I changed my 58t chainring back to the 54t for yesterday's ride, and I found that for the tailwind section where I gave it the beans on the tailwind section my cadence was much higher than what I've grown accustomed to with the 58t. It was surely in combination with the +30C heat but that higher cadence felt like it was really taxing me. I never use a HRM but I certainly felt my HR in the red zone. I had a feeling all of that was going to happen by dropping to the 54t but now I know for sure.