chemical rocks are formed by what that grow out of a situation?
Crystals that grow out of solution/precipitate. Banded iron formations (iron oxides), chert (silica), dolomite (calcite), limestone (calcite), just to name a few. There are many.
You don't. In spite of what people think, smaller wheels have no speed disadvantage over larger ones. They also have the advantages of being faster at accelerating, although they are not good on bumpy surfaces.
an engineer can give better specifics, but the 18 wheels will require considerably more work, assuming the same gearing ratios. folding bikes are ideal for those who have minimal storage space. I for 1 would hang my bike on a wall, rather than some fuddy-duddy rembrandt
