Grillparzer

Pros:
Money
I got lots of cudos at work for dedication when I rode after Snowmageddon and more when I showed up the day a hurricane hit. Probably should have pointed out that the Metro wasn't running.
It's faster, I ride eight miles in forty-five to fifty minutes. Using the Metro system, a bus ride and then the subway, takes about fifty-five minutes to an hour five.
I've got a good route, Google Maps bike option picked an excellent option for me. I ride from Silver Spring, MD to downtown D.C. every day and about half of my ride is quite neighborhood streets. I start work at 7:00 AM so I beat a lot of the rush hour stuff coming in to town.
Bike lanes are new to me and cool as a Maine moose.
I enjoy the hell out of it. More smiles per miles they say.

Cons:
Right now, I'm only doing mornings. I haven't decided whether I want to try D.C. at full rush hour yet.
It doesn't matter where I live or where I'm riding to, I'm always down hill from my destination.

getyourcrayon

Pros:
-Endorphin rush! Precious little exercise promotes this like cycling.
-Leg muscle expansion xD
-The pride in my increasing endurance
-Coworkers impressed by my bike
-My current bike is currently just right

Cons:
-The "you're weird"attitude I get is only amusing the first few times
-@$&# high speed high traffic high stress roads and my inability to avoid them completely bcause the people who designed these roads are morons
-Drivers honkkng atme, even if it isn't mean honking.
-I don'thave a quick and easy way to put stuff on the bike yet
-Limited ability to use my u lock
-Too many damn cars. Way too many damn cars.
-Most attempts to get to a place the back way to avoid traffic I get lost at first because my sense of direction sucks.

My cons list is longer but that endorphin rush s worth 8 extra points at LEAST.

The Chemist

Pros
- Morning riding wakes me up
- Good exercise
- Good views
- Avoiding the crush on the Metro

Cons
- Takes more time to get ready to go in the morning/afternoon (particularly having to change to/from work clothes at work)
- Shanghai drivers
- Having to take the ferry to cross the river
- Flat tires (admittedly not a common problem, but it does suck having to fix flats on the side of the road)

wsgts

Thanks for posting this, I guess I a little different than most on here:

PROS:
Health and time: Gives me two hours a day of working out, and only uses about 1 hour to do it. By this, I mean it takes 30 minutes to commute to work via car, therefore costing me one hour a day round-trip. It's takes 1 hour to Commute via bike, therefore 2 hours total, but I was going to burn an hour anyway. When I get home from work, work is done as well as my workout. I'm fully ready to spend time with wife and kids.
Other reasons: it does save money, is environmentally responsible, and won't have me stuck in traffic. None of which I give a hoot about.

CONS:
- Getting up early enough to get to work on time.
- Changing clothes at work and carrying clean clothes to work everyday.
- Everyone at work offers me a ride home, even though they know I am doing this health reasons.

lanahk

Pros:
Get exercised/energized in the morning.
Save on gas. I only had to fill my truck twice last summer.
Have an excuse to buy bike stuff as long as I'm riding.

Cons:
Hills, hills, hills.
Soccer moms in SUVs and teenage rednecks in pickup trucks.
Rain and snow.

whk1992

Pros: Faster than walking (I don't drive, so my only options are either walking or cycling), which let me travels around my school during lunch breaks. Oh, and I can stay longer at school. Commuter buses on campus stop servicing after 6pm. With my bike, I may get to the freeway and ride home as late as midnight.

Cons: My jeans are always soaking wet in winter. Other than that, I don't feel any problems.

Chesha Neko

Simple. There are people who bike commute and are therefore awesome. Then there is everyone else.

vol

Many pros which you all agree so I won't mention, but also: less chance to get flu or other contagious diseases from crowded busses or subway trains, less worry about terrorist attacks aimed at mass transportation (I'm in NYC )

Cons: Dangers on the road from vehicles. Sometimes the weather does not cooperate. Parking can sometimes be a problem especially considering possible thefts.

sbslider

Ridefreemc

Pros:

Standing next to someone my age (and often much younger) and they say/ask "you look like you are in good shape, what do you do?"
Being about the same weight now as I was 30 years ago (this saves on clothing costs as well since I can wear things longer and get more use out of them).
Not getting sick (not sure if this is due to commuting, but I'll take it)
Looking at my beautiful bike while I'm at work - dreaming of where I can go next weekend or what side-trip I might take on the way home tonight.
Having an excuse to post and read on the Commuter forum.
Getting to know people now and then on the commute (never ever happen in the auto)
Saying "yes" to just about any activity that I get asked to do by friends because I am in fairly good shape

jpfankuch

Pros: The habit of biking to/from work instead of the usual car ride helps reinforce the larger habit to think about the best solution to problems instead of just the easiest one. I get a chance to say hi to the horses in the field on the way.

Cons: Some days the weather changes during the day and you end up biking against the wind both ways! That really bugs me. It never seems to work the other way too.

DntWorryB.Happy

Pros:
GREAT stress reliever
Exercise
Get to see the scenery and enjoy the nice weather

Cons:
Weather isnt always nice
******* drivers
flat tires

shaypop

pros

i'm on a bicycle. anyday on a bicycle is a good day.

cons

while i appreciate the concern, when the wife and boy show up at the end of my shift to give me a ride home because it's raining.

flats and mechanicals

Burton

Cons: The bike needs more frequent maintenaince (some of it expensive), and overall probably has a reduced life expectancy. And sometimes, due to some of the conditions I had to drive in - it looks like ****!

Pros: The rider requires less frequent maintenaince, and overall (barring accident or acts of road rage) has a greater life expectancy. Cycling clothes and a workshop are more fun than business suits and a boardroom.

EKW in DC

Wait. There are cons to commuting by bike? ;-)

Pros:
Cheaper than metro, faster too
Don't have to pay for or worry about parking near my office, cheaper too (and sometimes faster than driving would be)
Exercise and fitness
Good views of the city and the river
Fun

Cons:
Extra laundry
Sweat in summer (though to be fair, that's an issue around here as soon as you step out the door, regardless of activity)

GrouchoWretch

Pros:

1. Sometimes I like to drive up onto the sidewalk, and my car will barely fit. The bike is a champ at this.
2. I have never fallen asleep at the wheel of a bike.
3. Downhills are like riding a motorcycle but without that noise.
4. Nobody runs up and demands money when you park a bike.
5. Bikes are fueled by fat, of which I possess a surplus, and if I run out, I can just eat more donuts.

Cons:

1. Uphills hurt my delicate leg muscles.
2. Sometimes exercise makes me feel like puking.
3. I'm afraid a motorist will kill me.
4. I'm afraid that people will think I'm into "fitness."
5. The City says bikes are exactly like cars, and then they build roads that you'd have to be clinically insane to try cycling on.

RubeRad

I'm jealous! I do have the same sweet setup where I can shower at work, have a locker, and can roll my bike right into my cube. (I can add the cost benefit of letting work pay for the hot water for my showers..., although surely that pales in comparison to gas!)

But my commute is under 6 mi each way, I've only been doing it for 2 weeks, and just like you, "I'm still pretty slow. Typically takes me 35 minutes. I'd like to get it well under 30."!!! If I could do 9 miles at avg 18mph or better, I'd be mighty impressed with myself! OTOH, I do have some hills and traffic to deal with, not a gorgeous constant-elevation riverside MUP. My record time yesterday morning was 30:15 to work (could have cracked 30 if it wasn't for obeying stoplights!), but it's mostly downhill home, and I get in the mid-20's every day.

WPeabody 

Pros: Triking maintains my sanity because I hate driving, gets me outside of my little bubble of self-pity some days, and I meet people. The trike is a great conversation starter. Plus I'm getting in better shape than I did even when I ran cross-country in high school. And I'm finally shedding all those annoying pounds without starving myself. The physical and sometimes mental challenges build character, helps me develop a better attitude toward life, and I'm gaining a sort of zenlike toughness that doesn't let much get to me, like it used to do. Kind of like what happens when you've been on the internet for 20 years. You grow a thicker skin.

Cons: I've been thinking of the inconveniences, the dangers, those days of strained ligaments, uncomfortable weather or illness, but that's all part of forgoing the the habitual use of a private vehicle. You can adjust to that, if you wanted to. I'd say a car is essential for necessary use, like emergencies, going on trips and carrying something that weighs more than 100 lbs...

GrouchoWretch

I barely crack 20 mph average in my car commute, even if I take the freeway for part of it.

noglider 

Funny how the car has trouble reaching its potential more than the bike does. It's 60 minutes by bike and 30 minutes by car. But I thought a car can go much faster than twice as fast as a bike!

Bikeforumuser0017

pros: Exercise, free (not including bike or maintenance), very cheap maintenance, look cool (must have drop bars and skinny tires) lol, less tickets, going between cars, VERY broad price range to fit anyone's budget, the more you ride the better the engine (you) gets (opposite for cars LOL), saves money.

cons: Risking life every time you commute, you may not be up to par with fitness, bike/ parts can be stolen (which happens A LOT), jackass bike haters, takes longer to get from point A to point B.

Mumonkan

pros:
i get to ride my bike even when its a work/school day
it wakes me up in the morning, and puts me to sleep at night
saving money on gas every month
ride most of the time takes less time than i would via car due to rushour traffic

cons:
having to bring a change of clothes
money saved on gas goes to bike parts i dont really need (lol)
sometimes coming home is a real drag after a rough day
rain. (dont have rain gear yet)

BassNotBass

+1. Seriously... people think there are cons?

SPECELIZEDRIDER

downside Not as fast or convenient as a car
upside I save so much money!
I am healthyer
I save in medical costs.