The way I learned to calculate HR zones/percentages was this:

1) Find your max HR ... in my case, about 195 bpm

2) Multiply your max HR by the percentage you are looking for. For example, if I want to ride at 60% of max, I would take 195 bpm and multiply it by 60% to equal 117 bpm.

But I have heard there is another, somewhat more complicated, method of figuring out HR percentages. Anyone know other methods of calculating HR percentages?