The first consideration in the purchase of a bike rack should be the number of bikes you'll need to carry. Racks come in a range of sizes and shapes. Common sizes may be designed to carry as few as one bike, or as many as four. Consider how many bikes you will need your rack to hold, keeping in mind the possibility of adding more bikes in the future. Also keep in mind that if one rack is not enough to hold all of your bicycles, you might be able to equip your vehicle with two.
Next, you will want to think about where you want your bike rack attached to your vehicle. It can be mounted on the roof, attached to the trunk or rear door, or mounted on a trailer hitch. Where you put your rack is an important consideration.
Bike racks on the roof have the benefit of being out of the way. You won't have to worry about the bikes getting in your line of vision or blocking access to the trunk. The downsides to a roof mounted rack are that they often need to be professionally installed, and that bikes on the rack are harder to stow and retrieve.
Trunk or rear mounted bike racks are easier to use, and can be relatively inexpensive. You can buy one at a bike store, or at stores like Target, Walmart, and K-Mart. They are easy to attach with straps and hooks to your car, so they can be removed when not in use. The negatives to a trunk mounted rack include difficulty accessing the trunk or rear of the vehicle and a less durable construction. Because they rely on fabric straps and less sturdy metal and plastic pieces than permanent bike racks, they are more susceptible to damage and theft.
A bike rack attached to the trailer hitch will likely be sturdy metal construction, and can often hold up to four bicycles. Of course, your vehicle needs to have a trailer hitch in order to use one of these, and while the rack is in use, you will be unable to haul a trailer. These types of racks tend to be quite solid, which is good for durability, but makes them more difficult to attach, detach, and store when not in use.
As with all purchases, you'll want to shop around for the best price and see if your dealer offers package deals, mounting instruction, or product warranties. Adding a bike rack to your vehicle is a fantastic way to bring your bikes with you wherever you go. Find the right product, attach your bicycles securely, and head out onto the open road. Just don't forget to avoid low bridges, and be extra careful when backing up.