Quote Originally Posted by Ana View Post
My LBS told me to stay within a 2cm range from the stock stem because of the changing the position over the bottom bracket. They also said if the stem was too long or too short, the handling might get weird and that may mean you need another size top tube. Keep in mind that they know I am not a super dedicated racer. Maybe the professional riders have longer stems with shorter top tubes which adjusts the geometry of the bike for really fast racing Maybe you have to be more hard core to have a smaller bike and a longer stem? I really don't know I'm not a serious cyclist yet or a racer so my fit is rather average I'm still tweaking my fit I like to enjoy my ride...not too competitive
First of all, I'm not challenging that everyone says your stem should be between 80-120 -- everyone says it. Any bike shop you go into, any online guide to fitting, you name it. And handling is usually cited as a main reason. But to clarify my question (hopefully):

--Position over the bottom bracket is much more affected by seat position/setback than stem length, although a too-long reach could cause you to scootch forward... but again, reach is a combination of stem & top tube length, so a 52 cm top tube and a 140mm stem gives the same reach as a 56 cm top tube and a 100mm stem -- so even though there's a 4cm difference in stem length, all other things equal, the position on the bike would be the same -- the longer stem by itself (assuming the reach is the same) would not cause problems regarding your positioning relative to the bottom bracket.
--But what I don't get is that it IS suggested that you purchase a frame in a size that permits you to acheive your proper reach with a stem between 80mm-120mm, because otherwise the handling will be "bad". But if the handling were really that sub-optimal with a longer stem, would we really see so many pro's on 140s?
--Getting back to your response, It's definitely true that the guys with super long stems ARE riding smaller frames (they're not riding with vastly longer reach). Certainly one reason why pros ride smaller frames with longer stems is because a smaller frame is going to be shorter (head tube closer to the ground), permitting (with a long seatpost) a more extreme position -- but even so, if the handling were really that bad I don't think we'd see those long stems... so???
--When I had my fitting on my new bike the fitter said he didn't love to put people with smaller frames at the larger end of the 80-120mm range, nor people with larger frames at the shorter end (I'm kinda heading towards one extreme, at least by this definition, on a bike with a 51.5cm tt and a 110 stem). I suppose this is partly just because it means you're at the edge of your range of adjustability, which isn't really an issue for pros, but it still seems like there's a sacrosanct rule that bike fitters don't want to put you on stems outside of "the range" -- but if the handling consequences were so awful, why would you see it so often in pro riders? (I should add, after perusing lots of Cycling News features, I haven't seen any stems on male pro bikes shorter than 90mm -- but lots over 120).