The most important thing is to get a bike that fits you. That is unlikely with a Wal-Mart bike. Not that it can't be done, just unlikely the person on the sales floor knows how to get you properly fitted. Next stop, the local bike shop. I would recommend buying a bike there. The shop's personel will fit you properly. A good entry level bike can be had for about $300. A fall back, if that is out of the budget, is to use the sizing info learned at the bike shop to cruise Craig's List for a cheaper high quality alternative. To settle any ethical misgivings you might have about "using" the bike shop's info but not buying the bike from them, go back to the shop, and buy all the little things you need to ride. Cycling gloves, helmet, maybe some cycling shorts, water bottles etc. They make more profit on that stuff anyway. As well, you could have them tune up the bike which is $40 or $50 dollars well spent.
Last edited by tom cotter; 10-01-13 at 09:00 AM.