The asymmetrical design of the new 105 chain helps the chain shift more quickly to the large chainring as well as provide a faster upshift to the larger (easier) cogs on the cassette.
Please note: the 5701 chain is directional like the 7900 and 6700 so it must be installed in the correct orientation
Love these chain. I believe they are the same as Ultegra just that the plates aren't polished and the Ultegra is the same as Dura Ace just without the hollow pins (those pins lighten your wallet way more than your bike). I have wasted my money on the Dura Ace and Ultegra compared them, including weights, and wouldn't waste my money again.
Pros: Just as good as Dura Ace/Ultegra