Carbon rip off (vs Aluminium)

[Johan Bornman]

 

You obviously do not have any idea what you are talking about. You are comparing a City Golf to a M3 BMW. Rather find out why there are price differences before you start talking k@k about something.

 

Your contribution to what was an otherwise intelligent discussion, is not really useful.

 

Perhaps you can explain to us why we are not comparing apples with apples. You seem to have a lot of insight and knowledge on the subject.

 

 

[Skillie]

meeste aluminium rame het nou carbon vurke , seat & chain stays.

dink julle dat alles oor 5 jaar carbon gaan wees?

dan gaan daar rerig nie plek v my ou Le Jeune wees nie.

[Johan Bornman]

meeste aluminium rame het nou carbon vurke ' date=' seat & chain stays.

dink julle dat alles oor 5 jaar carbon gaan wees?

dan gaan daar rerig nie plek v my ou Le Jeune wees nie.

[/quote']

 

Daar is 'n baie goeie rede waarom meeste vurke deesdae koolstofvesel is. 'n Vurk is een van die mees kritiese komponente op 'n fiets. As dit breek, sien jy vir Elvis.

 

Jy sal oplet dat vurke min of meer, direk van staal na koolstop gegaan het, sonder die tussengang van die metale wat ons tot vandag toe op fietse sien naamlik aluminium en titaan. Die rede hiervoor is dat staal 'n baie goeie vurkmateriaal is vanwee sy onbeperkte weerstand teen metaaluitputting as dit onder 'n sekere punt gebuig word. Aluminium en tot 'n mindere mate, titaan is baie swakker in hierdie opsig.

 

Metaal in die ou dae was die enigste materiaal wat geskik was vanwee die feit dat die vurk 'n skroefdraad in die boonste buils verlang het en net metaal kon dit doen.

 

Daar was 'n periode waar aluminium en titaan probeer is, maar dit was 'n katastroefiese flop.

 

Die deurbraak het gekom met die sogenaamde Aheadset, wat nie 'n skroefdraad verlang nie en koolstof het onmidellik sy plek daar gekry. 

 

Verder, die hoeveelheid maatskappye wat vurke vervaardig is baie minder as die wat rame vervaardig, omdat dit 'n spesialisproduk is wat jy nie wil vekeerd kry nie.

 

Dis dus goedkoper om 'n goeie koolstofvurk te vervaardig as een of ander hibriede metaal een. Bv, alu kan glad nie vir die "Steerer tube" gebruik work nie, dit sal breek en net bokant die vurk kroon. Titaan kan gebruik word, maar is nie maklik om te verwerk in die vorm van 'n elegante vurk nie. Dit raak net te duur om te doen.

 

Om 'n half metaal, half koolstofvurk te maak, is nogal moeilik en dus word die ding een slag gemaak, alles van koolstof.

 

Staal is uit die mode uit en nogal swaar in 'n vurk, so dit laat net koolstofvesel oor en dis wat ons vandag het. Staal word nog suksesvol gebruik in bergfiets vurke - natuurlik ongeveerde vurke.

 

Ek voorspel dat koolstoffietse nie gaan domineer nie en een of ander mode sal weer ingryp. Daar is nogal 'n tendens om koolstof en metaal te meng, ons sien baie alu/koolstof en Ti/koolstoframe op die mark. Dis maar 'n modegier en het geen ingenieursrede nie.

 

Ek weet nie hoe fietse oor 10 jaar gaan lyk nie maar ek weet hulle sal duurder wees, nog steeds draadspeke gebruik, nie 14 ratte per kasset he nie en hopelik geen elektronika he nie.

 

 

 

 

 

 

 

[GIRR]

the impression im getting from this alu vs carbon argument is that theres actually little differences between the two.

 

I have both an alu bike and a carbon bike and when riding the same routes definitely (excuse the word) "feel" like the road is less rough, as well as the dead feeling you get from having a puncture on the rear wheel is the same as my carbon bike at normal pressure yet the carbon bike is more responsive as well in terms of how it accelerates (same wheel sets on the two bikes).

 

Now im not sure if anyone could explain this to be other than being due to the different materials used?

 

[Mudsimus]

I've also recently switched from a full alloy bike to a full carbon bike. There is definatly a huge differance, and no science bla bla bla is going to convince me otherwise.

[Johan Bornman]

the impression im getting from this alu vs carbon argument is that theres actually little differences between the two.

I have both an alu bike and a carbon bike and when riding the same routes definitely (excuse the word) "feel" like the road is less rough' date=' as well as the dead feeling you get from having a puncture on the rear wheel is the same as my carbon bike at normal pressure yet the carbon bike is more responsive as well in terms of how it accelerates (same wheel sets on the two bikes).

Now im not sure if anyone could explain this to be other than being due to the different materials used?
[/quote']

 

The difference is accoustic, in other words, the sound the bike makes. Put in earplugs and try again. It is difficult to ascertain what we want here in a scientific way, but try and keep an open mind.

 

As for the responsiveness, well, firstly what does responsiveness mean? YOu attempt at defininig it by saying it accellerates differently. The only difference you can have with accelleration is either better or worse. And since a bicycle accellerates like a snail - 0-30kph in about 30 seconds for a reasonable rider - it is difficult to detect even a 10% improvement. Besides, there is nothing in the physics of the two bikes that make them accellerate differently. The engine is the same, the wheels are the same (you say) and thefore the only difference is the mass of the frame (nothing else on a frame other than mass affects accelleration.). If we thus look at the mass difference - say 1kg, we can calculate that given the same power, the 80 and 81kg package will accellerate only a small fraction differently, something that is measureable but not perceptible.

 

I think you're fooling yourself to believe what you want to believe because of the cost or other emotions you attach to the two bikes.

 

 

[greatwhite]

I've also recently switched from a full alloy bike to a full carbon bike. There is definatly a huge differance' date=' and no science bla bla bla is going to convince me otherwise.

[/quote']

 

I have both carbon and ali road bikes - both same manufacturer, identical geometry - the carbon bike is about 2kg lighter and definately a better race bike (I'm not sure about its longenvity), but it should be, the frame is 10 times the price and fitted with all the latest gizmos.

 

The reason I started this post was to get folks to think before just assuming carbon better for everything:

 

If you get a 900g carbon frame like a cervelo R3 or scott CR1, then you are maybe getting a decent deal, because there are no ali frames that light. But what about the 1.2-1.3kg carbon frames (and there are plenty of them) compared to a signifcantly cheaper ali frame weighing the same? Would you not be wiser spending your hard earned cash on the cheaper frame then get better equipment for it?

 

[GIRR]

I think you're right there with the sound and emotional/mental side to the different frames

 

Is it possible perhaps that also as you are paying far more for the carbon frame that more design and research has gone into it making it a more efficient frame?  otherwise there would be no difference between buying similar weighted BMC, Cervelo, Trek, Raleigh etc... frames...here comes a war of the brands

 

[Christie]

I've found an article on the www of a German (not surprising?) cycling magazine that tested 41 current 2007 frames. They measured mass of frame & fork, lateral stiffness of the bb and vertical stiffness of the rear dropouts (more deflection = more comfort, according to them) to use the combined results determine the best frame. Among the frames included in the test were the Cervelo R3, Scott Addict, C'dale System6, Pinarello Paris, Giant TCR Advanced, Look 595, Merida Scultura & Ridley Noah, and a old C'dale CAAD 9 as a reference. They had no steel frames in the test.

On the comfort rating (vertical stiffnes of rear dropout - I think), some interesting findings:

#1 Specialized Roubaix, 169 N/mm (meaning it takes 17.2 kg to displace the dropouts verically by 1mm)

#3 Giant TCR advanced, 196 N/mm

#6 Felt F1, 210 N/mm

#8 Cervelo R3, 223 N/mm

#9 C'dale CAAD9, 232 N/mm ( 23.6 kg for 1mm displacement)

 

The old CAAD9 was measured less harsh than lots of other full carbon frames, and very very close to the Cervelo R3. To me, this is a good indicator that carbon does not provide comfort as believed by many, and JB has a point about the placebo & acoustic effects carbon.

 

Worst comfort was the Ridley Noah.

 

 

 

For Hubbers who want to look at the article, & can read German:

http://www.tour-magazin.de/to/tour_artikel//show.php3?id=2286&subnav=21&nodeid=25

The full article with all the test data costs 2 euro. I tried to buy it, but the  wont accept my SA credit card without me phoning them first. I would really really like to have the test data

Christie2007-11-21 12:07:58

[Johan Bornman]

I've found an article on the www of a German (not surprising?) cycling magazine that tested 41 current 2007 frames. They measured mass of frame & fork' date=' lateral stiffness of the bb and vertical stiffness of the rear dropouts (more deflection = more comfort, according to them) to use the combined results determine the best frame. Among the frames included in the test were the Cervelo R3, Scott Addict, C'dale System6, Pinarello Paris, Giant TCR Advanced, Look 595, Merida Scultura & Ridley Noah, and a old C'dale CAAD 9 as a reference. They had no steel frames in the test.

On the comfort rating (vertical stiffnes of rear dropout - I think), some interesting findings:

#1 Specialized Roubaix, 169 N/mm (meaning it takes 17.2 kg to displace the dropouts verically by 1mm)

#3 Giant TCR advanced, 196 N/mm

#6 Felt F1, 210 N/mm

#8 Cervelo R3, 223 N/mm

#9 C'dale CAAD9, 232 N/mm ( 23.6 kg for 1mm displacement)

 

The old CAAD9 was measured less harsh than lots of other full carbon frames, and very very close to the Cervelo R3. To me, this is a good indicator that carbon does not provide comfort as believed by many, and JB has a point about the placebo & acoustic effects carbon.

 

Worst comfort was the Ridley Noah.

 Cut cut cut....

 

 [/quote']

 

It would have been nice to see the test data and test methodology.

 

But lets assume that they load the seatpost collar on the frame to get to a deflection at the drop-out.

 

I find it strange that the stiffest bike was considered the most comfortable. There's an anomoly.

 

Anyway, lets go to the stiffest frame, the Specialized Roubaix,  which requires 17.2 kg to displace the dropouts verically by 1mm. Since is made from a Hookean material (I think, anyone help me out here?) another 17,2 kgs will deflect it another 1mm and so on. For a 70kg rider therefore, it deflects roughly 4mm and by hitting a bump, some 16mm. That's a lot! I can't reconcile with that figure, unless it was a long seatpost and they loaded it from the saddle position and therefore there is some seatpost deflection in there.

 

Maybe the Germans are still going to shake my world.

 

Comments anyone?

 

 

[Christie]

JB, as I have it, the Roubaix was #1 on the comfort scale because it needed less force than the others to displace a certain distance. They interpreted this as beign the most comfortable, thus having the lowest vertical stiffness.

 

I cant read enough German to figure out exactly what their test configuration was. Possibly clamped the BB & headset, applied a known verical load to the dropout & measured the deflection.

Christie2007-11-21 13:40:20

[RockCoach]

 

You obviously do not have any idea what you are talking about. You are comparing a City Golf to a M3 BMW. Rather find out why there are price differences before you start talking k@k about something.

Would you care to enlighten us rather than posting inflammatory content. I see facts in gw's post but not so much in yours.

 

FYI - if you perchance visit Debbin, you will find numerous CitiGolfs which will outrun and outhandle M3's and most other exotica without a problem at 1/20th of the price.

 

Sorry to go offtopic here...

 

[greatwhite]

JB' date=' as I have it, the Roubaix was #1 on the comfort scale because it needed less force than the others to displace a certain distance. They interpreted this as beign the most comfortable, thus having the lowest vertical stiffness.

 

I cant read enough German to figure out exactly what their test configuration was. Possibly clamped the BB & headset, applied a known verical load to the dropout & measured the deflection.

[/quote']

 

Agreed on the deflection.

 

Is your german good enough to get any of the lateral stiffness info (my german is non existant)? I'm really keen to see the bigger picture - those frames that are stiff sideways relative to their soft vertical pliance.

 

Especially the CAAD9 frame - I had a CAAD7 which is nearly identical, but personally found the frame disappointing (that should piss off all the 'dale fan boys). I'd be interested to see how my subjective observations relate to test data.

 

[Christie]

GW, to get all the data, I have to buy the article for 2 euro. I tried, but they won't accept my subscription to their on-line payment service without me phoning them

But I've got another plan! I'm going to ask some fimily/friens in Europe to try & buy it, & email it to me. Will post some data when I get it.