Don't you have some kind of antitrust laws for merges like this? I am by no means expert in U.S. laws, but it seems that Performancebike after the merge with Supergo/Nashbar may have 'significant importance' in the market, which in turns requires special permission for the merge.
We used to. The laws are still on the books, but the lawyers have become very good at identifying the weak spots in the laws.
Even if anti-trust legislation was still strong, you would have to get a MUCH less diversified market. You would have to see Supergo wiping out half the LBSs in the nation to trigger this.
There are still PLENTY of other online stores out there like Cambria Bike Outfitters, Pricepoint, Alfred E. Bike, etc...