Well this is controversial

[Moon bunny]

Had a strange dream last night....i had bought myself an extremely expensive carbon bike in tasteful dayglo orange....anyhow i was eager to show off to the world my new shiny magnificence so pedalled up by the Loch... but was disappointed that there was no one about...😢 but all was not lost! there was great shaggy highland cow stood in the middle of the single track road " Good morning Mr cow" I said "do you like my splendiferous machine it weighs 10 gms less than my ally one! ..."lovely" said Mr cow, and it only cost £10,000 i excitedly informed him.. " mmm interesting" said Mr cow but i could tell i needed to really impress him! and it has oval tubes so i can go faster! "listen Pal youre really ****ing me off" and before i knew it his pointy handlebar horns had launched me into the Loch!
View attachment 727155

“Mr. Cow”?

 

[Dogtrousers]

“Mr. Cow”?

What a load of bull

 

[Alex321]

“Mr. Cow”?

Anything is possible in a dream

 

[wafter]

“Mr. Cow”?

Are you questioning our uddered friend's self-assigned gender identity?

I'm reporting you to the Guardian..

 

[Dogtrousers]

Anything is possible in a dream

I was in a hotel with an unusual hotel lift the other night. Instead of going vertically up and down a shaft, it moved horizontally through the hotel. And you could see out of it. Apart from that, it was just like a regular lift.

 

[matticus]

I was in a hotel with an unusual hotel lift the other night. Instead of going vertically up and down a shaft, it moved horizontally through the hotel. And you could see out of it. Apart from that, it was just like a regular lift.

Controversial.

 

[T4tomo]

I was in a hotel with an unusual hotel lift the other night. Instead of going vertically up and down a shaft, it moved horizontally through the hotel. And you could see out of it. Apart from that, it was just like a regular lift.

I believe that is called being wheeled down the corridor in a shopping trolley. DAMHIKT!

 

[lazybloke]

Why do you think that is the one advantage of CF?

It's not all about you. What you perceive as advantages might not be relevant to others.

It isn't actually even the main advantage. Though his scenario does eliminate other significant advantages too, by saying they have the same geometry and aerodynamics. Being more easily able to make "tubes" that are not circular in cross section, CF allows different aerodynamic capability.

None of those qualities are unique to CF.

But there is also the directional rigidity, allowing the frame to be stiff but compliant at the same time, and for me as a casual style rider, that is the most important advantage.

That stiffness might be useful if you have the power output of a professional cyclist, but what's the gain for a casual rider like me?

 

[Alex321]

It's not all about you. What you perceive as advantages might not be relevant to others.

Of course it isn't all about me. What a weird reason for saying weight is the only advantage.

And of course those advantages are not relevant to all. But I don't believe very many of the "regular" cycluists who buy CF frames do so only, or even mainly, because of the weight saving. It is a factor, but not that big a factor unless you are a serious racing cyclist.

None of those qualities are unique to CF.

Perhaps you missed where I said "more easily".

Yes, you can make those shapes in other materials, but not as easily, and with more compromise.

That stiffness might be useful if you have the power output of a professional cyclist, but what's the gain for a casual rider like me?

Being able to ride the bike at all. I wasn't suggesting you can make them stiffer in CF than in other materials, and you NEED to have them stiff enough in appropriate directions to be rideable at all.

The point was that you can have the bike flexible enough in other directions to be a more comfortable ride, without compromising that stiffness. On the rough road surfaces we have round here, that makes quite a difference.

 

[Mr Celine]

They blamed the pilot for using too much rudder too fast. That was a total cover up. The control surfaces like the rudder is run by the computer, so either the software in the computer was bad, or the CF vertical tail surface was weak. In either case it was faulty design by Air Bus.

When I used to fly Cessna 150s, several time I slammed the rudder clear to the stop in cross wind landings, and the tail didnt fall off.

According to the wikipedia article on the disaster
https://en.wikipedia.org/wiki/American_Airlines_Flight_587

'The Airbus A300 and later Airbus A310 models do not operate on a fly-by-wire flight control system, but instead use conventional mechanical flight controls'.
The carbon fibre lugs that failed did so under a load of 900kN, more that double their 440kN design limit.

 

[wafter]

The carbon fibre lugs that failed did so under a load of 900kN, more that double their 440kN design limit.

Maybe it's different with aerospace, but a factor of safety of two really isn't a lot!

 

[Jameshow]

Indeed; however it's just the sort of impact that might be encountered if the bike's leant against something and falls over, or something falls against it during storage or transport..

Don't buy a caad 9+ frame or a 853 steel frame and do likewise please!!

 

[matticus]

Maybe it's different with aerospace, but a factor of safety of two really isn't a lot!

I think that's too broad a statement. HGVs have some weight limit - I would expect them to deal with maybe a couple/few hundred kgs over, but you'd be mad to double the "safe" load, and it really should never happen!

 

[Roadrat77]

And none have ever broken ever.

Pinkies crossed.....

 

[wafter]

Don't buy a caad 9+ frame or a 853 steel frame and do likewise please!!

I'd not entertain the idea of a thin-walled ally frame like the CAAD; hardly surprising that the company responsible for this model are often referred to as "crack and fail".

I don't see a problem with 853 - it's heat-treated so will be both hard and tough; so despite the likely thinner wall the tube should have comparable strength to other steels.. and probably still be a lot more resistant to impact and brittle failure than composites.

I think that's too broad a statement. HGVs have some weight limit - I would expect them to deal with maybe a couple/few hundred kgs over, but you'd be mad to double the "safe" load, and it really should never happen!

I guess it depends on application... while it also pays to remember that the factor of safety is not only there to protect against the overloading of a perfect component, but also the underperformance of said component in the event of environmental degradation such as wear, corrosion or damage, as well as tolerances encountered during manufacture.

Having a quick squiz at Wikipedia suggests a FoS of between 1.2 and 4.0 depending on application:

Buildings commonly use a factor of safety of 2.0 for each structural member. The value for buildings is relatively low because the loads are well understood and most structures are redundant. Pressure vessels use 3.5 to 4.0, automobiles use 3.0, and aircraft and spacecraft use 1.2 to 4.0 depending on the application and materials. Ductile, metallic materials tend to use the lower value while brittle materials use the higher values. The field of aerospace engineering uses generally lower design factors because the costs associated with structural weight are high (i.e. an aircraft with an overall safety factor of 5 would probably be too heavy to get off the ground). This low design factor is why aerospace parts and materials are subject to very stringent quality control and strict preventative maintenance schedules to help ensure reliability. A usually applied Safety Factor is 1.5, but for pressurized fuselage it is 2.0, and for main landing gear structures it is often 1.25.[11]