Your car needs bumpers!
Paraphrased, from the Rules: “All teams are required to have front and rear bumper-like structures that are between 4 and 6 inches from the ground. The bumpers should be firmly attached to your frame. Teams should soften up the edges of the bumpers in some way, perhaps using strips of rubber. The bumpers should be blunt, simple and not a means to make a kebab out of somebody.”
After Maker Faire Detroit 2017 there has been discussion about using wood for bumpers rather than metal. We had multiple cars destroy the water-filled barriers and metal has a way of tearing through things, which is not something we want. Wood can be hard, but also can break, it's a trade-off, right?
Square cut tubular bumpers can be made completely safe by welding black iron pipe caps onto the ends of the tubes. The pipe caps can be found at any hardware store and are cheap. They are round and blunt and will not tear through the barriers and are safe for collisions with other karts.
If you are attaching a wooden bumper to your car, DO NOT USE SCREWS. When your bumper breaks or falls off, it may have screws sticking out of it. This is bad for tires and people! Use bolts instead. They are less stabby.
Cartastrophe has pretty much treated their front wooden bumper as a consumable item, and replaces it all the time. This seems to be a good approach. Cartastrophe says: “We have 4 bolts to hold on the 2×4. A new bumper is always just a matter of 1 cut, and 4 hole drills.”
Basically we're after rounded and/or breakable bumpers that will not harm things and/or people.
What else you got? Add more bumper info here!