Merckxrider

[QUOTE]Originally posted by ChipRGW
[B]Unless, when it fails, it does so catastrophically. In which case you have an excuse to get titanium. (implants that is)

FYI: I'm not too concerned about a frame built by the Cannibal. And if you can show me one article regarding a catastrophic frame failure on an aluminum ROAD bike, I'm all ears. I ride steel too BTW and I like both materials. Each has its advantages as others have already stated.

Steve

ParamountScapin 

As stated by folks like Lennard Zinn, 'Bicycling' magazine, RoadBikeRider, etc., aluminum fatigues and they recommend that these frames have a definite lifetime. The recommended life of aluminum frames is suggested to be 4-6 years, depending on mileage, type of riding, etc. Steel frames have no such limit.

The previous analogy between aluminum in beer cans and bike tubing materials is incomplete. The alloys used in each application are so different that the comparison made is meaningless. The aluminum tubes used in bicycle manufacturing are alloyed to be light, stiff, strong and workable (that is, you can build a bike frame at a low cost). The ones in beer cans are alloyed to be easily formed into cans, recycled and even less expensive. A much different requirement. The same can be said for steel. Cans and bicycle tubing are very different. Check out the Columbus, True Temper and Serotta websites for additional information.

TimB

If you want a bike that will last a long time then get either Titanium or steel.

If you like to replace frames every 2-5yrs then get Aluminium or Carbon.

Steel and Titanium are my favourite becasue I don;t like to replace a frame too often. I have other sports which also require equipment changes every few yrs.

shokhead

How often and how many times have you replaced a road frame and for what reason?

TimB

I've owned 4 road frames in the 15yrs I'vebeen riding.
A Peugeot from 88to 90 which was crashed and bent.
Then a Bridgestone RB-1 which was crashed and bent in 94
Then a Bianchi Reparto Course SL which I still have
I bought a Dave Quinn 6060-T6 al bike last year which i hate and am inprocessof converting to TTbike, and themost recent aquisiton which I simply LOVE, A litespeed tuscany which I intend to keep for a very long time indeed!!

Ajay213

Colnago steel bike warranty - What is it 1yr?
Trek Carbon warranty - lifetime
(Above example doesn't really mean anything)

There is so much mis-information out there about materials and lifetimes, strengths/weakness's, etc. Needless to say that a well built carbon or Al frame will last a lifetime providing that you don't run over it with a car or something equally extreme. Granted in an overall sense steel is probably the best over-all material, it's cheap, relatively light, it's more resistant to impact than carbon, is more forgiving to twisting/bending than Al, etc.

Andrew

TimB

and can be repaired if yo don't bend toomany tubes in a crash........
carbon you throw away

Ajay213

To a point. Although depending on WAY to many variables but I bet most of the time if you impacted something hard enough to crack a carbon tube (assuming on a well built frame) it will have distorted the steel tube to the point it couldn't be repaired.

I'd have to go searching again to find out all hard and fast numbers, but if I remember correctly the "breaking point" of a properly laid up carbon fiber tube is in the tens of thousands of psi, that much pressure on a steel tube will pretzlize it real quick, ditto for Al and Ti. You can get an idea of that by reading some of the information from one of the handle-bar makers, they posted test results of pressure/drop testing on their carbon bars vs their Al bars, the CF did A LOT better in terms of strength. Of course the big problem is what happens when it does fail, carbon breaks, it doesn't bend.

And this is all just techno babble crap because it depends on a company properly laying up the frame in composites, which is a lot harder to do than it may seem. Building molds, big ovens, etc it's very expensive to setup. Where as building a steel bike can be a bit easier at the actual construction level, all you have to know is how to weld steel together that you bought from one of the major steel tubing companies (Reynolds for example).

Andrew

ImprezaDrvr

While each material has certain properties that are somewhat inherent to them, it totally depends on how they're alloyed and how they're assembled into a bike.

But the beer can example isn't accurate. Much of what was said there seems to be backwards from conventional wisdom about common alloys of each metal used in manufacturing.

MichaelW

Carbon is pretty soft and can scratch and score easily. Over a lifetime, you are probably going to let is drop against a wall or catch on something sharp.
Dor people ride carbon forks if they have a serious scratch? Just wondering how paranoid riders are.

TimB

what bugs me about carbon bikes is tha people related it to avaition industry and F1 type applications and therefore claim it too be stronger than steel and Titanium.
However a bicycle frame is essentially a tubular structure with lugs carrying the load. The bond area of the tube lug (whether they be carbon, aluminum or titanium) is the determining fatcor ofn the strength of the structure. How well were those components glued together?? You don't realy know.

Aerospce industy construction methods are not transferable to bike frame. Inmy view the best carbon frame is one that is monomoulded not one joined together by lugs.
In a monomoulded structure the stress is distributed throughout the structure, as in aircraft wings or an F1 car's chassis.
in bike frma al the forces have to controlled so that they put the glue joints in shear. Any other force will break the glue joint very easily.

Carbon frame manufacturers can talk about stresses and strains ad nausium, but until they actaully admit that a 1mm thick by 10mm wide ring of Araldite is what holds your head tube tot he down tube I'm not interested intheir marketing.

A carbon frame is only as strong as the glue joint holding it together. Titanium and steel can recover all it's strength at the weld zone making in effect a mono tube structure and therefore stronger than any carbon frame.

Mono mould it and I''l be a happy man.

ImprezaDrvr

Tim, look at Kestrel. IIRC, they're monocoque. I could be remembering wrong, though. And, you're right, but the same principle holds true for most metal frames, doesn't it? IN other words, the frame is only as strong as its weakest weld, no? That's not to say that current welding technology is not such that the welds are incredibly strong and the tubes around the welds are the same, but I have always thought that the heat stress at a weld made that juncture the weakest spot on the frame. Hence, the trend for gusseting the head tubes on mountain bikes that started a few years ago.

Ajay213

There are some metals that will get stronger at the weld point than the metal around it, which would then make it the strongest point on the frame.

And Tim has a point about how a carbon frame is made, gluing the joints together will create a weak point in some ways (shear being the weak side and the most important part of it). Now if anybody does do mono contruction than that goes right out the window and will achieve an incredible amount of strength.

But in the real world I'd put a properly/well constructed carbon frame right up to a steel one in terms of reliability. Now on the real long term side, like 20-40+ years, that may be a bit different, as long as the frame is never "impacted" it will be as strong as the day it was yanked out of the mold, but we all know that bikes take a beating over the course of the years.

Andrew

ImprezaDrvr

I'm honestly curious: Which metals used in bike frames get stronger at the weld? Does it have more to do with the way they're alloyed?

Ajay213

Reynolds 853 is the one that is commonly advertised. And I guess I was a little unclear, the tubing itself get's stronger from the welding, the strength of the joint obviously all depends on the quality of the weld.

Andrew

ImprezaDrvr

Hence the incredible buzz about 853, huh?

Nonetheless, I see a parallel between the bonding used at lugs on carbon tubed bikes and the welding on metal frames. Those are the places most likely to see failure, regardless of material.

Anyone know if Kestrel still makes monocoque frames? Is there anyone else that does the same thing (with carbon)?

Ajay213

One would think that would be a common place for failures, but I wonder if anybody has any real hard data on it to confirm it or not. I'd be interested to see if that is really a weak spot or if it's not really an issue.

853 has a bunch of nice properties, that being one of them, the other is that it has a strength to weight ratio pretty close to Ti (and I mean REALLY close), so basically a good 853 frame and a good Ti frame will weight pretty close to the same assuming they are built to the same strength spec.

Andrew

ImprezaDrvr

I can't cite hard data, just a couple of years working in a shop. This was five or so years ago, though. At any rate, every failure that we saw, road or mountain bike, was at or near a weld. Either head tube or bottom bracket area, or where the dropouts had been welded on to a less expensive frame. Not difinitive at all, just my observation.

shokhead

So can you tell the ride is different beytween 853,631 and 535 or whatever those other numbers are.How do they effect the ride?

ParamountScapin 

Just dropped off my new Scapin EOS3 at my LBS so he could assemble (Campy Record 10-speed gruppo and Ksyrium wheels). Is a TIG welded Columbus Nivacron steel frame and weighed in at 3.14 pounds (54cm) on the LBS digital scale. Think that compares quite well with other materials.

If you wish to do a little historical digging on Lennard Zinn's website you will see some comments/responses from the various carbon fork manufacturers (Look, Reynolds, Columbus, etc.) concerning testing and lifetimes for carbon forks. Essentially, they have none and their failure mode is very nice. By that, I mean it is like steel. It doesn't fail in a castostrophic manner, but 'slowly', giving one time to escape. Some of the comments by these manufacturers included the fact that their cycle testing is beyond 200,000 cycles. Steel was second and failed after about 50,000 cycles, followed relatively closely by titanium. None of them tested aluminum forks, for obvious reasons. Do you see any aluminum forks out there? But all stated that their carbon forks were far superior to any others in both fatigue testing and strength testing. They also stated that, with the exception of a couple of "Pro Only" racing forks, there was no weight limit for the use of their forks.

Also, Ajay213 is mistaken about aluminum. These frames have a limited lifetime. And, as stated before, it is recommended that one adhere to a 4-6 year useful life for aluminum frames. Titanium, graphite and steel frames do not have this lifetime problem. You can hurt them if you crash or damage, but under normal riding conditions you will not wear them out.

Ajay213

Who says there is a lifetime on Al frames? And if that is so why does one of the largest Al bicycle companies (Cannondale) give out lifetime frame warranties on all frames except downhill models? Ditto for Trek and I would imagine a number of others.

Andrew

ImprezaDrvr

There was a time in recent history when Cannondale had a 5 year warranty on their frames. THey did when I sold them in the late nineties, on their high end roadie bikes.

TimB

You'e rightthat theres a paralle between bonded carbon bikes aka OCLV, Time, et al and metal frames. The point is that the material carryingthe load has a greater yield strength in metal than in epoxy resin. S if we agree that a frame is only as strong as the joint holding it together than the metal frame will always be stronger than the bonded one
Epoxy resings and glues are only strong in shear not under impact loading, tensile or compressive loads either.

As for metals which show full recovery, youhave to look more at the heat treating processes than the metal itself. Different metals require different heat treatment to show strength recovery.
Titanium alloys 3Al/2.5V and 6Al/4V are actually stronger in the weld zone due to there being uncontaminated material there.
Heta treated AL frames like 6061-T6, 7020-T6 also show up to 95% strength recovery int he weld zone which still has a higher yield than a epoxy joint.

You onlyget the full advantage of carbon fibre composites when the frame is Mono Moulded, and I believe Kestrel is the only compnay still doing them.

As for frame life times; that may be a non issue but it all depends on how a frame is used and the strenght of the rider.
I know guys who go through 2 Easton Ultralite frames a year and train on steel which they'vehad for yrs. They also would not touch a carbon frame unless it was given to them free of charge.
we must be very care ful when comparing frmae materials. Marketers want us to believe that we are ridingthe same equipment as the Pro's. for those that can afford it, fine go for carbon. I 'm n=more discerning about my investment. If the frame does'nt give 10yrs life then it'sa no go. If I need a lightweight race bike I can get a cheap AL frame made locally, but the bike I spend themost time on is always goingt o be steel or titanium.

Al and Carbon have their uses, but they are limited in their life. It's written in the fatigue life of the material. We can't change physics.

Merckxrider

hmmm... so much invaluable information on this forum. I'd love to know everyone's sources. As I've already suggested, if I need a new frame in five years or so, then that's fine with me. That's twice the amount of time I'll get compared to the computer I'm typing on right now! I have a few more questions for ya'll, though. Firstly, I've looked at a LOT of frames recently. Is it just me or is aluminium saturating the market? And if it's a weaker, limited durability type of material, which could unexpectedly explode at any moment, then why would bigtime frame manufacturers be pushing this material the most? Do they wish for us to become injured? Or do they use aluminium knowing it'll wear out quickly, forcing the consumer to buy a new bike, thus raising their profits (conspiracy theory). Okay, so I'm joking around somewhat, but, I am interested in hearing opinions. It seems to me, if steel is the ultimate, comfy, cost-effective/ strongest material that "it" would be dominating the market, right? Lastly, in the April issue of Pro Cycling there's a freebie info. pack on frame manufacturers which is just fascinating. It's worth a look.

Steve

Ajay213

You have to realize that most people on this board are not "average" cyclists, we are more in the enthusiast and above category. Remember that the average buyer probably buys a bike and rides it maybe 100 miles a year. We see it all the time when somebody is asking about some great used bike he found, such a person will have found a 4-5yr old bike that is in like new condition, and that's because it is. People will buy a bike for all kinds of reasons, maybe they saw Lance on the cover of SI and remembers when he was younger and loved to ride, so he'll go out buy a nice bike and never ride it, or maybe he wants to ride with his kids, etc. There are a million reasons.

So maybe these companies do turn out an inferior product knowing that the majority of people will never wear out a frame. Seems like a risky decision to me for a whole product line, but it's possible. On the other hand I'm sure there is some of that as well, as mentioned by another poster, he knows people that wear out frames quickly, they are probably very lightweight racing level frames that aren't built as sturdy as a "normal" frame.

The Scattante that is sold by Supergo claims to have a mono built main triangle, and that's a budget brand. Trek actually builds carbon lugs so they can pay more attention to the "direction" of the carbon weave (like most composites like it, there is more strength in certain directions). I don't know about the rest.

Obviously we can't change physics, but we can engineer something to the point that the fatigue life doesn't come into play. As a good example look at any airplane, they are built primarily of Al but have lifespans of 20+ years, because they are "overbuilt" to do that. And past their "lifetime" they are pulled out of service and most of the time go into the private sector.

Granted that's not a great example because the amount of engineering that goes into an airplane is lightyears ahead of what goes into a bike, but shows that it is possible to build past those limits. But I have no idea if any bike manufacture does that or not.

Andrew