So I currently have 2 bikes:

1. a generic mountain bike with heavy-duty off-road tires. It's only used for trails and in the winter.
2. a Giant Seek 2 - road-oriented hybrid. I put a lot of miles on it riding around my college campus, but it's almost too easy to ride. I can basically cruise 75% of the time.

EDIT: I live in a relatively urban area with a number of suburbs around. So it's a lot of stopping and starting; no long treks down a trail.

Seeing as I love biking and need the exercise, I'm looking into a 3rd bike exclusively for working out. The more difficult it is to pedal, the better - I'm aiming for pure cardio here, so I need to get my heart rate up.

I've decided between two types of bikes: a fixed gear or a cruiser. Keep in mind that this bike is temporary; I'm going abroad next August and will be selling all 3 bikes at that time.

Pros and cons of each:

Fixed gear
+ Bike only moves when you pedal
+ More effective on roads
- More expensive
- Slightly more difficult to find
- Not as good off-road or in bad weather

Cruiser
+ Still pretty difficult to pedal
+ Looks damn cool
+ I can easily buy a decent quality one at Target for ~$130
+ Can ride off-road and in bad weather (at least better than a fixie)
- cruising is still possible (pun intended), so maybe less of a workout?
- could be harder to pedal fast, which may or may not be necessary to increase heart rate (for cardio)


Any thoughts? I'd really like to go for the cruiser, but I am open to be convinced otherwise. Thanks.