I use solid works nearly everyday at work. It would be a great package for frame design (its good at doing solids and extrusions with varying profiles ie.: easton rad style tubing, the surfacing side is limited but getting better). Solid works also allows for live linkages, you could deisgn a full suspension from and then easily see how it will react, change some dimensions and see the difference. New version alos allow you to restrict movements due to applied force , (ie spring rates etc). There are heaps of decent CAD packages out there, many can be obtained as trial or educational type copy for free, each package does differnet thing better ( or worse). I use solid works as it allows parametric control ( change one part in an assembly and other parts related to it will all update automatically). This package also allows 3D parts to be exported dirrectly to formats that alow production using CNC etc, good for bike parts.