Sure, I could use a nice riser handlebar - Enter

Really appreciate all the thoughtful inputs. Guess I'll just have to do some more research before I make up my mind.

Thanks for the help. Competitive Cyclist indicates a TT length of 624 mm so I guess a 17.5" would work with a 10cm stem. That would put me about 1" too short or more upright which is what I'm looking for. Pretty good reference there - thanks for the link! I see carbonazza just posted that he went with a 19" and he is also 5'10". I see that it sucks to be so in-between sizes. let me know if you think my logic is flawed.

All my road bikes are either 56s or 57s and all have about the same reach @ 56 cm with a 10 cm stem. And they're all horizontal top tubes. I guess the problem I'm having is that these carbon frames have such dropped top tubes that I can't relate the frame dimensions to my standard reach. I'm of normal proportions @ 5'9" with a 31" inseam if that helps any.

Great to find a web site devoted to Chinese carbon fiber frames with knowledgeable members. I'm new to riding anything carbon fiber as I've been a steel guy for like forever. I normally ride a 56/57 cm road frame with a 56 cm top tube and a 10 cm stem. So now I'm wondering if a 17.5 will fit better than a 19 29er frame. I recently fell into a new job where I ride the Mickelson Trail (a rails-to-trails conversion) here in the Black Hills of South Dakota. The job requires me to ride various sections of the trail 5 days/week to ensure trail users are safe, following trail rules/etiquette and pay the trail user fees. So I get anywhere from 130 to 150 miles riding in/week. I have been riding a cyclocross bike, but for the amount of time I'm on the bike, the riding position is a little too race oriented. I've been riding on 32 mm knobbies but a wider tire would add greater comfort. So a slightly more upright position and wider tires as well as a considerably lighter bike is what I'm shooting for. I've been looking at zgr9's frame: http://www.ebay.com/itm/Full-Carbon-Matt-29er-Mountain-Bike-Frame-19-BSA-Fork-Seatpost-Headset-Hanger-/171398898441?pt=US_Bicycles_Frames&hash=item27e82ba309
with a solid fork which looks like it would weigh in around 17lbs. So I'm open for suggestions from you all as to whether a 17.7 or a 19 would be the better fit. And BTW, feel free to come up to SD and ride the Mickelson Trail. Its been identified as one of the best!