Originally Posted by
bruce19
Guess we will have to disagree. If as you say there are variables that affect the use of inseam as a determinant I'd guess those variables exist using height as well. So, I don't see height as being better than inseam.
I don't see how you'd come to that conclusion. Frame size is like dress size - it is an overall size that attempts to cover both seat height and reach. You're suggesting that it is better to size something like that by only paying attention to one isolated part of the anatomy rather than the larger picture. Women don't size dresses by only looking at leg length, and I don't see why you'd size a bike that way. The "traditional" sizing advice wouldn't be used if someone fails to have a "traditional" build.
It would be interesting to see a picture of your 6' tall friend with the long torso crammed onto his 54. Does he have a 170mm stem?