Two words: Freaking Awesome! The initial noticable difference is that I can now touch the ground much easier due to the lowering of the front by a couple of inches...19 inch wheel in front to a 17 inch wheel in front. The bike handles fantastically and I highly recommend the swap if you have the means. I picked up the wheels off of an X-challenge owner, so the hubs for the X-challenge are exactly the same as the X-country. The Excel wheels were laced up by Woody's and so far they're a blast to ride on.