pivot. However the Seeley frame came along about 15 years later when we knew more about how to make a bike handle. Some of these kids who come along and get fed bullshit by lecturers often believe they know a lot. If you want to test what I am saying, take a fistful of dollars along to a consulting engineer who hasn't raced a bike, and pay him to design a monocoque frame for you. You can have all the 'engineering principles' yet build an absolute dud bike. Engineers often live in a black and white world, with everything done by plugging numbers into an algorithm. Bikes are not like that, when you race one you are always juggling about 6 variables and that falls into the realm of pattern recognition.
'Nothing can go against all engineering principles!'
I suggest the comment about going against all engineering principles was probably made be a fairly young engineer. If you look at a featherbed frame, a Seeley frame is obviously superior because of the tubes which run from the steering head to the pivot, and the construction around the pivot. However the Seeley frame came along about 15 years later when we knew more about how to make a bike handle. Some of these kids who come along and get fed bullshit by lecturers often believe they know a lot. If you want to test what I am saying, take a fistful of dollars along to a consulting engineer who hasn't raced a bike, and pay him to design a monocoque frame for you. You can have all the 'engineering principles' yet build an absolute dud bike. Engineers often live in a black and white world, with everything done by plugging numbers into an algorithm. Bikes are not like that, when you race one you are always juggling about 6 variables and that falls into the realm of pattern recognition.
Re: Featherbed frame design went against all engineering pri
The Seeley frame looks to have more rigidity in the relationship between the swing arm and the steering head.
It's probably better than the Featherbed frame in some situations. Taking my 42 bhp roadgoing engine out of its Wideline and putting it into a Seeley is not likely to show an improvement that I can discern.
Putting a 900cc Jap racing four into a Featherbed frame is probably a silly mistake.
acotrel said:
The Seeley frame looks to have more rigidity in the relationship between the swing arm and the steering head.
It's probably better than the Featherbed frame in some situations. Taking my 42 bhp roadgoing engine out of its Wideline and putting it into a Seeley is not likely to show an improvement that I can discern.
Putting a 900cc Jap racing four into a Featherbed frame is probably a silly mistake.
Re: Featherbed frame design went against all engineering pri
Maybe not the most elegant ever engineering, but used by the one-time World top racing bike and also by tens of thousands of road bikes.
"Dangerous bullshit" it was not.
acotrel said:
Maybe not the most elegant ever engineering, but used by the one-time World top racing bike and also by tens of thousands of road bikes.
"Dangerous bullshit" it was not.
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