Wow this is a helpful thread so now do any of you use the crank based 4iiii. My thinking is I am a shimano person and have 6800 groupset which is prefect in shifting but I am a bike mechanic so I know what to do. I was juct thinking the whole 6800 crankset for a double sided output is $999 that is more than double. Power meter City has the 6800 left crank for $300. Some one give me a thought on what they use or if I am going up the tree correct?