Now that you have defined just what you want to do with your bike and consequently what type of bike you will need, you should consider any goals you may have and inventory your skills, energy level, budget, and the risks. This is reality check time. Bicycling has its risks just like any other activity in life:
- falling off
- colliding with a pedestrian, cyclist, automobile, etc.
- being struck by another cyclist or automobile
- being stranded somewhere with a flat tire/broken whatzit
- having your bike stolen
- being ticketed for riding on the sidewalk / no bike zone (this is unlikely unless you live in an area with very active cycling community or draconian anti-bike culture)
- getting lost
Of course you know that bicycling has its benefits, or you wouldn't be reading about how to buy a bike. If you want a little reminder of some of those benefits, feel free to refer to my manifesto on why i bike.
Now, with motivation restored (right?!), consider whether you know how to ride a bike, whether you are willing to learn, under what circumstances you would realistically get it out and ride it (hot days, cold days, dark nights, drizzly rain, drifting snow, fire and brimstone?), how long you would ride it each time, and whether you are willing to acknowledge and take precaution against the risks. Are the harsh realities in line with your dreamy expectations? You should also consider how much you can afford to pay up front for a bike, how much time and effort (and technical inclination) you are willing to put into owning it, and how much you will be able to budget each year to maintain it. Prices and service costs vary by locale and season, but a realistic expectation for minimum costs (if you are willing to put in time and sweat) is approximately $125 for a decent used basic transportation bike, another $60 for important accessories and safety equipment, and annual maintenance costs of around $40. If you are planning to get a used bike, but to rely on your local bike shop (LBS) for the purchase and most of your bike-related needs, you will probably need to plan on 2-3x that much. At the opposite extreme, if you are going to outfit a late model, shiny new bike with all the bells and... horns?, you could be looking at several grand. (And God bless you souls that make budget biking possible by covering the depreciation on shiny new bikes and subsidizing the LBSes.)
Depending on your approach to it, bicycling can be an extremely affordable source of transportation, in addition to an enjoyable one.