Actual heart rate vs Adverse weather conditions

As my training sessions start to change, I have become aware of different techniques of riding my bicycle to get the correct results for the sessions.
I know that, riding with a high cadence (the number of times my pedals do a complete cycle in a minute) I save energy, because it is more efficient. I like this because the higher my cadence the faster my body is moving, which I believe will help me on my motocross bike.
However, to keep my HR (heart rate) high, for a longer period of time, I find it easier to use the top ring on my front gears. This increases the wattage (harder to pedal) and bumps up my HR, although my body is moving slower, my legs are getting stronger.
My conclusion is that, so long as my HR is in the correct zone, either way is just as effective!

Something else that I have noticed is that, at this time of year, my cycle route, which heads South,East,North, then West has a head wind all the way around the circuit. This is great, the stronger the head wind, the more effort is required and it becomes easier for me to hit my HR target and the last thing I think about is cadence!
Likewise, if it is cold or raining, my motivation for working well is to keep warm!