There are 123 bike stations around the city (holy smokes!), 3,126 places to put your bike, and 1,560 bicycles. Check out the map below for where each of the 123 bike stations are located:
I live closest to station #27.
There are multiple ways to use BiciMad. If you already have a public transportation pass, you can buy an annual bike pass at a reduced rate. But then you have to pay for each time you use a bike. If you are a visitor/tourist in Madrid, you can buy a cheaper pass for 1, 3 or 5 days.
So far the system has been very popular with the madrilenos. The first week they sold over 3,000 abonos (yearly passes). In comparison, Barcelona only sold around 1,000 in the first month.
Here's the Madrid becoming greener!!!
Check out more info here (in Spanish) if you want. Photo credit for the map also from this site: BiciMad Official Site