I'm considering bidding on ebay for a lemond poprad cantilever 57cm. I am probably 5' 10" with a 30-32" inseam. I read the other thread about this but didn't find a specific answer. Just thought I should ask before bidding. Cheers.
According to the plot, I would size you at 54cm. There're a few other members with your measurements (70" tall, 32" inseam) and they are on 54-56cm frames. Cynikal for instance also has a Lemond Poprad and takes a 54cm. So 57cm may be a touch tall, but I think it's a really close call. I would check to see that the standover height is sufficient (it'll be close!) for your riding style.