Carbon bikes - environmental disaster?

[Duck!]

Speed wobbles are due lack of vibration dampening now? Really? This only gets better!

Yes. I believe your confusion lies in a narrow definition of vibration.

That said, I would normally avoid the term vibration in describing speed wobbles due to confusion with higher frequency harmonic motion (aka 'vibration' that you are referring to) compared to the lower frequency harmonic motion (eg speed wobbles).

Either way there is no need to try to mock me, especially when you fail to grasp the basics.

Make your mind up! Three days ago you told me off for saying basically the same thing you said here! Some consistency to your points would not go astray. You also repeatedly fail to grasp, or maybe selectively ignore context; while you may be correct on a certain discussion point in isolation, you often seem unable to recognise how other factors can affect that point, rendering your argument invalid.

[human909]

rendering your argument invalid.

My argument was simply that low frequency "vibrations" and high frequency "vibrations" are part of the same family. It isn't a complex one nor one that is "invalid".

[fat and old]

Speed wobbles are due lack of vibration dampening now? Really? This only gets better!

Either way there is no need to try to mock me, especially when you fail to grasp the basics.

Bwahahahahahaha Biggest Pot ever calling the Kettle Black

Strong is the irony.

I thought speed wobbles were the result of wearing a helmet, all that messed up airflow?

[Calvin27]

rendering your argument invalid.

My argument was simply that low frequency "vibrations" and high frequency "vibrations" are part of the same family. It isn't a complex one nor one that is "invalid".

Mate you are using your presumably civil engineering knowledge to apply to bicycles. Thereby comparing bridges to bicycles. Pretty invalid in my books. This thread is about carbon bikes. Bridges have no place here, start a new thread maybe?

[duncanm]

Mate you are using your presumably civil engineering knowledge to apply to bicycles. Thereby comparing bridges to bicycles. Pretty invalid in my books.

you seem to be arguing that the laws of mechanics change with scale.

Hint - they don't.

[Calvin27]

Mate you are using your presumably civil engineering knowledge to apply to bicycles. Thereby comparing bridges to bicycles. Pretty invalid in my books.

you seem to be arguing that the laws of mechanics change with scale.

Hint - they don't.

I am arguing that bridge construction/design, loading conditions and maintenance schedules are completely different a bicycle. I don't know of any fully welded, brazed, hydroformed or carbon moncoque bridges, do you?

[duncanm]

Mate you are using your presumably civil engineering knowledge to apply to bicycles. Thereby comparing bridges to bicycles. Pretty invalid in my books.

you seem to be arguing that the laws of mechanics change with scale.

Hint - they don't.

I am arguing that bridge construction, loading conditions and maintenance schedules are completely different a bicycle. I don't know of any fully welded, brazed, hydroformed or carbon moncoque bridges, do you?

I didn't until I googled it just now
https://en.wikipedia.org/wiki/Maurzyce_Bridge

[CXCommuter]

Damn, was hoping to see some sleek new carbon fibre reinforced bridge built by Pinarello

[Calvin27]

Damn, was hoping to see some sleek new carbon fibre reinforced bridge built by Pinarello

Nah they keep changing the design due to changing standards and widths

^ That's the real issue with bicycle longevity imo. No point a frame being robust and lasting if you can't find a BB-right, headshock, brain or any other proprietary part.

[mikesbytes]

Damn, was hoping to see some sleek new carbon fibre reinforced bridge built by Pinarello

Nope, they are too busy trying to sell electric assisted road bikes to female roadies

[P!N20]

Damn, was hoping to see some sleek new carbon fibre reinforced bridge built by Pinarello

It was completed in 1928, all the carbon fibre bridges would have failed by now.

[Comedian]

Damn, was hoping to see some sleek new carbon fibre reinforced bridge built by Pinarello

It was completed in 1928, all the carbon fibre bridges would have failed by now.

Actually... I reckon CF is top stuff. When done well and used in the right application it's magical stuff. I'm not so sure about bridges. And I'm pretty sure that it's more the way we're using it in bicycles that is less than ideal. I've spent many hours in all composite aircraft, some of which were over 30 years old. They were awesome, and very safe. Mind you I knew that if the AC received any bumps it was looked at by engineers, and repaired properly.

From what I can see the problems with CF in bicycles is pretty much as follows.

- Drive to unusual shapes and "styling" forces multi part mold production. Round manufactured tubes offer many advantages but that's not what people want.
- Drive to ultra low weight forces very minimal construction causing very highly stressed structures and very low impact resistance.
- Constant change (Buy the next years model please) means designs aren't properly tested until the users get them. By the time issues are found they have moved on..
- Drive to low cost production means there is limited or no NDT of individual frames, and limited or no testing of whole batches.

If CF bikes were made like aircraft...

- There would be extensive testing and certification of each new frame design
- There would be NDT testing of each frame
- Frames would be made to strict quality.
- Lead times would be epically long, and once made they would produce them for many years without modification.
- I'd be betting they would be a lot heavier and a LOT more expensive. One frame would likely really last a lifetime...

Anyway.. not my problem.

[duncanm]

Damn, was hoping to see some sleek new carbon fibre reinforced bridge built by Pinarello

It was completed in 1928, all the carbon fibre bridges would have failed by now.

Actually... I reckon CF is top stuff. When done well and used in the right application it's magical stuff. I'm not so sure about bridges.

.. CF is increasingly used for concrete reinforcing

[Comedian]

It was completed in 1928, all the carbon fibre bridges would have failed by now.

Actually... I reckon CF is top stuff. When done well and used in the right application it's magical stuff. I'm not so sure about bridges.

.. CF is increasingly used for concrete reinforcing

There are lots of different uses for it.. and many things that it's properties make it ideally suited for. Aircraft manufacturers would very much love to not have to use Ti in their aeroplanes, but there are some things you can do with it that nothing else is suitable for.

https://www.reuters.com/article/us-boei ... PL20150724

[human909]

Actually... I reckon CF is top stuff. When done well and used in the right application it's magical stuff. I'm not so sure about bridges. And I'm pretty sure that it's more the way we're using it in bicycles that is less than ideal. I've spent many hours in all composite aircraft, some of which were over 30 years old. They were awesome, and very safe. Mind you I knew that if the AC received any bumps it was looked at by engineers, and repaired properly.

From what I can see the problems with CF in bicycles is pretty much as follows.

- Drive to unusual shapes and "styling" forces multi part mold production. Round manufactured tubes offer many advantages but that's not what people want.
- Drive to ultra low weight forces very minimal construction causing very highly stressed structures and very low impact resistance.
- Constant change (Buy the next years model please) means designs aren't properly tested until the users get them. By the time issues are found they have moved on..
- Drive to low cost production means there is limited or no NDT of individual frames, and limited or no testing of whole batches.

If CF bikes were made like aircraft...

- There would be extensive testing and certification of each new frame design
- There would be NDT testing of each frame
- Frames would be made to strict quality.
- Lead times would be epically long, and once made they would produce them for many years without modification.
- I'd be betting they would be a lot heavier and a LOT more expensive. One frame would likely really last a lifetime...

Anyway.. not my problem.

Well said.

[fat and old]

It was completed in 1928, all the carbon fibre bridges would have failed by now.

Actually... I reckon CF is top stuff. When done well and used in the right application it's magical stuff. I'm not so sure about bridges.

.. CF is increasingly used for concrete reinforcing

West Gate Bridge, Melbourne

http://www.tandfonline.com/doi/abs/10.1 ... 3.11463904

If you've ever been inside those concrete sections and felt the bounce you'll be impressed!

[human909]

If you've ever been inside those concrete sections and felt the bounce you'll be impressed!

Flex is not something most people associate with big structures.

I particularly like this video:


Start around 5mins if you don't have patience, pause and skip in 10s intevals with the L and J keys you can see the deflection more clearly.

[warthog1]

^^Nup. Not seeing it.
My patience is at an end too.10 mundane minutes
I didn't read your tip until after I'd watched it but I think you need to be an engineer to find it interesting.

[Calvin27]

Flex is not something most people associate with big structures.

You should really start your own bridge thread.

[silentC]

That quote belongs in a different forum actually. Probably one hosted in Russia.

[warthog1]

You should really start your own bridge thread.

Why not?
There are only so many things we can debate before it becomes repetitive and boring.
I can't say I'd have much productive to add (in common with most of my input ) but it would be educational and new to me