Yes and you'll need to take a few things into consideration before setting up your bike to be stationary. First, to ride your bike inside you will have to raise the rear tire and stabalize the bike. You will also have to provide resistance to the tire and lift the front tire to level off your bike. If you are on a budget, you could use something around the house to raise the front tire but I highly recommend using a riser or stabilizer block which is specifically made for converting a bike for indoor use.
Second, you need some kind of resistance, extra stabilization, levels of difficulty, sweat protection, progress monitoring and tools. Some of these things are optional or can be added down the road. If you are on a budget, start simple and add more options later. Below we go in to more detail of each of these options.
Resistance: The budget models require you to get off the bike and manually change the desired resistance. The more expensive models will either automatically change or you can run a cable to your handle bars in order to change the resistance while riding (remote). Progressive resistance is also available on some models which provide increased resistance as you increase speed. Some units replicate the feel of the open road while others have frames that can move and rock from side-to-side providing more realistic riding.
Comfort: Riding in your pok-a-dot PJ's may not be as comfortable as they are lounging around the house. Consider jerseys, shorts and gloves made specifically for biking,
Climbing Blocks: Blocks stabilize your bike while also providing different levels of difficulty. Most blocks are adjustable or you can stack blocks together.
Riser Rings: Riser Rings are similar to climbing blocks.
Floor Mat: A floor mat will protect your floor from getting scratched, absorbs noise and vibration. It also helps prevent your converted indoor bike moving around while riding. Mats can also be used to keep sweat off the floor.
Handle Bar Holder: No need to steer when inside. This will help keep the bike stabilized while riding or moving the bike around.
Sweat Net: When you are bent over your bike sweating... it drips. A Sweat Net protects your bike and floor. Also called a Bike Thong. Sweat can be corrosive to bike parts and floors.
Bike Computer: Track your progress, mileage and speed. Some models will even track your hear rate and calculate calories burned. Other features can include max speed, average speed, trip distance, 2nd trip distance, total distance, elapsed time, clock, total pedal revolution, etc.
Seat: Seat covers are a great way to make your bike more comfortable without having to replace your seat. Remember that you do not need a weather proof seat cover. So your options are wide open.
Apparel: Biking shorts can have a padded crotch for added comfort and easily streach with your movements. Gloves can provide great shock absorbency. Biking jerseys can help prevent sweaty chills during cool-downs.
Tools: An all on one tool is perfect for anytime fixes that may be needed. A bike pump is still needed to your tires properly inflated, even with a converted indoor stationary bike.
Cleaning: Keep your area clean. Keep a dry cloth handy to wipe soiled areas. As with any bike, keep your chain, derailleur, freewheel cogs, and chainrings clean (see Chain Gang Chain Cleaning System).
Safety: Until you test out the stability of your new converted indoor bike, make sure breakable items are not in range of a tip over.
Pros: Converting your outdoor bike to an indoor stationary bike allows you to use your bike year round. Save on the cost of a permanent indoor bike or excersize systems. Store it away during the warmer season while your are using your bike outdoors. Watch TV while riding.
Cons: The cost of some of the high-end systems can be expensive. Takes up space in your house or apartment.