Decathlon
Decathlon is the ‘go to’ store for outdoor and sports gear in Bucharest. Excitingly, they have just opened their largest (and most anticipated) store in Baneasa (opposite Baneasa Mall and Ikea). They stock all the winter gear you might ever need, and all the summer sports and splash gear too. Their stores are always large and have lots of space for equipment sales too, including tents, home gym, bikes (if you purchase a bike, they will set it up for you instore).
You can browse the full catalogue and place orders online (for home delivery or Click and Collect).
Website: http://www.decathlon.ro/ and 
https://www.facebook.com/Decathlon-Baneasa
Address (Militari): Militari Shopping, Bd-ul. Iuliu Maniu nr. 546-560
Phone (Militari): 021 408 50 00
Address (Baneasa): Soseaua Bucuresti – Ploiesti, nr. 83-85-87,
Phone (Baneasa): 0372.273.641
Need new sneakers for the kids? This is the place. Also, all sports equipment, bikes and tents in the summertime, exercise mats, backpacks — if you need it for something athletic or outdoors, this is the most likely place to have it in Bucharest.
We love Decathlon and go there with kids with pleasure, because they always find a bike to ride around, while we are searching for clothes or boots. Very good quality and inexpensive sport shoes for kids.
Free bicycle rides and always balls around. A nice place to buy clothes and to play at the same time. My boy loves it.