2

I saw a crankset made of 2014-T6 aluminum alloy (so it was claimed).

I read that this alloy is somewhere in between 6061 and 7075 in terms of strength. I also learned that it is also more brittle than both 7075 and 6061. But the thing that caught my attention was its bad corrosion resistance. According to the Wikipedia:

The corrosion resistance of this alloy is particularly poor.

Hence I'm curious if it is worth to get a chainring made of 2014-T6? I am more interested in its durability as I am not into any competitive riding.

Other than from corrosion, do I need to worry about other types of failures?

Improve this question
3
  • 3
    Honestly, chainrings and cranksets (even dirt cheap ones) last a long time, provided you change your chain when worn. I don't think there's really anything that's a real threat to road riders; mountain bikers might bend a ring in a crash but that's luck of the draw anyway. Crank failure (usually closer to the pedal) does happen but its fairly rare.
    – Batman
    Dec 28, 2019 at 13:39
  • 1
    "Corrosion resistance" compared to what? Alloys designed to be immersed in salt water for 100 years? Compounds for holding HF?
    – Andrew Henle
    Dec 28, 2019 at 14:49
  • 1
    If you are interested in the chainring's longevity, get yourself a steel one. Aluminum alloys do not rust, they oxidize. Stainless steel is also resistant to rust, and "non-stainless" steel, while rusting, will still be mostly fine for a long time. Unless you live near a salty ocean, that is.
    – Grigory Rechistov
    Dec 28, 2019 at 16:20

2 Answers 2

Reset to default
4

Aluminum alloy 2014 is often used in the aircraft industry for structural support beams and the auto industry for truck frames. See metallurgy reference. It outta be just fine for a chainring.

Alloy 2014 T6 has a Tensile strength (ability to resist stretching forces) of about 483 MPa which is comparable to structural steel and much higher than 6061 T6 aluminum's 300 MPa. This strength is achieved with a tremendous weight savings (as opposed to steel). All this is to say that it appears the 2014 aluminum is stiffer than some other possible materials which is beneficial in a crankset so that more pedalling power goes to crank rotation and not lost through material flex.

Regarding cracking, that increased susceptibility of 2014 is confined to manufacturing processes such as welding, where special support of the piece is required, or where bending the alloy is needed, avoiding sharp turns is necessary. Oxidation prevention in pieces made of 2014 alloy is carried out by bonding a thin layer of pure aluminum (a "skin") or some form of painting, anodizing or powder coating to the outside.

Improve this answer
4
  • 1
    For the nerds: I realize it might be a stretch (ha!) for some of you to accept my paragraph that relates Tensile strength to material stiffness and then tie it to economy of energy in the activity of bicycling. Especially considering that the Watt savings in using steel chainring vs. aluminum is likely measured in the thousandths of Watts, if it can be measured at all except in comparing the results of equations on paper...
    – Jeff
    Dec 28, 2019 at 20:15
  • 1
    ...While I cannot know the mind of the engineer and do not care for the marketing person's hype, I believe the alloy was chosen for the chainring based on 2014's availability (usually as flat rolled sheets. Easy to stamp out a few chainrings), ease of machining for the teeth profiles, and the physical properties, especially stiffness and strength to weight.
    – Jeff
    Dec 28, 2019 at 20:16
  • Ultimate tensile strength and stiffness are two different things. 2014 may be stronger than 6061, but not at all stiffer. You have to compare the Young’s modulus for stiffness.
    – Eric S
    Dec 31, 2019 at 15:07
  • Young’s modulus == modulus of elasticity.
    – Eric S
    Dec 31, 2019 at 15:09
3

There is no real corrosion resistance difference among the three . 7 year atmospheric exposure ( Kure Beach NC) shows slightly less weight loss for 6061; BUT , because it is difficult to measure corrosion in Al because of pitting, the tensile strength loss ( of thin material) is measured. 2014 and 7075 lost zero % while 6061 lost 0.007 %. So no practical difference. All aluminum alloys have the same stiffness , about 1/3 the stiffness of steel. All the listed alloys have practically the same ductility ( 10 to 12 %). 6061 has about 2/3 the strength of the others. If any mechanical contact wear is involved , it is hard to imagine any aluminum could come close to steel for wear resistance. When heat-treated to a modest level like HR C 40 ( 200,000 psi tensile ) steel has the same strength/density ratio and 3 X the stiffness and much better mechanical wear resistance.

Improve this answer
4
  • This is IMHO a better answer than the accepted one. You might offer that 6061's main attribute is that it is easy to weld.
    – Eric S
    Dec 31, 2019 at 20:19
  • Although aluminum weld metals are normally very low strength. Tried to measure aluminum weld once and the consulting lab could not do it ; they said it was like pulling "bubble gum".
    – blacksmith37
    Jan 2, 2020 at 15:23
  • I'm not an expert, but aluminum is welded effectively all the time. Pretty much every aluminum bike is welded. It is, I believe, a lot more technical than welding steel and you should do a full heat treatment after welding.
    – Eric S
    Jan 2, 2020 at 17:25
  • We were welding large aluminum exchangers ; I forget the alloys ; I agree with the right filler metal and heat-treatment will have good strength.
    – blacksmith37
    Jan 3, 2020 at 20:12

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.