What do you use the bike for? It's a long aluminum frame - for god's sake - DO NOT RIDE STREET ON IT AT PERIL FOR YOUR LIFE!
No seriously, the bike is designed as a lightweight racing frame, not as a street/dirt/vert/flat bike. I might trust that bike for some flatland, but the design is completely wrong for flatland.
For the cranks... What kind are they? What brand? It doesn't really matter what they are made of if they work though. They are either forged steel, tubular chromoly, or aluminum. If you take a picture of them and post it then we would have better luck telling you what they are.