The aluminum frames used for lower-end (road) bikes sold by Walmart and equivalent are different from the frames of name-brand road bikes sold in bike stores. One of my commuter bikes is an AMX Patriot (aluminum frame with aero tubing, chro-mo fork, 8-speed Sora w/downtube shifters) that I bought from a pawn shop and was originally sold by Toys-R-Us (!); that bike weighs well north of 30 pounds because it has non-heat-treated tubing with thick walls. Building aluminum frames and skipping the heat-treating step saves the manufacturer a significant amount of time and money.

So that's one way to cheap out on bikes made to be sold in big-box stores. Another is that the bikes are offered in only one frame size up to a surprisingly high price point, even above the point where the lighter, heat-treated frames start showing up. That's another significant cost-cutting technique.

I don't doubt that the lighter-weight road bike frames at big box stores are comparable in quality to the equivalent bikes sold in bike stores. I wouldn't hesitate to buy one of the pricier ones if it happened to fit. And you have to like that no-questions-asked return policy, which is one area where the big-box stores beat the LBSs.

But I voted with my dollars by buying a BD Moto Le Champion SL 5 years ago. Great bike, no complaints.