Biking to your destination is different than driving there. Plan your bike commute around your usual route, but seek out quieter roads and avoid the major ones. Ride on roads that you feel comfortable on. I would avoid very busy or narrow roads so that there is enough space between you and the cars. I also avoid intersections which are “dangerous”, such as when there are angle streets intersecting with other busy streets. For my 20 mile commutes to and from work, I know of several routes. They are mainly on roads which parallel busier roads, or shortcuts through residential neighborhoods. In the city, busier roads can be hectic, but once you understand the flow of traffic and other bicyclists sharing the lane with you, then it is not so bad.
You can drive the route you want to take to familiarize yourself, but there is no substitute for actually biking the route. I suggest biking the route at a less busy time so that you can understand the traffic flow and judge how much spacing you have between yourself and cars. If you don’t have the time to bike the route before you commute for real, just take your time when you first try it out. As an alternative, “drive” the route by using Google Maps, but don’t depend on Google Maps to tell you which route is safe by clicking on the bicycle route option and seeing roads appear in green. Most of the time it is ok, but you really don’t know. I once trusted a route Google Maps suggested, but it turned out that during rush hour, cars didn’t want to give me space. The same road at 6am is safe to bike on, but in the evening rush hour it is not. Bike paths are OK if you are not going very fast or want a more leisurely ride, but you will find that quieter roads will allow you to travel more quickly.
You will want to consider the conditions of the roads. You’ll want to watch out for cracks and bumps in the pavement. Wider roads will allow you to have more space between you and the cars and I avoid narrow roads unless the speed limit is very low or with speed bumps. Also pay attention to when construction on roads will happen, as you’ll need to plan for an alternative route.
If you live far from work, don’t feel like you have to bicycle the whole way. I live 20 miles away from work and found that a bike-train-bike mode of transport is great.
Go ahead and use public transportation to break up the route and bypass roads. The CTA and Metra have restrictions on bikes based on the time of day and which way you are traveling, so check their websites before you decide to bring your bike.
Once you become more fit, you may realize that you can eventually bike the whole distance and save yourself some cash.
By knowing your main route along with other alternative routes, you can be flexible and handle any unexpected situation. Finding a safe route makes your commute easier by minimizing stress so that you can fully enjoy your ride. Once you are comfortable with your route you can use that knowledge to your advantage. For instance, on hot summer days, I know which route can offer me the best shade. I also remember certain houses which have their sprinklers go off near the street so that I can ride through the spray and be momentarily cooled.
Once you get your route down, the amount of time it takes you to bike commute will be fairly consistent. Don’t listen to people who say they can ride xx distance in xx time. You could be faster or slower, depending on the traffic and how hard you want to ride. Also, bike commuting is not a race. Take your time, follow the traffic rules, and BE SAFE!