new shoes? check your saddle height
 

I keep learning this lesson over and over, and this morning I got to relearn it. Whenever I buy new shoes it seems like the sole is a different thickness than the old pair, and I end up adjusting the saddle height to compensate for the change.

Are these the same model of shoe or is it when you switch models/brands?

Different brands. But the good news it that I usually get to raise the saddle and become more efficient.

Check your cleat location as well. I don't pedal with toes down all through the stroke, but ankling a bit means the optimum saddle height varies with how far back my cleats are set.