The "best buy" bikes are mountain bikes in the $400 to $600 range. Many of the bike messengers in Houston ride such bikes, because they are both fast and durable on the bombed-out wreckage that Houston calls roads.
In that price range, you get a bike that is tough enough to ride on trails, yet that can converted to street use by mounting lightweight "slick" tires. Their geometry makes it easy to add a rear rack and saddle bags, so you can even use a mountain bike for a day or two of touring.
A road bike or touring bike makes sense if you plan to ride a hundred miles a day, or take two hundred mile week-end tours. But, if most of your rides will be 20 miles or less, a mountain bike will do fine.
The "brand name" is not as important as the shop you buy from. Buy from a shop that takes the time to really get a bike right. The difference between a bike that is "almost" tuned and wheels that are "almost" true is the difference between a great cycling experience and a mediocre cycling experience.
Riding on the sidewalk? I'm currently in San Antonio, where in newer neighborhoods you have a choice of riding either on a freeway feeder road, or a six lane road, each of which have bumper to bumper traffic moving at 40 mph to 60 mph. The lanes are about six inches wider than an SUV, making it impossible for a vehicle to pass a bike without moving over to the next lane, something no "true" Texan would ever consider doing.
As a result of such poor road design, many bike commuters ride on the sidewalks that are along such roads (rare), or on six inch wide paths worn in the grass along such roads (more common). And, mountain bikes are perfect for riding on those narrow paths through the weeds.
I often read posts in "Bike Forums" from guys who claim to ride their bikes on freeway feeder roads. I've never seen the same rider attempt that feat twice in Houston or San Antonio...very quickly, common sense overcomes their "I have a right to ride anywhere I want" attitude.
Last edited by alanbikehouston; 10-04-07 at 09:40 AM.