Are you sure your min/max heart rates are set correctly!? I don't think I'm ever in zone 0 unless I'm on the couch. Even light warmups put me in zone 1. Your riding pace is pretty fast so I'm shocked you don't get more.
For reference, Garmin has my zone 1 at 98-116.
Well yeah there's a lot of mixed info on what they should be set to eh. But I set mine in accordance to a document Brent had emailed to the HPP about the zones they wanted athletes to log.
1 - 65-76
2 - 76-85
3 - 85-90
4 - 90-95
5 - 95+
But yeah it means I have to work reasonably hard just to get my zone 1 on (127 to 148 bpm for me). Or maybe I'm just super fit :p
Also my biking is limited by the power in my thighs, I'm very rarely out of breath but I can't push much harder because my thighs are just on fire