A buddy is swapping his 10speed Dura Ace crankset for somthing else and has offered it to me cheap. I currently have a 10 speed Ultegra crankset. Will the DA crank bolt right on? Does the bottom bracket need to be swapped as well. Also, how is a crank arm measured? I'm assuming it is from center of the crank axel to center point of the threaded hole where the pedals are mounted. Thanks in advance.