Ah ha! This isn’t the question you thought it’d be...

Bought some new cycling shoes and they are about 5 ounces heavier per shoe. The fist time I rode with them was for about 32 miles. I noticed I was a bit more tired than normal, and my leg muscles were kinda sore. I just chalked it to not being out riding as much lately due to the weather. Yesterday, I put in 51 miles at a place that is relatively flat, somewhere I go where I can gauge exactly where I stand physically and put some really good speed. After about mile 35, I was dragging tail. Legs were absolutely burning the last 10 miles. Speed dropped off about .7 mph the last 15 miles. That hardly has ever happened to me there.

So... my question is, can shoes that are only 5 oz. heavier than what you’re used to have that kind of affect, or is it probably something else?