Me and my friends will be building a big ramp for jumping bikes into the river. At our lowes they have Top Choice Green Douglas-Fir Lumber, Precut Kiln-Dried Hem-Fir Studs, and Select Kiln-Dried Hem-Fir Studs. Those are 2" x 4"s. Which is best to use for frame of a big bike ramp? Wood Wood Lumber Wood