Originally Posted by
Campag4life
Your last sentence query as to why...portends to pros and better amateurs that deliberately size down for a shorter bike which results in a longer stem. You need not make your example so extreme to denigrate a smaller frame and longer stem commonly used in racing. A rider can size down 1 frame size to ride a bike that more matches their short inseam and use a longer stem to match their long torso. No need is the point to ride a bigger and heavier frame with short stem they may even struggle with to achieve an aggressive riding position with short inseam.
It isn't my example, it's Bruce's example. His 6' friend, who would normally ride a 58cm frame, is riding a 54 - which is two sizes smaller. And we know his friend's proportions, so we know that the 58cm frame's TT would be slightly short for his torso length, which means we can assume that even on the 58 he would be using a longer than stock stem.
So the comparison that Bruce proposed is two frame sizes + additional stem length. I'm not the extreme one - Bruce's friend is.