now that my folder is messed up - righthand brifter is dead - I have to ride my roadie to work. that's normally fine, except I had a lot to carry home today. so I decided to try the seatpost-mounted rack with my topeak bag:
not sure why I expected to have problems, but it worked like a charm. and I was able to average 16.2 vs. a fastest average of 16.6, so I don't think it slowed me down.
now I am less motivated to fix the folder. the thought of riding the road bike every day is quite appealing :-)