I bought a new pair of mavic es ksyriums from the LBS last week. Have put in several good rides including the Talimena skyline in southeast Oklahoma, one of the best kept secrets in road biking (very very hilly). I like them a lot but I have noticed that they are very loud (clicking) when freewheeling. Could this be a sign of a defective product? I know some wheels are fairly loud, but these seem too loud.

Thanks for any input.

The noise of a cassette hub is mostly dependent on whether there is grease or lightweight oil in the mechanism. A little grease in there will quiet things right down. There's most likely nothing wrong with your wheel.