I replaced my whole crankset with a 5800 compact. Rest of the drive train is 6750. Works great, have about 4500 miles on it now. I found it online for about $90 as I recall. New chainrings alone were going to cost me $70. A friend of mine had the shaft shear off on his crankset, his bike is 7 or 8 years old and probably had 35000 miles on it. So well worth the extra $20 or so to replace the whole thing.