thanks for advice!
I'll try to find something that attaches to seat post. I was buying used, so I only have choices of what comes along, that devinci amsterdam looked pretty good, but I ended up getting a Cdale caad8. I used a shoulder bag today, it was a little sweaty, but as my friend pointed out once, you get sweaty anyway so what's the big deal.
I'd still prefer to use my rack mount bag on something though.
thanks again for tips