Soapbox - GoKart material - Bamboo or steel?

Question

I am building a soapbox (go kart) and I am planing on what materials I could use for the frame and the chassis. I have thought about using bamboo or steel.

Steel is normally the go to material when building the chassis and frame. However, I am starting to think bamboo may be a better choice. My reasoning is that:

• Bamboo is less dense than steel, this makes the structure lighter and could enable it to go faster.
• It is cheaper than steel. This leaves room for prototyping and allows me to iterate my way to perfection.
• More flexible than steel this could be good as the go kart will jump over bumps and slides.
• No welding would be needed.
• Depending on the type of steel used, bamboo can have a higher tensile strength than steel.
• More eco-friendly.

Also, it is possible to make a bamboo composite that produces a stronger bamboo based material.

Could you let me know your thoughts on what I should use: steel, bamboo or something else?

Answer 1

I think the only way to decide this is to make a preliminary design of your cart - twice, once with steel, once with bamboo. You don't need to engineer every detail, but you need to have close look at the critical issues:

• How to connect individual members (with the tools and skills you have access to)
• Cost
• Weight, center of gravity
• rigidity or stiffness of the whole structure and individual members
• How does bamboo fail vs. steel?
• Safety or which material is more likely to impale the rider in case of accident

In my experience, some issues only show up in manufacturing/building, but many issues will become apparant the moment you make a decent drawing of your design.

Answer 2

The idea of bamboo is an interesting thought, but ultimately steel will be a better material to use.

You want a low center of gravity on a GoKart, and using bamboo will raise the center of gravity and make it easier to flip over when approaching turns. The connections would be your biggest problem. I design wood structures everyday and exposed connections are often large because thru bolts are required for larger forces. I could see you running into issues trying to coordinate the frame intersecting and getting the strength you need in shear, flexure, compression, and tension with a bolted connection rather than a welded connection.