This is a debate that....

has gone on for many years. Having ridden frames made of each of these materials I've come to to two conclusions. The first is, they all make good frames as long as the manufacturer is doing their part in the design department. And the second being, my butt can't tell the difference between a well exicuted 6061, 7005, or 7075 frame. How long a frame made of any of the above will last is a toss up. All aluminium frames will break eventually. It just depends on how they are ridden. And of course all of this assumes no manufacturing defects and a knowledgeable and inteligent use of the material by the builder.

Bottom line, don't sweat what the tubes are made of, but rather how they are used, and how well made the frame is.

Good Dirt

 

7075 is by far the strongest, but it can't be welded, and there are very minimal differences from a riders standpoint between 6061 and 7005.

 

7075 is by far the strongest, but it can't be welded, and there are very minimal differences from a riders standpoint between 6061 and 7005.

Nope 7075 can be welded, it's just little more tempermental. The major difference is 6000 series needs a more involved heat treating process to reach optimal strength (T6) which is a bit less than 7000 series.

 

Then there is Scandium.....which is just an Al alloy with Sc added into it. I thought this was 7005 for a while but it Easton have GX2 and call it 7000.

....but the notion is these different Al alloys have different strengths....so you can make your tubes thinner....and lighter....or thicker and are more able to take repeated flexing.

 

Isn't it also true (claimed) that 6061 aluminium has better metal fatigue properties than the 7 series versions?

V.

 

It is true. 6061 flexes while 7075 will snap. Because 7075 IS a bit stronger they make it thinner... ah! That's important to consider. It's like this; It's all about the rider's weight and the purpose of the bike. It your heavy and you want to do bike stuff: 6061 I'm 235lbs and have snapped a 7075 and it hurt LoL I do the same stuff on my cheaper 6061... no problems. Spend your money on your wheels

 

My understanding: It really depends if the frame is re-treated after welding. When you weld 6061, you lose about 80% of the strength around the weld. Re-treating it can bring it back to T4 and T6 strengths, but how many frame manufacturers do you think go to that added step properly? It's kinda like saying "carbon is stronger than steel" - yeah, if you do it properly in like 13 stages like someone like Boeing or Toyota is going to - but if you're, oh I dunno, Fuji, Scott or Giant, do you really actually believe they spend that much time/money on every frame? Absolutely not.

The tensile strength of 7075 against 6061 is massively higher, but it's also softer. However, with 7075 you get more steength, but a bigger hit is more likely to just snap it in half (if you're familiar with chill-casting vs slow/air casting, it's a bit like that) - that is to say 7075 will handle small hits better, and spring back to it's original shape, but the higher stength you make it the worse it's going to fail (hence why you see some frames just completely combust when they take big hits). 7075 is much like 6013 in the ride quality - I currently ride a 6061 singlespeed and a 6013 geared XC race bike - as soon as I get a steel frame, the 6013 is going in the bin.

So in conclusion, if you want your bike to behave like a wet noodle, go for 7075.

If you don't want the fatigue properties of Aluminium, go for Ti. Sc will give you a nicer ride (and will be lighter than Ti), but it'll be a disposable frame.

It'd be nice if Thylacine weighed in on this one, actually (hopefully correct anything I've got wrong).

Edit: FWIW, 6013 is Aluminium, Magnesium, Silicon and Copper - it should be very quickly obvious why it behaves the way it does... on the other hand it's virtually immune to stress corrosion.

 

Nope 7075 can be welded, it's just little more tempermental.

You're confusing 7075 with 7005. It's commonly known that 7075 is considered non-weldable for structural applications.

http://www.lincolnelectric.com/knowledge/articles/content/comistakes.asp

 

Nope 7075 can be welded, it's just little more tempermental. The major difference is 6000 series needs a more involved heat treating process to reach optimal strength (T6) which is a bit less than 7000 series.

7075 itself cannot be welded economically or reliably by any method used by bicycle companies due to the high zinc content of the alloy. The only way to make it weldable is to add scandium to the alloy mixture (which is what the Easton SC7000 tubing essentially does). There are NUMEROUS 7xxx series alloys and not all of them are weldable. 7005 is as is 7120 and both are used to make bike frames from. 7075 and 7129 for example have historically ONLY been used to make bonded frames from (trek and Mitaya in the late 80s/early 90s).

 

My understanding: It really depends if the frame is re-treated after welding. When you weld 6061, you lose about 80% of the strength around the weld. Re-treating it can bring it back to T4 and T6 strengths, but how many frame manufacturers do you think go to that added step properly? It's kinda like saying "carbon is stronger than steel" - yeah, if you do it properly in like 13 stages like someone like Boeing or Toyota is going to - but if you're, oh I dunno, Fuji, Scott or Giant, do you really actually believe they spend that much time/money on every frame? Absolutely not.

Your understanding was correct up until your second period. After that you got it wrong. Every bike manufacturing facility working with 6061 to make frames does indeed bring the frames back to a T6 temper after welding thru usage of these massive ovens which can heat-treat whole racks of frames at once.

The tensile strength of 7075 against 6061 is massively higher, but it's also softer.

I think you need to learn some terms better. While in some cases very hard materials do become brittle (such as GLASS) in the terms of most structural metals this isn't really the case. Only way most metals suddenlly shatter is if there was a flaw in the metal to begin with (like an air bubble in a cast turbine blade of a jet engine). But just because a high strength alloy might only stretch 7 or 8% before failure doesn't mean its going to do it in a bicycle frame. Most people don't realize how far 7% is when its over a tube that's a couple feet long (like the downtube is).

7075 is much like 6013 in the ride quality - I currently ride a 6061 singlespeed and a 6013 geared XC race bike - as soon as I get a steel frame, the 6013 is going in the bin.

So in conclusion, if you want your bike to behave like a wet noodle, go for 7075.

Again you know squat about the alloys in question or how little they really relate to the ride quality of the frame. All the aluminium alloys used in bicycle frames are within a ONE PERCENT range of one another when it comes to stiffness. The only way a 7075 frame is going to be a noodly ride is if you use smaller diameter tubing than the one that used say 6013 or 6061. A LOT smaller... like steel frame size tubing.

Edit: FWIW, 6013 is Aluminium, Magnesium, Silicon and Copper - it should be very quickly obvious why it behaves the way it does... on the other hand it's virtually immune to stress corrosion.

Ok, quickly explain why it does then. Try not to make yourself look like an even bigger idiot than you already have though when you do it.

 

Yes dude metallurgy 101 you need to take. As stated above the alloys are 1-2 percent additions of other elements and it is not at all obvious why they behave the way they do (curious indeed how you know what silicon and the like do for a alloy). You build the alloy and then you test it as has been done for decades.

And it is indeed true that Al alloys are first annealed to enable them to be worked/welded and then at the end the whole frame is tempered back. Clearly this is so you can put a warranty on a frame. And yes you are paying for it and they do it (its a fact). Takes some hours but is mass production.

also for the record Sc (scandium) is an Aluminium alloy...just like 6061 but it is marketed really well at the moment, and all the punters are falling for it as a "new" material. It aint, it just Aluminium.

 

Scandium IS an element, but the marketing people have taken to calling aluminium with scandium added to the alloy mix "scandium tubing" instead of the more accurate "scandium-aluminium alloy tubing". This is especially amusing sine aluminium-lithium (Al-Li is the common abbrev) alloy tubing is never called "lithium tubing".

http://en.wikipedia.org/wiki/Scandium

 

Well, alloying is not alchemy. There is definitively some expectation of the alloy properties depending on what you are alloying. Of course, once you have cooked it up, what ends up may be different. I believe many modern alloys are primarily serendipitous discoveries, fine tuned by some foresight and trial and error.

Oh and Sc is a metal (I know you know, but just making sure) not an alloy by itself. Its added to aluminium to make a "Scandium" alloy material. Was isolated in 1879 and used by Russians to make submarine launched ICBMs (love Wikipedia )


V.

 

Yeh the Sc comment came out a bit wrong didn't it. :skep:
..was shooting at

If you don't want the fatigue properties of Aluminium, go for Ti. Sc will give you a nicer ride (and will be lighter than Ti), but it'll be a disposable frame.

Its just there are many that think the Sc alloy is that and that alone, when its just some marketing spin. Drives me crazy.

Check out Be alloys one day, really quite appealing but toxic.

 

Be alloys are also ridiculously expensive, and thus not very practical for bicycle usage.

 

I'd like to see a bike made from liquidmetal...I said that when I was into lacrosse too, and my dream came true the year after I stopped playing and has been very successful (dangit...)

 

Scandium IS an element, but the marketing people have taken to calling aluminium with scandium added to the alloy mix "scandium tubing" instead of the more accurate "scandium-aluminium alloy tubing". This is especially amusing sine aluminium-lithium (Al-Li is the common abbrev) alloy tubing is never called "lithium tubing".

Why get your panties in a knot? 953 is carpenter C455, and Columbus XCR is Gilco APX4.

What, you think 'Prestige' is actually prestigious? :skep:

I give anything the thumbs up if it helps people differentiate. Scandium actually does inhibit grain growth in the HAZ making the frames much stronger in that critical area, so it probably deserves an honourable mention because it is significantly different than it's parent 7005.

So, which is better, 7005 or 6061?

In the real world, it doesn't make a scrap of difference.

As mentioned earlier, you can't make a complete bike from 7075 because it's non-weldable, so you can count it out. However, for plate components it's lightyears better than either 7005 or 6061.

 

I'm sure everyone here knows that you don't make things out of pure Sc, Ti, or many other materials. Hell, if you're going to attack someones argument on that basis, geez... you may have just overlooked little basic.

Only way most metals suddenlly shatter is if there was a flaw in the metal to begin with (like an air bubble in a cast turbine blade of a jet engine). But just because a high strength alloy might only stretch 7 or 8% before failure doesn't mean its going to do it in a bicycle frame. Most people don't realize how far 7% is when its over a tube that's a couple feet long (like the downtube is).

Depends what you call a 'flaw'. What is considered to be a flaw for some purposes may actually be a desired property. It sure as hell isn't the *only* way though.
The point I was making here though is how much the frame will flex. If you allow it to take that tension, you'll end up with a frame that feels like it's flopping all over the place. It probably won't snap though. On the other hand with less tolerance to it, it'll create a stiffer ride - but at some point the allow is going to separate from itself (ie, snap in half). It's pretty obvious you've tried to distort what I've pointed out though and have ignored everything correct.

Ok, quickly explain why it does then. Try not to make yourself look like an even bigger idiot than you already have though when you do it.

Bigger idiot? Oh my. Sorry, but I don't really have time for a detailed chemistry lesson, an explanation of the chart of the elements, and a simple explanation on chemical bonds (but here's a hint: look at the EPS). At least here I admitted I may be a bit off - much of what you've said isn't any closer though and under different circumstances would make you look just as silly. Others are right that I'm not a metallurgist, though lets just say a reasonable chem background.

As stated above the alloys are 1-2 percent additions of other elements and it is not at all obvious why they behave the way they do (curious indeed how you know what silicon and the like do for a alloy). You build the alloy and then you test it as has been done for decades.

One might wonder if it makes so little difference with such a small percentage change in materials, why we bother to have these different alloys.
People aren't just adding random elements to alloys with no idea what would happen. You can get a reasonable understanding on paper to get ideas on how to make an alloy better (you make it sound like they've just gone "Two bats wings, an eye of newt, Heart of an Ox..." and hoped for Diamond).

You all seem to have missed the point here though - I've tried to answer what he's asked based on my own experience of using various frames built on different alloys. And you've done... what exactly to help answer this question?

 

When I was over in the States, probably around 15 years ago I saw an advert for a frame made from 'Boron,' supposedly a declassified aerospace!!!
Anyway, just wondered if anyone had heard of it. I also thought it would give you guys someone else to character assassinate.

Cheers,


James.

 

Hello James

...well where do we start. Papalazauou....sounds like we could start there

Not too familiar with B alloys but chemically the same group as Al so they should exist.
Properties?

 

The boron alloy in question was called Boralyn, and it was actually an aluminium MMC with boron carbide as the ceramic element added. Univega used it for a few years but it went away just as the MMC specialized used for the M2 frames.

 

The boron alloy in question was called Boralyn, and it was actually an aluminium MMC with boron carbide as the ceramic element added. Univega used it for a few years but it went away just as the MMC specialized used for the M2 frames.

That sounds familiar now. I think they marketed the product as boron ceramic, sounded pretty good at the time!

Whilst sort of on topic, what were the early Kline Adroits hade from? A friend of mine had one and it lasted forever before he ripped a hole in the downtube with a rock. At the time I couldn't believe how thin the tubes were, they didn't seem much thicker than Coke cans. He still commutes on it but you wouldn't want to ride it off-road again.
I remember he took it apart after moab one year and the integrated stem and bars were covered in cracks!

Cheers,

James.

 

6061-t6 even though they called it "gradient aluminium" it was just plain old 6061-T6. The only aluminium alloys thus far used for bicycle frames in the past 20 years have been....

6061 (second most popular), 7005 (most popular), 2024 (used by only two brands really, mammoth and liyang), 6013 (aka Alcoa CU-92, used by many brands including Giant and the third most popular), 6066 and 6069 (only major user has been Santa Cruz), 7075 (Trek for their E9 Program bonded frames), 7020 (popular alloy in europe, BMC is a good example of a user), and 7129 (used by Trek in late E9 bonded frames, replaced the use of 7075).

 

Man, this is good stuff, even

if I don't understand half of it, or if it completely sidesteps the questions of what material makes a great aluminum frame. Steel-o-philes get to yack endlessly about 853 or Super-X or whatever... Titus and Santa Cruz and I believe Ventana use 6069, but I've never seen a tubing sticker saying who makes the stuff.

For all the carbon craze that's going on, I still prefer aluminum for mountain bike frames. The same pretty much goes for my road bikes, though I can say I've been trusting carbon forks for almost a decade.

Kind of hoping that after some hyperlight, $$$$ carbon frames fail there will be a shift back to more reasonably priced, yet still light and stiff aluminum frames. And that advancements in aluminum tubing, treating and frame construction continue.

 

Whoa, reply to 11 year old post, could be a new record!

Fun to read my post from 11 years ago. I've got 4 bikes now, all carbon, all carbon handlebars. No failures, catastrophic or otherwise... yet

 

Wow a 10 year old thread resurrection!

Klatu, blah blah,..... necro'd