Difference in Aluminum types

[Jennifer Smith]

I got a question on the difference between Aluminum alloy types.

What are the characteristics of Al 7075 and other types of Al?

i.e. I currently have a handlebar made from Al 7075 & it flexes quite a bit. I have nightmares of
coming down a rocky section of trail and having my Al 7075 bars breaking from the metal
fatigue. Are there better alloys of Al that won't flex so much or am I just paranoid because my
understanding of Al is that it doesn't flex to much & is prone to failure.

Does any know of a good website explaining the different types of Al & their properties?

Thanks.'

 

[Slacker]

"Jennifer Smith" <[email protected]> wrote in message
news:6i%[email protected]...
> I got a question on the difference between Aluminum alloy types.
>
> What are the characteristics of Al 7075 and other types of Al?
>
> i.e. I currently have a handlebar made from Al 7075 & it flexes quite a bit. I have nightmares of
> coming down a rocky section of trail and having my Al 7075 bars breaking from the metal
> fatigue. Are there better alloys of Al that won't flex so much or am I just paranoid because
> my understanding of Al is that it doesn't flex to much & is prone to failure.
>
> Does any know of a good website explaining the different types of Al & their properties?
>
> Thanks.'

IMHO that's not going to give you the necessary info you're looking for. Two companies could use the
same material, but one might make a flexy POS with the other making a super stiff one. Plus some
companies are using are using proprietary material for their bars. Don't you just want to know who
makes a good bar??

My riding weight is bout 200 lbs and I'm using an
http://cambriabike.com/bars&ends/answer_protaper_aluminum_riser_bar.htm for both XC & DH. It's a
great bar....strong & stiff. There are others too.

--
Slacker

 

[Jose Rizal]

Jennifer Smith:

> I got a question on the difference between Aluminum alloy types.
>
> What are the characteristics of Al 7075 and other types of Al?

http://www.metalsonline.com/Research/Property/step1.asp

> i.e. I currently have a handlebar made from Al 7075 & it flexes quite a bit. I have nightmares of
> coming down a rocky section of trail and having my Al 7075 bars breaking from the metal
> fatigue. Are there better alloys of Al that won't flex so much or am I just paranoid because
> my understanding of Al is that it doesn't flex to much & is prone to failure.

Essentially, flexing aluminium alloy structures is not ideal since Al's fatigue life is much shorter
than steels and flexing tends to imply a high load. Also loads on Al alloy structures are cumulative
in terms of fatigue life, whereas loads on steel structures have negligible effect on fatigue life
when below a critical value, even when flex is present. Consider that most springs are made of
steel, whereas Al springs are unheard of.

If your handlebar's flexing is making you nervous, get one meant for downhill riding: these tend to
be thicker (and heavier) and might flex a lot less.

> Does any know of a good website explaining the different types of Al & their properties?

See above.

 

[Mark Hickey]

"Jennifer Smith" <[email protected]> wrote:

>I got a question on the difference between Aluminum alloy types.
>
>What are the characteristics of Al 7075 and other types of Al?
>
>i.e. I currently have a handlebar made from Al 7075 & it flexes quite a bit. I have nightmares of
> coming down a rocky section of trail and having my Al 7075 bars breaking from the metal
> fatigue. Are there better alloys of Al that won't flex so much or am I just paranoid because
> my understanding of Al is that it doesn't flex to much & is prone to failure.

In essence, you won't find any aluminum bars built with the same wall thickness that act much
difference. To grossly oversimplify, all the aluminum alloys used in the bike business acts
about the same.

There is a tradeoff between increasing the ultimate shear strength and the ductility (the ability of
the material to stretch without being permanently deformed, more or less). The two goals are
normally at odds with each other - think of it in terms of a fine china plate on one end of the
scale and a frisbee on the other... but with all the "normal alloys" being clumped near the center
of the range.

>Does any know of a good website explaining the different types of Al & their properties?

There are a lot of them out there, but I doubt you'll find one that really digs deep enough to
answer the specific question you're asking. In the end, design, material purity, and quality control
are the things that will keep you out of trouble. The easy answer is to replace your bars every year
with relatively heavy aluminum bars (kind of a brute force insurance policy). Stay away from
ultra-light (aka stupid-lite) bars if you have a flex issue with your current bars.

Mark Hickey Habanero Cycles http://www.habcycles.com Home of the $695 ti frame

 

[John Morgan]

> i.e. I currently have a handlebar made from Al 7075 & it flexes quite a
bit.
> I have nightmares of coming down a rocky section of trail and having my Al 7075 bars breaking from
> the metal fatigue. Are there better alloys of Al that won't flex so much or am I just paranoid
> because my understanding of
Al
> is that it doesn't flex to much & is prone to failure.

Daaaaamn! That's one big woman!

-John Morgan

 

[Stephen Baker]

Mark says:

>the ductility (the ability of the material to stretch without being permanently deformed, more
>or less).

I'm going to bet that the Resident Metallurgist (UK branch) is willing to correct me if I'm wrong,
but that quality is called elasticity, not ductility, IIRC

Steve just don't ask me what "ductility" _is_ though....

 

[Simon]

"Stephen Baker" <[email protected]> wrote in message
news:[email protected]...
| Mark says:
|
| >the ductility (the ability of the material to stretch without being permanently deformed, more
| >or less).
|
| I'm going to bet that the Resident Metallurgist (UK branch) is willing to correct me if I'm wrong,
| but that quality is called elasticity, not
ductility,
| IIRC
|
| Steve just don't ask me what "ductility" _is_ though....

Elastic deformation: nonpermanent deformation, totally recovered upon release of an applied stress.

Ductility: A measure of a material's ability to undergo appreciable plastic deformation before
fracture; it may be expressed as percent elongation or percent area reduction from a tensile test.

In essence you are both correct but within varying parts of the original post. I believe the elastic
deformation is what is happening within the bars and the ductility that Mark H was referring to was
within the process of actually making them.

Simon.....Paid semi attention at university )

 

[Zerohm]

"Simon" <[email protected]> wrote in message
news:2Kl%[email protected]...
>
> "Stephen Baker" <[email protected]> wrote in message
> news:[email protected]...
> | Mark says:
> |
> | >the ductility (the ability of the material to stretch without being permanently deformed, more
> | >or less).
> |
> | I'm going to bet that the Resident Metallurgist (UK branch) is willing
to
> | correct me if I'm wrong, but that quality is called elasticity, not
> ductility,
> | IIRC
<snip>

Have a look at www.principalmetals.com which gives a very good explantion of the differing grades of
aluminium and has an excellent glossary of terms...

Zerohm

 

[Jose Rizal]

Stephen Baker:

> Mark says:
>
> >the ductility (the ability of the material to stretch without being permanently deformed, more
> >or less).
>
> I'm going to bet that the Resident Metallurgist (UK branch) is willing to correct me if I'm wrong,
> but that quality is called elasticity, not ductility, IIRC

Correct. Ductility is the ability to deform permanently. Amongst gold's valuable properties is its
high ductility, easily deformed into any shape.

 

[Andy Chequer]

"Simon" <[email protected]> wrote in message
news:2Kl%[email protected]...
>
> "Stephen Baker" <[email protected]> wrote in message
> news:[email protected]...
> | Mark says:
> |
> | >the ductility (the ability of the material to stretch without being permanently deformed, more
> | >or less).
> |
> | I'm going to bet that the Resident Metallurgist (UK branch) is willing
to
> | correct me if I'm wrong, but that quality is called elasticity, not
> ductility,
> | IIRC
> |
> | Steve just don't ask me what "ductility" _is_ though....
>
> Elastic deformation: nonpermanent deformation, totally recovered upon release of an
> applied stress.
>
> Ductility: A measure of a material's ability to undergo appreciable
plastic
> deformation before fracture; it may be expressed as percent elongation or percent area reduction
> from a tensile test.
>
> In essence you are both correct but within varying parts of the original post. I believe the
> elastic deformation is what is happening within the
bars
> and the ductility that Mark H was referring to was within the process of actually making them.
>
> Simon.....Paid semi attention at university )

Just how many metallurgists are there around here?

Andy Chequer

 

[Shaun Rimmer]

Andy Chequer <bicycle.repair.man@(removethisbittosend)secretworldgovernment.org> wrote in message
news:YzR%[email protected]...
>
> "Simon" <[email protected]> wrote in message
> news:2Kl%[email protected]...
> >
> > "Stephen Baker" <[email protected]> wrote in message
> > news:[email protected]...
> > | Mark says:
> > |
> > | >the ductility (the ability of the material to stretch without being permanently deformed,
> > | >more or less).
> > |
> > | I'm going to bet that the Resident Metallurgist (UK branch) is willing
> to
> > | correct me if I'm wrong, but that quality is called elasticity, not
> > ductility,
> > | IIRC
> > |
> > | Steve just don't ask me what "ductility" _is_ though....
> >
> > Elastic deformation: nonpermanent deformation, totally recovered upon release of an applied
> > stress.
> >
> > Ductility: A measure of a material's ability to undergo appreciable
> plastic
> > deformation before fracture; it may be expressed as percent elongation
or
> > percent area reduction from a tensile test.
> >
> > In essence you are both correct but within varying parts of the original post. I believe the
> > elastic deformation is what is happening within the
> bars
> > and the ductility that Mark H was referring to was within the process of actually making them.
> >
> > Simon.....Paid semi attention at university )
>
> Just how many metallurgists are there around here?

Not enough.

Shaun aRe - There is no such thing as 'too many metalurgists'. It's a fact.

 

[Supabonbon]

"Slacker" <[email protected]> wrote in message
news:<Yh0%[email protected]>...
> "Jennifer Smith" <[email protected]> wrote in message
> news:6i%[email protected]...

> > What are the characteristics of Al 7075 and other types of Al?
> >
> > i.e. I currently have a handlebar made from Al 7075 & it flexes quite a bit. I have nightmares
> > of coming down a rocky section of trail and having my Al 7075 bars breaking from the metal
> > fatigue. Are there better alloys of Al that won't flex so much or am I just paranoid
> > because my understanding of Al is that it doesn't flex to much & is prone to failure.
> >
> > Does any know of a good website explaining the different types of Al & their properties?
> >
> > Thanks.'

>
> My riding weight is bout 200 lbs and I'm using an
> http://cambriabike.com/bars&ends/answer_protaper_aluminum_riser_bar.htm for both XC & DH. It's a
> great bar....strong & stiff. There are others too.

Or you could go steel: http://www.profileracing.com/ /s

 

[Shaun Rimmer]

Andy Chequer <bicycle.repair.man@(removethisbittosend)secretworldgovernment.org> wrote in message
newsKY%[email protected]...
>
> "Stephen Baker" <[email protected]> wrote in message
> news:[email protected]...
> > >Just how many metallurgists are there around here?
> > >
> > >Andy Chequer
> > >
> >
> > <grasshopper> Only you, master! </grasshopper>
> >
> > ;-)
> >
>
> I'm not sure wether that was wierder than aRe's post. I suspect that you
are
> both very strange.

He makes an awkward but willing and ca[able apprentice - He actually brought me a bucket of steam,
but spilt half of it on the way.

Shaun aRe

 

[Michael Johnson]

> Just how many metallurgists are there around here?
>
> Andy Chequer
>
>

Umm, there's me, though I'm more of a chemical metallurgist (blast furnaces/smelting/phase diagrams)
kinda guy. Keep my mouth almost shut on the physical metallurgy side of life. I am sort of a chronic
lurker though.

There's another metallurgist from Los Alamos in the rec.bicycling.* world. Dave K is a very
knowlegable guy.

Anyway -- it's all about design and manufacturing finnese, not materials in these low stress,
undemanding operational environment machines we call bicycles.

Mike Johnson Los Alamos, NM