Today's urban bicycle commuter has to surmount many challenges. There are the frequent road irregularities, due to unkempt roads during this recession. We also have the oily, wet, and snow covered pavement with which to contend.
In addition to road conditions, there are the inconsiderate and absent minded automobile drivers who constantly cut us off and open parked car doors as we're passing. There are the ever-increasing texters, who only focus upon the road between letters. Then there are the taxi cab drivers who I am convinced, are all on contract to kill us! That's not to mention the large trucks who suddenly swing out right, only to turn left. I think they're out to get us, too!
Today, the commuting cyclist needs a bicycle that is durable, nimble, and versatile. Most road bikes, don't qualify, as their tires are usually too narrow for the daily road irregularities and riding while in the drops does not place a commuter in a very good position for traffic observation.
Double suspended MTN bikes are overkill on the weight, and make for very inefficient, energy absorbing, commuting monsters.
However, most Hybrids and Hardtail MTN bikes with rigid forks, make great commuting bicycles. Their handlebars allow you to sit more upright where you can more easily view both traffic and pedestrians, alike. Their tire widths are generally wider than any performance road bike. That means that they can better grip the road and are less likely to suffer flats, as well. You can also more easily install a rack, or perhaps even fenders to a hybrid or a MTB, due to more available eyelets.
Then there's the Touring and Cyclocross bicycles. These bicycles, when equipped with cross brake levers, make for the ultimate in commuting. While your hand position is firmly placed upon the hoods, you can more easily observe traffic. Since, you have cross brakes, hands on hoods presents no safety issues with braking. These bikes typically come with much wider tires, too. That's especially so when your Touring or Cyclocross bike comes from either Surly or Salsa, the QBP bicycles. They are usually at the top of my list when considering commuting conditions.
My favorite Touring/Commuter of all times is the Surly Long Haul Trucker.
It's a veritable truck when it comes to speed, but for the money, you just can't beat it for loaded touring and when unladen, it can slice right through all of the urban road irregularities, due to its wide tire option.
It's quite a versatile bike for the money...
If I lived in Chicago, Florida, or New York City, I'd commute almost exclusively on a single speed, as long as they'd have cross brake levers!