List the pros and cons of using steel titanium scandium and carbon in bike frames?

Answer 1

Steel is stronger; aluminum is (much) lighter--and still pretty strong.

Steel is stronger and weighs more. Aluminum road bikes are super vibrated and it can hurt your hands and cause carpal tunnel (carbon fork and handle bars dampen it). Anyone who has rode a carbon fiber bike knows that its the upgrade from steel. Steel however, is effected by gravity differently in comparison to aluminum. Gravity pushes down on your steel frame on long descents that it actually causes the frame to flex under the force. Here's a way to put it, Aluminum feels dead and steel feels more lively because it isn't as ridgid. A really cool benefit to a steel frame is if you get in a crash and damage it you can have it fixed easily compared to aluminum and especially to Carbon Fiber

Answer 2

Steel:

• Cheap
• Easy to manufacture
• Quite forgiving WRT impact and handling damage
• The material properties, stiffness, springiness etc make it easy to build a proportional frame
• Weight is the main downside
• Rust is a secondary downside

Titanium

• Better strength-to-weight ratio makes it possible to build lighter bikes
• Doesn't rust
• Expensive
• Harder to manufacture
• Another stiffness/springiness ratio prompts the use of different tubing diameters to get a good ride

Scandium frames don't exist. It's a marketing ploy.

What does exist is aluminium alloyed with scandium.

The functional difference between an aluminium alloy containing scandium vs plenty of other aluminium-based alloys is marginal-to-none.

Carbon fiber

• Very good strength-to-weight ratio
• Easy to shape and steer the properties by varying the weave direction and number of layers. It's possible to get the strength just where it's needed.
• Allows you to build very light bikes
• Expensive as material
• Expensive, time consuming to build with
• Tend to be sensitive to handling damage