For the same RPE indoors compared to outdoors, my heart rate seems to be 15-20 bpm lower indoors. I could be maxxed out on my trainer, but top out at 162 bpm on the trainer, whereas I'd be at 180 outside for a similar effort. I'm not taking indoor speed into account here, but rather, RPE. This happens on both my rollers (Travel Trac, no resistance) and my trainer (Cycleops Fluid 2), with the rollers giving me lower HR numbers. Does this happen for some of you? Thoughts?