Folding Bikes + exercise

[Kamui712]

I'm interested in buying a bike for exercising (alternative to running). Because of space, storage, and theft issues I'm considering buying a folding bike like these:

http://en.wikipedia.org/wiki/Folding_bicycle

I'm wondering what your thoughts are on these bikes are more than just casual commuters and more for exercise but NOT competitive cycling.

Thanks!

[RayBot]

im not a an expert on any bikes at all, but those don't seem like anything more than a casual commuter.

[hamsup]

i found folding bikes to be completely inefficient... if you buy a bike where you can take off the seat post, front wheels and rear wheels.. it takes us just as much space (well just a bit more).

I say buy a used road bike or commuter bike off craigslist.. if it does get stolen.. it wont be a HUGE lost.