how short a stem is too short?

[VeloVT]

I am now curious as to exactly where the "80-120" rule came from. Cycling News has a running feature on pro bikes (in which they obsessively detail the componentry and measurements of a given pro's bike, as well as giving the rider's height and weight). A very large number of pro's seem to run stems between 120 -- 140... and not all of the 130s & 140s are being run by big guys on big frames either. Interesting...

[Ana]

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

[madscot13]

I think racers are willing to bend more for an aerodynamic position that gets them down low, and that often requires a longer stem.

[VeloVT]

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).

[Ana]

Let's keep in mind that men tend to have longer torsos and shorter inseams by proportion compared to women. So maybe by comparison, their reach tends to be longer than women's. Plus, in general most women are smaller than men (although the average height for men is shrinking....the Europeans are getting taller and Americans are getting shorter....on average).

Also, sometimes I feel like those slimy business people will make anything someone might buy just to make a buck So even if it's not advisable (or practical), they will make the product as long as they have customers :P We see this all the time on infomercials :P

Ooo, maybe you could ask a fitter that question....or someone who is serious enough about cycling that they have that weird stem/top tube thingy going on

[OakLeaf]

Do the pros run shorter stems on their crit bikes than on the road race bikes?

Do they tend to body steer more than they countersteer with the handlebars?

Do pros who understand countersteering use their handlebars differently from us mere mortals, especially ones who have never raced bicycles or ridden motorcycles, who may be more inclined to turn the handlebars in the direction we want to go? Or who may be riding at speeds where countersteering isn't even effective?

[VeloVT]

Let's keep in mind that men tend to have longer torsos and shorter inseams by proportion compared to women. So maybe by comparison, their reach tends to be longer than women's. Plus, in general most women are smaller than men (although the average height for men is shrinking....the Europeans are getting taller and Americans are getting shorter....on average).

The difference in relative body dimensions isn't what I'm getting at -- it's not really relevant to the question I'm asking. Pros have access to just about everything they could want (pro teams are how bike companies do R&D). They are not running super long stems because they can't get bikes that would fit them with a shorter stem -- for some reason they are electing to ride small bikes with long stems instead of medium bikes with medium stems (or whatever the equivalent of that equation is based on how tall they actually are).

Us ordinary mortals tend to be advised that longer stems will cause adverse changes in handling -- so we are advised to go medium frame/medium stem -- but since pro riders make their livelihood by riding bikes, I don't think they'd be electing to ride extreme tt/stem combos if, first, there weren't some significant benefit to doing so, and second, if there were adverse handling changes that were at all significant -- they are putting much higher handling demands on their bikes than most of us (high speed winding descents, etc), so I don't think they'd be likely to *settle* on that.

So what's the truth? That's what I want to know . It seems like we get a mixed message from the "conventional wisdom"...



Oakleaf: interesting questions...

[HillSlugger]

So what's the truth? That's what I want to know . It seems like we get a mixed message from the "conventional wisdom"...

Like I said, conventional wisdom is not always true or accurate.

[HillSlugger]

First of all, I'm not challenging that everyone says your stem should be between 80-120 -- everyone says it.

Just because it's said often doesn't make it true. I don't feel I have any steering issues on my bike with the 60mm stem. Having said that, I have to admit that so far I don't feel really stable on aerobars on this bike, but there are lots of other differences between my road bikes, particularly in the height difference between the seat and the bars on the race bike. I'm not sure how that figures in.

[Ana]

--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).

Maybe it's one of those weird penis related things... (i.e. part of those male things that I can't understand...). You know, the "mine is bigger than yours" thing....obviously I have no idea about the long stem thing but I just thought I'd throw that out there