Which is the heavier bike frame alloy or aluminium?

Answer 1

It depends on the bike. Common frame materials are: steel and its alloys, aluminum and its alloys (magnesium, titanium, etc), and carbon fiber. Even within these materials there is a huge variation. Old mild steel frames can weigh 20+ lbs with no wheels, seat, bars, crank, or gears, while a low cost CroMoly steel frame may weigh 10 lbs, and a high end triple butted steel frame made from engineered steel like Reynolds 953 can weigh as little as 2.5 lbs without a fork. Aluminum frames can be as light as or slightly lighter than steel, but a department store steel frame may weigh 10 lbs and a dept store aluminum frame may weigh 8. Titanium, magnesium, and other alloys are generally 80-90% aluminum with other materials to make the material stronger so that the tubes can be thinner. A frame in aluminum or titanium can get as light as 2 lbs sans fork. Carbon fiber is the champion for lightness, but even then it can vary. You will probably never see a 10 lb carbon frame, but you may see some 4 lb versions, so a top end steel frame would be lighter. High quality carbon frames without fork and using no inserts can get below 2 lbs. Riding characteristics are different for all of the materials, steel tends to be a smoother ride than aluminum, and carbon can be engineered to give a smooth ride as well. Steel tends to be more forgiving of overstress, like a crash. Carbon fiber can fail catastrophically in the right (or wrong) conditions, and send splinters of carbon flying. Honestly, when you get to the top tier of any material, frame weight is less of an issue than components and frame feel. You will probably not be able to tell the difference between a 3 lb frame and a 2 lb frame, especially after you put 10-15 lbs of parts on it, and a 150 lb rider. That added 0.62% of weight will have less impact than about a dozen other factors, from the spring or softness of the frame (helping or hurting your pedaling force) to the rolling efficiency of the chain (anywhere from 97-99%, a 2% gain over a .6% gain).

Answer 2

Usually they're the same thing.

Perfectly pure aluminum is rarely used in any kind of construction due to how soft it is. What you usually see is aluminum alloys. They're mostly aluminum, but have a few percent of other metals in them as well.

Some people refer to these as aluminum, as that is the dominating part while others call them alloy.

The general rule however is that the fit and the quality of the bike is more important than the material. Doesn't matter if you've got the bike of champions and it's the wrong size for you.

Answer 3

Alloy 7075 is often used because it is weldable. It's also very strong.