I have a Shimano Ultegra FD-6700 derailleur...
I have a Shimano Ultegra FD-6700 derailleur setup on my bike with a 53x39 SG-X crank. Can I run the 11x28 with this and if so, do I need to change my chain length? Thanks.
Yes, 11-28 will work well with your described kit. However, FD does not impact chain length. More importantly, what is the size of your largest sprocket in your current cassette? If it is anything other than 28, you may need to adjust your chain.