Author Topic: Aluminium Alloys in Flatland  (Read 9138 times)

Offline Norky

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Aluminium Alloys in Flatland
« on: March 27, 2009, 09:14:38 AM »
I've been thinking about the stresses flatland cause, and compared to MtB(where they do use Alum. alloys) it seems pretty stressless, on the bike.

Do flatland companies make a 7005 or 6061 bike? i believe the answer is no.

why don't they?

discussion encouraged.

Zac

Offline mare

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Re: Aluminium Alloys in Flatland
« Reply #1 on: March 27, 2009, 09:50:04 AM »
hm...? interesting

Offline Norky

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Re: Aluminium Alloys in Flatland
« Reply #2 on: March 27, 2009, 09:53:03 AM »
What i'm asking, essentially, is why it's not used in flatland.

is there some detrimental flaw with alloyed 6061 or 7005 aluminium that will make it impossible to flat on?

or strength issues?

byke

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Re: Aluminium Alloys in Flatland
« Reply #3 on: March 27, 2009, 10:29:49 AM »
What i'm asking, essentially, is why it's not used in flatland.

is there some detrimental flaw with alloyed 6061 or 7005 aluminium that will make it impossible to flat on?

or strength issues?

Yes,
alloy is generally too temperamental  in terms of yield strength and aging.
This causes the stress factors of the material to be to uneven and thus result in a poor flatland frame due to the multiple stresses from many areas from various angles of riding.

Offline Norky

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Re: Aluminium Alloys in Flatland
« Reply #4 on: March 27, 2009, 10:47:04 AM »
A -T6 (Heat Treated and artificially aged) Alloyed 6061 is shown to have a very similar yield strength to 4130 Chromoly Steel.

Offline Norky

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Re: Aluminium Alloys in Flatland
« Reply #5 on: March 27, 2009, 10:48:32 AM »
But thankyou Byke, for a straightforward answer.

Aaron Frost

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Re: Aluminium Alloys in Flatland
« Reply #6 on: March 27, 2009, 01:18:33 PM »
there is a significant difference between 4130 and 6061 aluminum alloy, especially when you factor in heat treating. The most important difference is fatigue life. Mark and I have both been down this road with less than acceptable results. To achieve an acceptable result in terms of durability, using 6061 or even 7005, you would have to use a thicker wall tube; thus, no real weight savings. When looking at materials, strength to weight ratios will tell you a lot. Hope this helps, take care - Aaron

Offline Norky

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Re: Aluminium Alloys in Flatland
« Reply #7 on: March 31, 2009, 11:59:01 AM »
Thanks Aaron.


7075 alu. would be good, the NASA alloy. But that stuff costs immense amounts.

so the thickness would mean there would be no real weight saving... did you mean off Hi-Ten steel, or 4130 Chromo?

Offline Paradoxium

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Re: Aluminium Alloys in Flatland
« Reply #8 on: March 31, 2009, 12:16:03 PM »
Thanks Aaron.


7075 alu. would be good, the NASA alloy. But that stuff costs immense amounts.

so the thickness would mean there would be no real weight saving... did you mean off Hi-Ten steel, or 4130 Chromo?

Both. The biggest difference between chromoly and more common metals such as high ten steel is the absence of chromium and molybdenum {in hi ten}. These 2 key ingredients are what makes chromoly stronger and more durable, thus allowing thinner tubing than say high tensile steel.

6061 and 7075 is already used commonly in flat and BMX in  general. Its common in stems, pegs, hubs, seatclamps, barends, seatposts, gyros, brakes, sprockets etc.
It wont be used in tubing because it will need to be alot thicker guage, therefore defeating the purpose of its use. Our chromoly frames are doing fine. Its only when weight boundaries are pushed too far and we get very thin tubing do they fail.

Its very easy to build a light bike with parts straight off the shelf. Most of todays parts are not heavy anymore, unless you buy a cheap complete.


Offline Norky

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Re: Aluminium Alloys in Flatland
« Reply #9 on: March 31, 2009, 12:34:02 PM »
I was speculating it to be cheaper to import alloyed Alu. through a guy i know, and weld it at home; Knowing it requires alu alloy and MIG welding, and lots of practise.

so you dont think that a frame would be feasable with Alu. atm?



Offline Paradoxium

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Re: Aluminium Alloys in Flatland
« Reply #10 on: March 31, 2009, 12:36:41 PM »
I was speculating it to be cheaper to import alloyed Alu. through a guy i know, and weld it at home; Knowing it requires alu alloy and MIG welding, and lots of practise.

so you dont think that a frame would be feasable with Alu. atm?




Its far easier to just buy a secondhand frame from the marketplace. We have a marketplace on flatlandaustralia too, but its a bit quiet. You just gotta keep your eyes on the lookout.

Offline EZChris

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Re: Aluminium Alloys in Flatland
« Reply #11 on: March 31, 2009, 12:37:32 PM »
I've been thinking about the stresses flatland cause, and compared to MtB(where they do use Alum. alloys) it seems pretty stressless, on the bike.



Commom misconception - the stresses put through flatland parts are quite severe - the problem is with flatland you arn't just putting pressure on from one direction like MTB and other forms of bmx, you are always applying force from awkward angles and directions that are changing rapidily.
Proud member of the Spaff Cartel.

Offline Norky

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Re: Aluminium Alloys in Flatland
« Reply #12 on: March 31, 2009, 12:38:41 PM »
you have a point..

how about forks?
would they be feasible?

Offline Paradoxium

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Re: Aluminium Alloys in Flatland
« Reply #13 on: March 31, 2009, 12:47:08 PM »
you have a point..

how about forks?
would they be feasible?

Any type of al fork always snap in flat and BMX in general.
Racing maybe, they have even used carbon fibre and magnesium amongst other ingredients.   ^_^
« Last Edit: March 31, 2009, 12:49:32 PM by Paradoxium »

Offline Norky

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Re: Aluminium Alloys in Flatland
« Reply #14 on: March 31, 2009, 12:55:55 PM »
wow.
You guys here, are ace to bounce idea's off.

so no forks, no frame....
Bars?