A bicycle costs anywhere from $250-$9,000 depending what type and quality of bike you want. A utility bike from a department store might cost $300-$500, but experts caution that it will be quite a bit heavier and not as well constructed as other bikes. For a durable, lightweight bike with front-suspension and decent parts, it’s reasonable to pay $750-$1,200. You might be able to pay slightly less, but expect to need some repairs after several months of heavy use.
Any bike that gets ridden seriously as transportation or on long rides needs at least a basic tool/emergency kit, and the knowledge to use it, unless the rider is always in a position to call a friend with a car or a cab when their bike needs a quick fix on the road. If you never travel more than a few miles, this can be overkill, and calling a friend or a cab may be just the ticket, but if you want to be more self reliant, this is something you should seriously consider. This list may sound like an awful lot of stuff to carry, but really, it only weighs a few lbs and fits in a small, under-seat bag that comes off quickly so I don’t have to leave it with the bike if theft is a concern. If you always carry a regular rack top bag, you can also just put all this in a small nylon bag and throw it in there, but I prefer an under-seat bag.
To pick the right size bicycle, you want to measure your height, and specifically your inseam (inside leg), in proportion to the size of the bike frame. The inseam measurement determines the seat height, or the “stack.” Next, you must calculate the “reach,” which is the horizontal distance between the bottom of the frame and the head of the bike -- or, in layman’s terms, the distance between seat and handlebars.
Modern bottom brackets use a sealed bearing type construction that keeps water and debris locked out, so they seldom go wrong. Maintenance is impossible so they need replacing when they do wear out. Older style cup bottom brackets need to be re-greased every now and again, and occasionally will need to have their bearings replaced. There are a lot more teeth on the chainring cogs than those on the rear cassette, so need changing less regularly. Cranks usually a solid one piece construction so there is not much to go wrong.