Originally Posted by JasonD67

I've been riding for decades, but just recently got a Scosche heart rate monitor. Only ridden with it a 100 miles or so, but found something that really surprised me. When I ride inside on the trainer, my HR is 20-30 beats less than when I ride outside despite me riding just as hard (or so it feels). Inside, I stay in Zone 2 most of the time and have to work to get into Zone 3. Outside, I'm in Zone 3 most of the time and the slightest hill puts me into Zone 4.

Now, the only difference I can see (other than it being a different bike on the trainer) is the temperature. Outside it's been in the 40's (~5C to our more enlightened readers), while my trainer sits in my toasty house. Have others experienced a similar increase in HR in the cold? I guess that might explain why my speed and cadence is lower overall in the winter as my body is using so much more energy to stay warm, as measured by the increased heart rate.