Alumunium 6061 -- 7005

6061 Vs. 7005 Aluminum for Bikes

You can’t tell the differences between the 6000 series and the 7000 series of aluminum bikes by looking at them. But the compounds and qualities of the aluminum are different. They are different to allow for more affordability, to give the buyer a choice between certain aspects of performance versus cost.

1. Formula

   • When aluminum is cast, it is mixed with other minerals to impart different qualities to the metal. 6061 aluminum is cast with magnesium as its primary additive. 7005 aluminum is cast with zinc as its primary additive. Both formulas have different qualities of lightness, strength and cost. 6061 aluminum is cheaper, thus making a bike built from it more affordable. It’s more costly to use zinc as an aluminum additive, making the 7005 series more expensive.

   Strength

   • While the strength of most bike frames is not much of an issue, when bike frames continue to get thinner and lighter, strength can be a deciding factor. Magnesium frames are not as hard as zinc frames. This makes the 7005 the better choice if your frame is extremely light such as on some elite road bikes. For mountain bikes that have a bigger tube design, 6061 aluminum is strong enough.

   Ride

   • Due to its inherent hardness, 7005 aluminum bikes feel rougher when you ride them. You might not realize it, but bike frames bend when you ride the bike. They absorb bumps and road vibration. The 6061 alloy is softer, making the bike’s ride more comfortable. The stiffness of the 7005 frame make its ride more harsh. For smoother riding bikes, choose 6061 frames.

   Appeal

   • If you care about fashion, keeping up with the latest trends, or want to have the highest priced aluminum bike, you would want to choose the more expensive 7005. 7005 bikes also have more expensive components, and the bike will probably be slightly lighter due to this fact alone. A 6061 bike will cost hundreds of dollars less, though, and will do virtually anything a 7005 bike can do.
     The biggest difference is WHO is making the actual frames...
     

     and what facilities they have for production. 6000 series alloys require more post welding procedures to have adequate strength for usage as a structural material than 7000 series alloys, but they are slightly easier to work with, have a VERY slight (like 0.002 pounds per cubic inch) density advantage, and somewhat better corrosion resistance. On an aircraft you'd typically see a 6000 series alloy used for the external skin and a 2000 or 7000 alloy used for internal framing and structural supports. Simply using one alloy or another is not going to make a frame lighter or not. That depends on the frame designer and how he manipulates the tube sizes, wall thicknesses and so forth.