I wanted to start a thread for general tips for commuting. This is for those people who have thought about commuting but have never taken that final step. I'll start by giving my two bits and anyone else can add on with their words of wisdom.
As a die hard commuter and one who lives in some pretty variable weather I have a few suggestions to make. First I want to go over choices for bikes, then I'll touch on gear you will need most definitely and finally I'll go over some tips for riding.
First off, If you are going to commute you need to seriously decide what type of bike you will ride. This will largely depend on what kind of area you are going to be riding in and the distance you will be traveling.
For instance if you are going to be on flat roads that have light traffic then you will want to ride on a road bike. If the area is one with where you will be riding on the sidewalk then go with a mountain bike. If you will be riding in a combined area then go with a nice flat bar bike (I'll explain what a flatbar bike is in a minute.) You'll want to take into consideration the distance of your ride as well. Under 3.5 miles (5 km) then you'll have a pretty lose choice with regards to bikes. If you are going to be riding 15 miles (20 km) or more then you will need a road bike.
With regards to with the road bikes that I've mentioned I'm referring to bikes with a relaxed geometry one that will keep you in an upright position so you can keep your eyes on the road. Many flat bar bikes out there today are great for this, they are a good median between your rugged mountain bike and your sturdy touring speced bike. Flat bar bikes usually have a mountain bike geometry mixed with road bike parts. Most are made of aluminum which many commuters will shy away from. We'll touch on the difference between aluminum and steel in a minute as well. Back to flat bar bikes, I personally ride a flat bar bike made by Marin and I love it.
My ride is 7 miles both ways but I usually will put on extra 10 miles just riding around for exercise or errands. I love the fact that I am in relaxed position but able to sprint out of tight spots when necessary.
People who ride mountain bikes from what I've gathered are those that are riding in very rugged terrain. They are jumping on and off the sidewalk, or running over potholes and other obstacles that will warp a road bike rim. They are often going to be hitting a lot of hills where jumping out of the saddle is more comfortable to add that extra oomph to climbing. Mountain bikes are also tending to be lighter and lighter as well. Many stock bikes weigh in under 30lbs, a far cry from the 80's and 90's and where they seldom broke the 30lb mark. So this is a choice for alot of people who want to be flexible.
Road bikes are the choice of many a die hard commuter. They are often able to set up a great commuter bike weighing less than 21lbs that are able to withstand the rigors of commuting. The bikes are faster than mountain bikes and they less versatile than mountain bikes but they are more efficient overall.
Road bikes break down into three category's with regards to commuting, touring, flatbar and single speed.
Many commuters are turning to the single speed bikes for the simplicity. You will often find that 90% of your ride will be in one gear the whole way. The single speed in my opinion is great for those people who want to avoid dealing with dérailleurs which can become a hassle if you don't know how to adjust them yourself. This simplicity is building a huge following among many commuters.
The flat bar is a road bike with a relaxed geometry and upright position. They are great for urban commuters, those people riding on busy city streets because they allow you to have a better sense of your surroundings while also allowing you to punch out the speed when needed. They are also a great median for those unable to decide between a mountain bike and road bike as well. I'm very happy with my Marin flatbar.
Road bikes that most commuters refer to are either cyclocross or touring bikes. These bikes are strong, often made of steel with a great mix of parts that are ideal for those needing a rugged everyday bike able to handle the rigors of a daily commute. They are a great bike for those wanting something that you can punch down the road and not worry about snapping on the first pot hole. They also have braze-ons for racks which are a plus if you plan on using panniers.
Back to weight, it plays a big part in commuting. It will effect your speed and maneuverability as well as how efficient you are overall. There are many parts that you can reduce weight with and still have a good solid commuter bike. I for one would suggest investing in light seat post, pedals and stem mostly because these parts, even with a reduced weight, are still able to withstand the rigors of your average commute while saving you some lbs/grams in the process.
You will also want to keep in mind what kind of gear you will use for carrying. The choices are backpack, racks, or messenger bags. I'll go over the pros and cons of each. Back pack are great for distributing weight but are not designed for bikes, they tend to slide around on your back and this can effect your control while pedaling. Messenger bags would seem to be a bad choice for alot of bikers but they are not. Due to the sling of a messenger bike it works as a pendulum almost making sure to stay at a centered position which will help you maintain control. Racks and panniers are suggested for any long distance commuters due to the stress that either messenger bags and backpacks can put on your shoulders. You would not believe how much upper body strength you use in biking. Panniers allow you to put the weight on the bike and not your body and also allow for you to carry more as well.
Other gear thats a must is a safety vest, helmet, head light and tail light. The helmet needs to be certified, in US this would be DOT certified elsewhere I would not hazard a guess. Lights should be name brand, and Bright. Tail lights should have multiple modes to work in different types of weather, i.e. flashing, strobe and continuous beam.
Last point I would like to touch on is brakes you will see that bikes these days come with multiple choices, either traditional side pull, cantilever or disc brakes. Most commuters will choose between cantilever or disc brakes.
Both cantilever and disc breaks offer great stopping power, your choice will depend on what kind of weather you will be riding in. The disc breaks aren't affected by weather, which ensures you wont sputter at that red light when its wet out.
I will end this there at that point and hopefully someone adds something to this post.
I also have not gotten around to editing this so point out any errors you might see if you feel it necessary.