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Old 07-29-11, 05:44 AM   #1
wroomwroomoops
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6061 aluminum is NOT like 7075 aluminum. They're not even ALMOST similar!

Dear you who are reading, please spread the word: aluminum 6061 is much softer than 7075. 6061 is much easier to machine with CNC, because of its softness, but the chainrings made from aluminum 6061 alloy last orders of magnitude less, than those made from 7075 aluminum, due to the significant difference in hardness.

I am posting this, and hoping you will spread the word, because I'm up to here with dishonest sellers who take my money for a 7075 chainring and send me a replacement which is made of 6061, even though I clearly stated that I do NOT WANT a chainring made of aluminum 6061.

This particualr seller ran out the clock on me, so I could not start a complaint through the PayPal resolution center (45 days max after the transaction), but I still sent an e-mail to PayPal.

Sellers thrive on general ignorance. Heck, the in-built obsolescence of chainrings made of aluminum 6061 is a GOOD THING from their point of view, as you will be forced to buy a new chainring much faster than if it were made of aluminum 7075 or better yet, steel.


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Old 07-29-11, 05:57 AM   #2
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An what does this have to do with mechanic of a bike; did you buy it from this forum?

If you have an issue with a seller, and use paypal, you have 45 days, your fault for not resolving the issue before that, you obviously knew the product sent was wrong when you recived it, you should have sorted the issue before the 45 day limit was up.
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Old 07-29-11, 06:27 AM   #3
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sounds like someone did not do ay research.
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Old 07-29-11, 08:10 AM   #4
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An what does this have to do with mechanic of a bike;
People who visit this subforum are most likely interested in facts related to bicycle mechanics; most of them want to learn new things that pertain to bicycle mechanics, and some may not yet know that not all aluminum chainrings are created equal.
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Old 07-29-11, 08:19 AM   #5
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Originally Posted by wroomwroomoops View Post
People who visit this subforum are most likely interested in facts related to bicycle mechanics; most of them want to learn new things that pertain to bicycle mechanics, and some may not yet know that not all aluminum chainrings are created equal.
I think that fairly well known and most us us know enough to stay with reliable suppliers like Shimano, Campy, Suguino and some others. I know you are in Europe so did you buy from a European supplier or from the US?
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Old 07-29-11, 08:19 AM   #6
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Seems informative to me, for people that don't realize the aluminum you get does matter. He should have probably put the ebay anecdote elsewhere. He did say the seller ran the clock out on him, so the comments made to him by jimc101 are unjustified IMO.
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Old 07-29-11, 08:21 AM   #7
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Jimc

I guess I think this is a valuable post on this board. Did you or many others know this.
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Old 07-29-11, 08:24 AM   #8
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I personally found the post informative.
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Old 07-29-11, 08:28 AM   #9
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Why unjustified, the OP was having a rant about nothing related to bike mechanics, but to a bad buying experiance elsewhere, if it has been relevant to fixing a bike, fair enough, but if didn't.

For different types of Aluminium, there is far more to 6061(t6) than being softer that 7075, they have different properties, and are better suited to different applications google search it.
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Old 07-29-11, 08:38 AM   #10
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Wow. Thanks for the info on the differences. If I ever knew it I forgot it.
Replacing parts= bike mechanics to me...
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Old 07-29-11, 08:40 AM   #11
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Maybe I'm naive but I thought it was well known that there are a wide variety of aluminum alloys just as there are steel and Ti alloys. Steel used in bikes varies from "Hi-Ten" (low cost, low strength plain carbon steel) through several grades of Chrome-Moly up to the exotic high strength alloys like Reynolds 853. Titanium alloys vary in strength and durability from CP (commercially pure) grade up through 6/4 Al/V.

Aluminum alloys are also available in a wide variety of grades varying in strength, hardness, wear resistance and cost.
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Old 07-29-11, 08:43 AM   #12
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Thanks for the info, sorry to hear you got burned.


To all of those who thinks the OP was a waste:

Don't read it. Save your electrons for what you are interested in.
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Old 07-29-11, 09:55 AM   #13
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Not everybody knows the same things that you know, I thought the post was informative, thanks.
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Old 07-29-11, 10:10 AM   #14
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Quote:
Originally Posted by jimc101 View Post
Why unjustified, the OP was having a rant about nothing related to bike mechanics, but to a bad buying experiance elsewhere, if it has been relevant to fixing a bike, fair enough, but if didn't.

For different types of Aluminium, there is far more to 6061(t6) than being softer that 7075, they have different properties, and are better suited to different applications google search it.
So product and material selection related to maintenance and part replacement has no bearing on mechanics, you say? I THINK NOT!

Thanks for the info, wroomwroomoops.
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Old 07-29-11, 11:45 AM   #15
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Quote:
Originally Posted by wroomwroomoops View Post
I am posting this, and hoping you will spread the word, because I'm up to here with dishonest sellers who take my money for a 7075 chainring and send me a replacement which is made of 6061, even though I clearly stated that I do NOT WANT a chainring made of aluminum 6061.

This particualr seller ran out the clock on me, so I could not start a complaint through the PayPal resolution center (45 days max after the transaction), but I still sent an e-mail to PayPal.
Have you tried negotiating with the seller, in spite of the resolution period expiring? A seller might be clueless like the rest of the public, not appreciating the significance of the difference in alloys.

In the past I bought a webcam from a seller who was a front for another seller and just copied info from some leaflet, never trying out the specifications. As the camera did not meet the specs, the seller refunded me and I even kept the camera. Conversely, I once refunded a buyer 6 months after his purchase, after it became that the problem was with the product and not any misuse.
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Old 07-29-11, 11:55 AM   #16
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at times, I've wondered why some parts were made from 60xx while others were made from 70xx aluminum, but now I think I understand better.
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Old 07-29-11, 12:06 PM   #17
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The OP's post begs a forum titled:

"cat 'post' > /dev/null"

=8-)

...and of course the OP is another in the long line of posters who can't seem to bothered to use the Bike Forums forum for vendor reviews...which is where the original post belongs.
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Old 07-29-11, 12:14 PM   #18
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Originally Posted by trek330 View Post
I personally found the post informative.
Not really because it left out a real important part.

Most parts are made of 6061-T6 aluminum. The T6 is a heat treatment that significantly affects the properties of the metal.
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Old 07-29-11, 12:15 PM   #19
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Quote:
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The OP's post begs a forum titled:

"cat 'post' > /dev/null"

=8-)

...and of course the OP is another in the long line of posters who can't seem to bothered to use the Bike Forums forum for vendor reviews...which is where the original post belongs.
I didn't make a vendor review, I made a short and hopefully clear explanation on the difference between two aluminum alloys often used for bicycle chainrings. I stated that aluminum 6061 is much easier to machine, but the chainrings made from it last much less. For the maker this is an advantage: the softer Al 6061 will take less time to machine (and will require fewer CNC bit replacements) than the harder Al 7075. Also, the hapless user will be forced to replace the chainring much, much sooner than if the chainring were made from Al 7075, possibly leading to another sale. That is why I said that these people thrive on ignorance, and I would like to, at least a little bit, decrease that ignorance.

Furthermore, if you don't like this thread, just don't read it, let alone post in it.
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Old 07-29-11, 12:39 PM   #20
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OP, thanks for the info. I think a post that is about the durability of different and popular aluminum alloys definitely is of interest to me as a reader of the Bicycle Mechanics forum.
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Old 07-29-11, 12:59 PM   #21
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Not really because it left out a real important part.

Most parts are made of 6061-T6 aluminum. The T6 is a heat treatment that significantly affects the properties of the metal.
Good one Retro Grouch!


=8-)
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2. I like anyone will comment in other areas.
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4. I will provide information as I always have to others that I believe will help them protect themselves from unscrupulous mechanics.
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Kahane, Howard. Logic and Contemporary Rhetoric: The Use of Reason in Everyday Life
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Old 07-29-11, 01:04 PM   #22
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"I am posting this, and hoping you will spread the word, because I'm up to here with dishonest sellers who take my money for a 7075 chainring and send me a replacement which is made of 6061, even though I clearly stated that I do NOT WANT a chainring made of aluminum 6061.

This particualr seller ran out the clock on me, so I could not start a complaint through the PayPal resolution center (45 days max after the transaction), but I still sent an e-mail to PayPal.

Sellers thrive on general ignorance. Heck, the in-built obsolescence of chainrings made of aluminum 6061 is a GOOD THING from their point of view, as you will be forced to buy a new chainring much faster than if it were made of aluminum 7075 or better yet, steel."


Word and Phrase Count:

sellers = 2
seller = 1
PayPal = 2
thrive on ignorance = 1
complaint resolution center = 1
dishonest = 1
money = 1
buy = 1
NOT WANT = 1

...sounds like a vendor complaint to me.

=8-)
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2. I like anyone will comment in other areas.
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4. I will provide information as I always have to others that I believe will help them protect themselves from unscrupulous mechanics.
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Kahane, Howard. Logic and Contemporary Rhetoric: The Use of Reason in Everyday Life
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Old 07-29-11, 01:18 PM   #23
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Not really because it left out a real important part.

Most parts are made of 6061-T6 aluminum. The T6 is a heat treatment that significantly affects the properties of the metal.
It is true that aluminum alloy components are also characterized by their temper designation, but the fact is that practically all aluminum chainrings, chainring bolts and cranksets have T6 temper, be it 6061-T6 or 7075-T6. A 6061 alloy component, in any case, cannot be hardened to the level a 7075 component can. In other words, a bicycle component made of aluminum 6061 cannot reach the hardness it would have if it were made of aluminum 7075, regardless of the tempering the 6061 component is subjected to.

I didn't mention this in my opening post because the tempering doesn't change the fact that a 6061 alloy component will in all circumstances be softer than if it were made of 7075 alloy, and because I wanted to keep my post simple. I also didn't aim at perfection, because I would never finish writing the post and starting this thread, if I aimed at divine perfection.
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Old 07-29-11, 01:32 PM   #24
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What is the big deal about this post? It's of or related to bicycle mechanics, and if people are that offended, simply don't post.

6061 is about 30% softer than 7075, assuming a T651 temper, which is very common. However they've both very easy to machine, though 7075 has a tendency to flex a tiny bit, so depending on your surface finish requirements, may require a lighter finish pass. 7075 doesn't have the same corrosion resistance as compared to 6061 though. Hard anodizing parts takes care of the difference in wear characteristics between the two allows though
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Old 07-29-11, 01:36 PM   #25
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some parts get cut in a whole, die cut, so that process favors the softer alloy
cost savings, in lower price points.
and in other thicker parts like crank arms is fine.

7075t6, Ergal in some descriptions, is better suited to cutting teeth individually..
CNC/CAM

numbers indicate a specific alloy mix.
7xxx series adds Zinc to the alloy, none in 6xxx
6xxx is trace Si [ .6%], not found in in 7xxx.

[Ref Machinery's handbook 23rd Ed, pg 604, nominal compositions]

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