You can get a simple exercise bike that lets you pedal away. It may offer you various tension settings and perhaps an odometer. You may find many of the older models have this, and this is all you really need to get a good workout. Some new versions of exercise bike come with a digital readout that will tell you how far you have gone and even might help you determine how many calories you have burned or what your heart rate might be. These can be useful if you have gotten specific instructions from your doctor on getting your heart rate up to a certain point.
If you dont want something fancy in an exercise bike, you might ask around to see if someone in your family has one you can use. You may be surprised to find that many of your relatives have an exercise bike hidden away that they once hoped to use on a daily basis. They may be sheepish when they admit they have one, but they may very well be happy to see it being put to good use. Remember that once you have the exercise bike in your hands that they best thing you can do for yourself is use it. Even if you dont know to lose weight, this type of exercise is great to get you in a good mood and to relieve stress.