For some expats in Beijing, biking through the streets of Beijing is their favorite way to see the city. You can leisurely cycle from sight to sight, stop for a local lunch, explore old alleys (hutongs) and become one with the Chinese in the bike lane. People chat as they cycle, carry oversize loads and you'll even see arm-powered cycle wheelchairs. Traffic jams will have little effect on the bicycles.
Biking is not just a way to get from one place to another but also an eye into the minds of local people. Cycling in Beijing you sense the mood of those with who you share the road. At times cycling is relaxing and you feel Zen, other times you might feel like you are playing a video game. In general its entertaining, humorous and a great way to explore the nooks and crannies of Beijing and possibly meet some local people.
Roads all accommodate bikes - or maybe one should say they accommodate cars in addition to the bikes. Most people in China cannot afford a car (and imagine the traffic jams if they could). So a bike is their personal mode of transport - and part of Chinese culture.
Don't try and bike fast. The pace of traffic is a leisurely slow and keeps you from sweating or getting in accidents with pedestrians, cars, holes in the road and other bikes. Do not assume someone is going to get out of your way - they may be assuming the same about you.
Renting a bike in Beijing is very easy (although it is easy in tourist spots). A reasonable rent would be 10 to 20 kuai a day but you may have to pay more. You will likely have to leave a cash deposit as well. Ask at your hotel or corner shops. You can also try renting at places where bikes are sold. Someone may even offer to rent you their own bike.
If renting proves difficult or you are staying for a while, you can buy a bike. Bikes cost between RMB 200 for inexpensive ones to RMB 500 or more for the nice, big, heavy and indestructible Flying Pigeons models. However inexpensive mountain bikes with lots of gears are gaining popularity. Gears are not that important though as Beijing is flat and easy to cycle.
If your bike gets a flat tire or the pedal falls off, fear not as you are probably within a short distance of a bike repairman stationed at the side of the road. There is usually a sign and parts of bikes such as tire tubes hanging from it. Fixing a flat or mechanical problem should be inexpensive - under five RMB