About Mavic Ksyrium ES: The ES asserts itself as more of a climbing wheelset: First is the lower-profile depth of the front rim. The front rim on the ES is only 22mm deep. This makes it a lighter wheel and it has the incidental advantage of making it a more stable wheel in cross winds and at high speeds on descents (after all, if you're using these in the mountains, you have to go down, too!) The rear wheel on the ES is still 25mm. The reasoning behind this is that it gives the rear wheel added rigidity and resistance to flex, which according to Mavic gives it superior power transfer. The second way in which the ES is designed with climbing in mind is its generous use of titanium: The skewers are made from Ti, the rear axle is a Ti/aluminum mix, and the freehub body is supremely lightweight -- the Shimano freehub body is made from Ti, while the Campy one has to be made from aluminum alloy since its Campy-specific splines are so deep. Note, too, the newly designed oversized carbon fiber front hub. The oversized shape of the ES is designed to shave a few extra grams from the total weight of the wheels. Limited Time Special Offer: Buy any Mavic, Zipp or Ritchey WCS Carbon Wheelset and get a Dura-Ace 10-speed chain FREE. Here's how it works: Add any Zipp, Ritchey WCS Carbon wheelset or select Mavic wheelsto your cart. Next, add a Dura-Ace chain (item code CMR-CHA-CN7801) to your cart. Use Coupon Code FRDAC when you check out, and the cost of the chain will be deducted from your total. Note to Campy and SRAM fans: you may substitute another chain. Call for a credit equal to the cost of a Dura-Ace chain ($35.99) towards your purchase.