Industrial Design, perhaps with a business minor (if you plan to market them yourself ) ?

+1 to tri-ac. A mechanical engineering degree is much more marketable and broad based, however you probably won't get into as much fluid dynamics (at least that isn't inside pipes, pumps, and turbomachinery) as you would with an aeronautical engineering degree. At the University of Wisconsin (GO BADGERS!) that's in the engineering mechanics department. If you are really interested in the aerodynamics portions, probably look to schools that have a close relationship with companies like Boeing, Lockheed-Martin, etc since they'd fund a lot of research. Good luck.

Braden
Chemical Engineer

I have a masters degree in mechanical engineering. I mostly work in machinery and manufacturing. Mechanical engineering is probably your best bet to work in this field.
Low speed aerodynamics and compressible fluid flow are good upper level undergraduate classes and graduate courses for your interest.

I would also high recommend composite material design and some sort of metallurgy, as most frames are fairly exotic in their material. A familiarity with bearings and general machine design will also be helpful.

Occasionally I put a design on paper and put a plan together for execution, but so far I have not followed through...too busy training. :)

+1 Coming from somone who can't stop going to school, and although Engineering out of my perview, I'd say Mech Eng undergrade followed with a joint MBA/JD (MBA for marketing, finance, accounting, etc. JD for contracts, mergers, and liability issues. I'm sure frame fabricators spend just as much on R&D as they do defendling lawsuits). You're looking at seven to eight years and well over $100k in tuition.

I would go to the careers section of Felt, Specialized, Cannondale and see what they ask for. From what I remember it would be a BS in MechE. Don't Worry about the MBA, JD, etc... I would try to intern at a bike manufacturer while you are in school. I would minor in Taiwanese too!