If you have to juggle stem lengths to make a bike fit, what is the trade-off of using a short stem length. Salesmen told me he didn't like using 80mm or less stem. Couldn't really tell me why. The bike I'm looking at would need at least an 80 to work.

The shorter the stem, the squirrelier (is that a word?) the steering. Much less than 70mm, it can get freaky. That said, I've used a 75mm on my Roubaix to good effect. It took less than an hour to get used to. It is definitely 'livelier' than the 100mm stem it replaced. Now I've got a 90mm on it, but with a steeper angle, and will see how that goes. Hint:Having to use a really short stem like this MAY mean the frame's geometry is not right for you!

If you have to juggle stem lengths to make a bike fit, what is the trade-off of using a short stem length. Salesmen told me he didn't like using 80mm or less stem. Couldn't really tell me why. The bike I'm looking at would need at least an 80 to work.

I may be missing it, but you find a frame that fits. The stem is secondary. If you don't fit the frame and try to compensate with stem length, you won't have a properly fitting bike and won't be happy long-term. Is he trying to sell you a bike where the frame doesn't fit you, and then advising you to adjust the stem size? If so I'd keep shopping. I'd also be suspicious of a salesman that doesn't know the product well enough to describe the effect of the stem on handling and overall bike fit. Any of the guys at my LBS can discuss that ad infinitum. He may be new, but if there's not someone else at that bike shop who is knowledgeable enough to explain all that to you, that is a red flag.

A lot depends on the frame size. It would be "Goofy" to put a 80mm stem on a 59cm frame, likewise, it would be very strange to have a 140mm stem on a 52cm frame.
An 80mm stem might work fine on a 52/53cm frame.

Yah, my wife uses a 80cm on here 48cm Dolce. She was fitted by the LBS owner who fits people well. She might go to a 75mm now as she has not been riding as much.

80cm or small seems like it more for smaller bikes as you mentioned.

The shorter the stem, the squirrelier (is that a word?) the steering. Much less than 70mm, it can get freaky. That said, I've used a 75mm on my Roubaix to good effect. It took less than an hour to get used to. It is definitely 'livelier' than the 100mm stem it replaced. Now I've got a 90mm on it, but with a steeper angle, and will see how that goes. Hint:Having to use a really short stem like this MAY mean the frame's geometry is not right for you!

I swiched from a 10cm to a 8cm stem and did not notice any difference in steering except my reach has improved greatly and I am a happier rider on that bike. However, I ride a size 52 frame so I do not know if it has anything to do with it. A lady friend of mine who rides a size 50 frame with a 60mm stem for as long as I know her and I have not seen her crash yet. Comments like freaky, squirrelier when people talk about shorter stems sound like a load of crap to me. I can see going from one extreme to another like chaning from a 130mm stem to a 60mm might make a difference but 20mm difference in stem lenght does not change the steering much.

Comments like freaky, squirrelier when people talk about shorter stems sound like a load of crap to me. I can see going from one extreme to another like chaning from a 130mm stem to a 60mm might make a difference but 20mm difference in stem lenght does not change the steering much.
I disagree. If you ride much and you like a bike that handles well, a change in stem length is very important. Not only does X amount of steering input move the bars farther, a shorter stem redistributes your weight toward the back wheel, making the bike less confident on descents. The same could be said of a stem that's too long (for different reasons).

I'm one of those guys who could discuss stem length ad infinitum. Go with what pepe said and get a bike that fits right out of the box.

Not only does X amount of steering input move the bars farther, a shorter stem redistributes your weight toward the back wheel,

The steering arm dimension is the distance between the fork steerer and where your hands contact the bars—the stem is just a link in between. Moving your hands from the tops of the bars to the brake hoods lengthens that steering arm by about 150 mm, with little effect on how the steering feels. Longer or shorter stems do not change "steering feel" because they shorten or lengthen the steering arm, but because they shift the rider's weight, as you correctly pointed out.

Have no clue as to what brand of bike you are talking about but I can only relate to this question in terms of the Italian bikes- which mostly my stable is made of. Here's the scoop as I see it....the trail,wheelbase,bb drop,angles and front center are sort of fixed...stem length isn't and your bikes want your weight on its front wheel as much as it wants it on the back...most bicycles even racing bikes are set up with extreme weight bias towards the back...now bikes are wonderful things...but get that rat trap up over 30mph while conering hard or descending a col at 60mph and your going to want that long tiller on your yachts skipper.This goes hand in hand with the Italian way of building bikes...buildem' around front center measurements and balance first...everything else comes later...including but not limited to...a longer stem.

I disagree. If you ride much and you like a bike that handles well, a change in stem length is very important. Not only does X amount of steering input move the bars farther, a shorter stem redistributes your weight toward the back wheel, making the bike less confident on descents. The same could be said of a stem that's too long (for different reasons).

I'm one of those guys who could discuss stem length ad infinitum. Go with what pepe said and get a bike that fits right out of the box.

I know you are the expert and you can disagree all you want but the fact of the matter is that 20mm difference in stem lenght did not change the steering characteristic of my bike by much if not at all. I hit 35 mph down hill every ride around here where we have a lot of rolling hills so maybe it is not fast enough to detect a noticable difference in my stem lenght change.

In regards to a new bike that "fits right out of the box", it does not exist in my book, unless you have a custom frame built and have own a lot of bikes prior to that so you know exactly which setup works for you. I have seen a lot of new riders in our club who are not too pleased with their pro fitting because they are being fit by the book and not by what the rider's riding style. Fitting can be very subjective so a bike that fits a rider perfectly therorectically does not always turn out to be perfect.

The steering arm dimension is the distance between the fork steerer and where your hands contact the bars—the stem is just a link in between. Moving your hands from the tops of the bars to the brake hoods lengthens that steering arm by about 150 mm, with little effect on how the steering feels. Longer or shorter stems do not change "steering feel" because they shorten or lengthen the steering arm, but because they shift the rider's weight, as you correctly pointed out.
I disagree with your contradiction, sir. It doesn't feel weird when you move from the hoods to the top of the bars because a) you know what to expect and b)you're not really steering when you're on top anyway.
When you're on top of the bars, you're only trying to keep the thing straight. Notice next time you ride that it's actually harder to ride in a straight line when you're on the top. You would never try to negotiate a technical road like this. All the slop in your input affects the bar more because you're closer to the steertube. Think of descending a steep hill with your hands on top of the bar. Besides not having brakes, would you attempt it? No, because you need the precision of having a long steering arm. Yes, it makes a difference.

I have seen a lot of new riders in our club who are not too pleased with their pro fitting because they are being fit by the book and not by what the rider's riding style. Fitting can be very subjective so a bike that fits a rider perfectly therorectically does not always turn out to be perfect.

That's correct. Fitting by the book will always never work. My LBS who fit my wife and me both asked ask to ride like we normally do. Then thery adjusted the fit around us. Then asked us to try something differnt to see how it felt. If we felt better then he found a better spot. If not we went back to were we felt right, but were fitted and sitting properly on a road bike.

I have learned much about fitting and my body type/style where I have dialed my self in pretty good were another position will cause discomfort.

For my wife who only road MTB's the fitting was very essential. They fit here close to her MTB position, but at the same time getting her for set-up for a road feel. The compromise at first was slighty uncomfortable for say 10 min on the maiden voyage. After a 1mm adjustment on the fore/aft of here seat, she was feeling great and has never had a complaint about fit. She is sitting properly and feels great. Man setting up a MTB fit is sooo much easier.

Yah, my wife uses a 80cm on here 48cm Dolce.

That's a LONG LONG stem there man!!! :D

Do people still follow the 'I can see the front wheel hub in front/behind my bars' thingy when deciding on stem lengths?

I disagree with your contradiction

I wasn't trying to contradict your basic construct, but rather make the point that the effect of lengthening or shortening your stem has on steering is often overstated. Also, there's another "steering arm" which changes handling. It's the distance from your hands to the steerer measured at right angles to the top tube—in other words, effective bar width. So there's something else complicating things. You're right, of course, on where to grab your bars when things get fast and twisty.

Perhaps obvious, but still interesting is that riding one-handed changes everything. When you ride track and try your hand at the Madison, first thing you learn to keep your bar hand as close to the stem as possible when you launch your partner. It's the only way to keep your line during the launch. Photo top to bottom is Bruno Risi and Erik Zabel during the recent Dortmund, Germany 6-day race, which they won.

Sorry, 48cm Compact. My wife is 5' 1"
Here is the geometry. It works for her. Just giving an exp.

http://specialized.com/OA_MEDIA/2005/bikes/05DolceElite_l.jpg
TT*: 510mm
Standard stem: 75mm
* TT is measured horizontally from center of HT to center of ST

nice bike...

A lot of the advice you've received, although well meant is in error.

I will agree that unless you need a very small frame, then an 80mm stem length means the frame reach is too long. Do you know this for a fact, or is it just based on comparing TT lengths (the wrong way to do it)?

Changing from an 80mm to a 120mm stem only changes the length of the steering arm about 15%, so it will not have a great affect on steering. It will also NOT change the weight balance significantly. Anyone who has done accurate checks of weight balance knows that two things change the weight balance significantly. The first is moving the saddle fore or aft. The second is the angle of your torso. Since serious cornering is always done from the drop position, torso angle won't vary much, regardless of stem length. It's entirely possible to have the same torso position with an 80mm or a 100mm stem. The thing that will change is the bend in the arms. If your stem is too short, you'll have a significant bend in the arms in the drop position, and most likely some arm to knee contact that requires the rider to flare his elbows. I like to use a stem that's just long enough to avoid knee to arm contact while pedaling in the drops. That leaves the saddle fore/aft position as the major contributor to a change in weight balance.

A bike that has too much reach probably has too much front-center and it will be lighter in the front than a bike with less front-center. You'll never notice it unless you do some seriously fast cornering, like on a technical mountain descent or a criterium..

A bike that has too much reach probably has too much front-center and it will be lighter in the front than a bike with less front-center. You'll never notice it unless you do some seriously fast cornering, like on a technical mountain descent or a criterium..


Can you elaborate on this? What is front-center? Is this a bad or a good thing?

Perhaps obvious, but still interesting is that riding one-handed changes everything. When you ride track and try your hand at the Madison, first thing you learn to keep your bar hand as close to the stem as possible when you launch your partner. It's the only way to keep your line during the launch. Photo top to bottom is Bruno Risi and Erik Zabel during the recent Dortmund, Germany 6-day race, which they won.
What's interesting is, one guy there is gripping the top of the bar and one guy is on the drops. As you know, they are exerting equal but opposite forces against each other through the force of the launch. We could analyze the situation, but it's such guesswork I don't think it would resolve the discussion of how drastically stem length affects handling.

Dirt boy: 51cm is the actual TT length of that Dolce; the effective TT - the dimesion Specialized uses for its relevant geometry - is longer. If you have the frame with you, there should be a sizing sticker describing the virtual ST and TT lengths.

Front-center is the distance from the center of the BB to the center of the front axle. TT length, head tube angle and fork offset all affect the front center.

Brands like Colnago tend to have longer front-center dimensions than others, mainly due to slack HTAs, particularly in the small sizes.

As I noted, the only riders likely to notice the effect of difference in the front-center are those who engage in extreme cornering. The average rider won't notice the difference.

I've varied the weight balance on a bike by moving the saddle back as much as 3cm, as an experiment. Even this much shift in the weight toward the rear didn't have a great affect on the ability to corner at high speed, but I do prefer the around 45% of the weight on the front, rather than as little as 40-42%. I feel like the bike negotiates hairpins at 35-40mph better with more weight on the front.

I've varied the weight balance on a bike by moving the saddle back as much as 3cm, as an experiment. Even this much shift in the weight toward the rear didn't have a great affect on the ability to corner at high speed, but I do prefer the around 45% of the weight on the front, rather than as little as 40-42%. I feel like the bike negotiates hairpins at 35-40mph better with more weight on the front.
When you're cornering hard, you have a lot of your weight on the outside pedal, so the effect of sliding your seat back is minimized.

A lot of my high speed cornering in the mountains is done while I'm pedaling. If I do quit pedaling, so I don't hit a pedal on the grorund, I certainly want the outside pedal down. I'd be surprised if many riders also unload much of their weight off the saddle and onto the outside pedal. IMO, that's a good way to hinder your control of the bike, not enhance it. I keep my weight on the saddle and only quit pedaling for a very brief period.

If you have to juggle stem lengths to make a bike fit, what is the trade-off of using a short stem length. Salesmen told me he didn't like using 80mm or less stem. Couldn't really tell me why. The bike I'm looking at would need at least an 80 to work.

Mercurymike
I have recently finished building a new bike and used a 90mm stem whereas my old bike had a 110mm stem. The reason I used a shorter stem is the new frame has a longer TT. With the shorter stem and a longer head tube I am able to get the bars higher thus reducing the saddle to bar drop and get into a more comfortable position without being too upright. I haven't noticed any huge difference in the steering regardless of what my speed is. See if you can try the new bike with the shorter stem and see - it can't hurt to ask. Everybody will always have their opinions about what does and doesn't work.