Join Date: Jul 2005
Location: St. Paul, MN
Bikes: Cannondale CAAD9, Ritchey Breakaway Cross, Nashbar X-frame bike.
deraltekluge and trace beat me to the geometry discussion, so I won't get into great detail.
The measurement you are referring to is the seat tube measurement. It's the length of the seat tube from bottom bracket (where your crank is) to the top of the tube. (Or the center of where seat tube and top tube join. But that's another discussion in measurement methodology.)
Is there a correllation?
Aside from the 2.54 conversion factor, there is very little unless you are comparing bicycles of similar geometry. For instance, for a guy of my size, a bike with "mountain bike" geometry in approx a 16 inch frame is appropriate. However, 16 inches with "road" geometry would be ridiculous, and the bike simply wouldn't fit. In a road bike I ride a 50cm frame, which is closer to 19.7 inches.
Many factors influence this, from intended posture of the rider, to bottom bracket height above the ground. Bike fit is a complex "problem" and done wrong can impact your efficiency at best...your ride comfort and enjoyment at worst.
If you're in Salt Lake, where to go depends on your budget. Contender Bicycles on Ninth and Ninth is very good. Bingham Cyclery has locations all around the Wasatch front, and they have a great reputation, and I've shopped there often. Canyon Sports in the summer months caters to cyclists, and they have an affordable lineup of Raleighs...and they usually have great sales as the ski season approaches. I forget the name of the shop on Broadway (3rd south) in Salt Lake...but they had a nice operation that had a good reputation.
Good night...and good luck