I find my chest and belly get cold and turn red when I ride in temperatures under 30. My arms, legs, and face are OK. My feet also get cold, but I understand that. This has been going on for a while but most of my rides are 3-5 hours, so I could imagine reasons related to being exposed for such a long time. But yesterday it happened on a 17-mile training ride where my average heart rate was 90% of my maximum and I hit my max on two of the climbs - i.e., I was working really hard. When it happens, it feels like the front of my torso is slightly chilled - I feel like I am on the verge of being cold. Originally I wasn't really sure if it was really cold until I felt my flesh after I got home and stripped.

I'm wearing a medium-weight thermal shirt and pants, a long-sleeve cycling jersey, leg warmers, and bib shorts (plus hat, neck gaiter, gloves, socks & shoes for the extremities). On my colder rides (20 degrees) I've added a PI rain jacket (too hot after 10 miles), my arms sweat. I tried a new LG vest (once - I may return it) but I didn't notice any difference.

Questions:

1. Why didn't the vest make a significant difference? It's a Louis Garneau 2010/11 Men's Vent 2 Cycling Vest. I was quite surprised that it didn't make my torso noticeably warmer, like my jacket did (or maybe it didn't, and I was unknowingly led astray by my arms being warmer).
2. Any observations or suggestions that might help?

This is another case where I am awed by my ignorance. I've backpacked in winter, mountaineered, and run distance throughout many, many winters. It doesn't seem I should need ask these questions, but I've learned you guys (and gals) are good. Thank you!