I'm not sure if your problem is related to food, but when I first started riding I had a really hard time eating anything during my rides because I'd get terrible gut aches. I never had that problem eating gels etc. while xc skiing, so I assume it has to do with the crunched over position on the bike.

All I can say is that it seemed to get better the more I rode, and eventually my body got somewhat used to it. Though I still sometimes get it once in awhile.

I love bib shorts, by the way. I hate to have anything constricting on the belly