Carbon rip off (vs Aluminium)

[Christie]

haha' date='

 

to put this in perspective compare the power that will rip the wings off an aeroplane VS the power that a bicyclist will produce... its ridiculous.

 

[/quote']

To compare the amount beer drunk in Gauteng to the amount of rain that fell is also ridiculous

 

all this science is fine' date=' just largely irrellevant to cycling.

[/quote']

 

It sounds like what you are trying to say is "You can still enjoy riding your bike while being ignorant of science behind it." I can agree with that . There is a massive amount of technology behind a bicycle, the chemistry of the paint, the heat treatment of the metal parts, the machining, the matrix, the fibres, the design of the tires etc etc. Very very few people, if any at all, understand all of that. Luckily we dont need to.

Christie2007-11-16 09:12:16

[nellie]

Fair enough Mampara - will maaaaaaaaybe look into that once i paid off my TT wheel (oh ya...that's the only other carbon i own - mavic 3G) but it's still more than 3 times what my normal ones cost.

[Mudsimus]

 

carbon bottle cages - those normal RavX ones (+/-R40??) are a bit heavier' date=' but they're still working while quite a few of my friends have had to replace their carbon goodies (@ around R200 a piece) when the little thingy at the bottom broke off and their bottles are falling through.

 

[/quote']

 

Nellie, here at the 94.7 expo I bought 2 carbon cages from Rapid Sport (the clothing people) They are only 23g ea. Was only R139 ea and they  

 

 

At the OFM they sold it for R120...

[FanieFiets]

 

The frames "going soft" is one of those legends that cycling is built on.  Probably time to let that go the way of some others:

- Smoking before a big mountain opens your lungs;

- Brandy is the on-bike drink of choice;

- Steak for breakfast is the best pre-race meal;

- Red bikes are fastest

 

sh*t, I am on the wrong side of all three! And I am getting a red bike next week........weird.

 

Anway, you guys are saying that the only reason a bike should be replaced is if you get tired of it. Or some new technology (not carbon).

 

[Willehond]

Fanie, watse bike kry jy? VERTEL!!!

[hagar]

ja seker n mooi rooi een om by daai rooi renault te pas

[Johan Bornman]

The frames "going soft" is one of those legends that cycling is built on.  Probably time to let that go the way of some others:

- Smoking before a big mountain opens your lungs;

- Brandy is the on-bike drink of choice;

- Steak for breakfast is the best pre-race meal;

- Red bikes are fastest

 

Linnega, I'm surprised you forgot to mention myths number 1,2,3 and 4, namely.

 

1) On a loaded bike, the hub hangs from the top spoke.

2) A cyclists balances thanks to gyroscopic forces.

3) Tubbies become better when they are first hung up to age.

4) Frames can be still, yet compliant.

 

 

 

[Johan Bornman]

 

FF about fatigue properties: depends on how well it was designed. The fatigue life of the titanium is superior to steel & aluminium' date=' but way, way less than carbon/epoxy. (Dilbert has some SN curves somewhare) I have never analysed a bicycle frame, but I would guess that the stress levels in a frame is very very low most of the time, so comparing fatigue curves is a bit of an academic excersize. I agree completely with JB, a properly designed frame will last forever, regardless of frame material.

[/quote']

 

Your explanation is spot-on, but I just want to add something I've observed with titanium. Titanium frames fail time and again because of heat treatment problems. Although this material should theoretically last longer than alu on a bike, it seldom does, because of the difficultly of manufacturing it correctly. Ti bikes crack at an unacceptable rate.

 

 

I think Ti is an inappropiate material for a bike frame. Aluminium is better in every sense.

 

 

[Johan Bornman]

Carbon is a better material for its unrelenting material properties. Aluminum is subject to age hardening as well as work hardening as well as fatigue. Fatigue is a big concern. Aluminum has an endurance limit as do most materials however' date=' the endurance limit of carbon is considerably higher than aluminum.

[/quote']

 

I don't know what unrelenting material properties are, nor do I understand age hardening. Work hardening is well understood by the bicycle industry and the heat treatment on frames is a very effective remedy. There is no work hardening of alu in a bike's use, only during manufacturing. Fatigue is only al concern on bikes inapproriately designed, manufactured and heat treated. The endurance limit of any material in bike use is a non-issue.

 

[Johan Bornman]

na n rugoperasie (lae rug) is dit nogals erg op n aluminium raam as dit n 100 km reis is. is n harde rit!

het net n vriend se carbon fiets gery' date=' en dit was sagter en hemels vir my rug.so oor watter 1 die beste is sal ons mekaar nie kan oortuig nie,

maar met n rug probleem sal ek al my bonus opgee vir n carbon frame!

[/quote']

 

Ek dink jy het die placebo effect ontdek. Daar is niks in 'n koolstofveselfiets wat beter vering aanbied as 'n fiets van enige ander materiaal nie. Die enigste verskil tussen die twee fietse was die saal en banddruk.

 

Daar is effektiewelik geen vertikale meegee in 'n fietsraam nie en dus geen verskil wat jy kan voel nie.

 

 

[Skillie]

johan, ek glo verseker dat jy baie van fietse af weet,

maar glo dit of nie, carbon gee n sagter rit,

iemand wat nie rug probleem het nie, sal dit nie agter kom nie.

[Kranswurm]

koolstofveselfiets

Boy that took a while to translate.Sounds horrible!

[Johan Bornman]

johan' date=' ek glo verseker dat jy baie van fietse af weet,

maar glo dit of nie, carbon gee n sagter rit,

iemand wat nie rug probleem het nie, sal dit nie agter kom nie.

[/quote']

 

Ek het rug probleme en ek kom dit nie agter nie. Ek ry gereeld staal, aluminium en koolstoffietse en kan geen verskil ander dan 'n akoestiese een waarneem nie.  Maar anekdote vertel nie die verhaal nie.

 

My waarnemings word deur die fisika gestaaf - geeneen van die rame het enige vertikale buiglikheid nie. As dit nie kan buig nie, kan dit nie vering verskaf nie en dus nie sagter of harder voel nie.

 

 

 

 

[_Daemon_]

 

johan' date=' ek glo verseker dat jy baie van fietse af weet,

maar glo dit of nie, carbon gee n sagter rit,

iemand wat nie rug probleem het nie, sal dit nie agter kom nie.

[/quote']

 

Ek het rug probleme en ek kom dit nie agter nie. Ek ry gereeld staal, aluminium en koolstoffietse en kan geen verskil ander dan 'n akoestiese een waarneem nie.  Maar anekdote vertel nie die verhaal nie.

 

My waarnemings word deur die fisika gestaaf - geeneen van die rame het enige vertikale buiglikheid nie. As dit nie kan buig nie, kan dit nie vering verskaf nie en dus nie sagter of harder voel nie.

 

 

 

 

Jammer om te se maar Johan jou fiskika is dan n bietjie af....

You don't have to be able to bend material in order to see if it will provide a softer ride or not...different material absorb vibration better than other, simple example would be how you can hear sound through certain material better than others etc. Carbon absorbs road vibrations better than aluminum, also the reason why steel is such a smooth ride...

Offcourse this all depends on how certain manufactures develop the their frames, so some alu frames might have a softer ride than some carbon frames and visa versa, but if you look at the raw material, carbon WILL give a softer ride...basic physics.

 

[Johan Bornman]

Jammer om te se maar Johan jou fiskika is dan n bietjie af....
You don't have to be able to bend material in order to see if it will provide a softer ride or not...different material absorb vibration better than other' date=' simple example would be how you can hear sound through certain material better than others etc. Carbon absorbs road vibrations better than aluminum, also the reason why steel is such a smooth ride...
Offcourse this all depends on how certain manufactures develop the their frames, so some alu frames might have a softer ride than some carbon frames and visa versa, but if you look at the raw material, carbon WILL give a softer ride...basic physics.
[/quote']

 

You say "steel is such a smooth ride" as if this is fact. I am not so sure this is established. I think most people are brainwashed by stuff they read in bike magazines - aluminium is harsh, steel is smooth, carbon is like triple-ply toilet paper etc etc etc.

 

Since you want to tackle the problem from a vibration and harmonic point of view, lets do that then.

 

Bicycle resonances (vibration, as referred to in these posts) are totally random except for when you drive over something that we can reasonably forsee will give us a specific harmonic - say one of those vibrations strips they now build into yellow lines or a drain grid. Other than that, the frequency is random because the road surface is random.

 

To claim that the frame responds to all of those fequencies is far-fetched. The odd resonation comes from these regularly-spaced purpose-built things on the road. A frame just transmits plain old road shock and doesn't vibrate like a guitar box. The softer your tyres, the less shock reaches you, no matter what type of frame.

 

Further ammo against this vibration argument is the huge damper every bicycle comes with - your body. I once saw a bike gadget salesman demonstrate a damper for handlebars. It was a piece of rubber he inserted - each into one one end of the bar. He dropped the bar and it didn't resonate. He then took the rubber out, dropped the bar and it resonated audibly. I then took the undampened bar, hit is agains the counter and made it resonate. Simply by touching it with a finger, could I stop the resonation. Now imagine how well you dampen it when both hads are clutched around the bar, not to mention the tape, brakes bells and whistles you have on your handlebar.

 

Remember, the resonance of a body is determined by the largest component of the body. A light handlebar cannot resonate when it is dominated by a  pair of heavy arms. Likewise, a silly piece of plastic in a bike's frame cannot stop it from vibrating, the frame is bigger than the plastic. The frame stops vibrating because your body is damping it.

 

The feel of a bike varies from rider to rider and is not something that science can define.

 

An aluminium frame is no harsher than a carbone one. However, undoing years of bicycle magazine damage is difficult to do. Yet, I have never seen a bike magazine define the vibration, determined its frequency and showed the different frequencies of carbon, steel or alu bikes.

 

 

 

 

 

[MintSauce]

I switched from a carbon bar to an aluminium one on my mtb recently and could feel a big difference in the amount of trail vibrations.

 

Care to explain that one Johan?

 

For the first time your posts are really not making sense. I find it ridiculous that you think that different materials would not have a different feel to them or absorb shock differently.

 

So if I make a frame from pvc piping it's going to rid the same as all the steel, carbon and ali frames out there....? That's what your logic iplies....that material makes no difference.

 

I think not. Why don't you guys all do some googling and back up your statements with facts so we can settle this....?