The ENVE XC, while being the lightest in our mountain line is far from fragile.  With the understanding that what goes down, must come up first, our XC rim is optimized for stiffness, weight, and durability.  The ENVE XC rim is made for cross country racers and trail riders alike, and is only limited by the amount of free time you have to ride them.  In 2011, through an extensive development process, we made the jump to tubeless compatibility completing the requirements for the optimal mountain rim that can be used day in and day out.  So, if the mention of 100K makes you think of riding and not the amount of money you want to make, then this rim is for you.