Best Buy (NYSE:BBY) is rolling these days -- literally.

The leading consumer-electronics chain is starting to sell Segways, Brammo electric motorcycles, and other plug-in bikes at a few West Coast stores.

The big-ticket rides are a logical way to drive sales at its superstores, but the move also threatens to dilute Best Buy's killer brand.

I get what Best Buy is doing. Many retailing giants are starting to invade Best Buy's turf. Wal-Mart (NYSE:WMT) sells iPhones and satellite-radio receivers, and Home Depot (NYSE:HD) is selling HDTVs. So why should Best Buy box itself in?

Well, what's wrong with just gunning for the displaced Circuit City shopper? Best Buy's largest rival liquidated its bricks-and-mortar operations in March, so Best Buy should be able to grow its reach without expanding its store categories.

I had no problem with Best Buy's move to stock up on musical instruments last year. They complement other Best Buy categories, such as CDs and audio systems. Besides, since the company has had folks jamming to Activision Blizzard's (NASDAQ:ATVI) Guitar Hero games on display models in its stores for years, it may as well offer the real thing. But where do you go with eZip electric bicycles and Segway motorized scooters? Do you begin stocking auto parts, or bike shorts?

Best Buy can't simply become a catch-all retailer. It can't become Wal-Mart in blue and yellow. It can't even become Amazon.com (NASDAQ:AMZN), which has evolved from its media retailing roots.

It's too soon for Best Buy to begin abandoning its consumer-electronics stronghold. There are too many smartphones, netbooks, and plasma televisions to sell for the market leader to begin spreading itself too thin.

Why roll when you can still rock? 

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