There is bikecad
http://www.bikeforest.com/CAD/
And Rattlecad
If you are just making a few frames it is easier and better in a lot of ways, to draw them full size on paper.
I design in old school 2d, one really needs relatively little info, and it's all there. I am a little leary of simplified systems since they do what they want to do, while I do what i want to do.
For a pro bikecad is a good tool, and a good promotional tool. I don't like their business piece though.
Another problem with good bike cad is that it does your thinking for you, while there is no substitute to actually knowing what needs to go where, and filling in the blanks from one's own knowledge base. If one doesn't know what stuff goes where it's as well to find out. There are a lot of little details, like the actual shape of the actual parts I am using or making, that I want to control.