Inexperienced Question - lower or longer stem

[dohearne]

Last year was the first full year on my Serotta and by the end of the season I was a stronger and better rider. I was proud of my time in the drops until I saw the pictures from my end of the year century and realized how up right I was. I also felt that a different configuration would allow me to be comfortable and more streamlined. The question is how should I change my bike set-up first - lower my stem or make it longer? I can flip my stem, take out spacers, or buy a new stem.

[Sandy]

Excellent question. I am also interested in responses. I am thinking of getting a 12 cm stem instead of my 11 cm, and having less spacer height below the stem. You should realize that if you keep the stem that you are using and take out spacers below the stem, the bars will be further out because of the head tube angle. I already flipped my stem, which is a plus or minus 6 degrees.

Sandy

[dgauthier]

Why not see your Serotta fitter? You seem to be pleased with the results so far. It is common to move the handlebars lower and forward as a rider's flexibility improves. Let your fitter be your guide . . .

[Sandy]

Your inexperienced answer seems like an excellent one to me.

Sandy

[Tmogul]

If you keep the same stem and angle, you can calculate the forward distance moved by:

cm drop x (cos of HTA) In other words if your HTA=73 then for each cm drop of stem you move forward roughly 0.29cm.

[CNote]

:no: Stems seem to be a sensitive issue on this forum. My suggestion would be to take some spacers out and see how it feels. That's the cheapest experiment. Flipping the stem would probably be a more drastic difference. You can get spacers in different thicknesses if need be, but you can't change the angle of the stem.

[Dave]

If you make a fairly accurate graphical representation of your torso, arm and hip to brake hood lengths, you'll find that lowering the stem/bars by 1cm actually requires about a 1.3cm shorter stem to maintain the same torso angle. The .3cm is due to the angle of the steering tube, moving the stem forward. The 1cm comes from the fact that the arms and torso are in the rough range of 45 degrees, where there is approximately a 1:1 height to length ratio.

With this in mind, don't drop the stem and lengthen it at the same time, or you'll get a huge dose of change.

If your primary goal is to be less upright, then lower the stem by removing no more than .5-1cm at a time. If you have a very conservative position, 1cm moves may not be too extreme, but as you approach the limit of your tolerance for a low torso angle, even a 5mm change can feel pretty large.

If lowering the torso angle creates noticeably more weight on the hands, it either means you lack the abdominal and back strength to maintain the position, or the saddle may be too far forward.

What I use for an estimate of adequate stem length is arm to knee clearance when riding in the drops, with my upper back horizontal and my fingers in reach of the brake levers. If there is no arm to knee interference, there is no need for a longer stem. A lot of riders may find this stem length a bit too long when on the brake hoods.

Flipping a stem, like an 84/96 degree from the high rise position to the 84 degree position lowers the bars about 2cm and also increases the horizontal length of the stem by nearly 1cm, so it's a huge change. Flipping an 80 degree stem lowers the bars about 3.5cm and lengthens the stem by more than 1cm.

[Sandy]

When I flipped the 96 degree stem, I added a spacer below the stem simultaneously, so that the change would not be too much at once.

Spacer Spaced Serotta Sandy

[Dave]

That was wise to add spacer below the stem after changing from a 96 to an 84 degree stem angle, but most often this is not possible, unless you have 1cm or more of spacer on top of the stem. The only other way to gradually come down from a 96 degree stem is with a 90, to produce about a 1cm lower bar.

[BURCH]

A lot of buddies that I ride with have flipped there stems on both road and especially mtn bikes (more aggresive climbing position). Doing that requires that you are a pretty flexible person to be able to handle the extreme change that is about to occur with the flip. However, it is an easy change to undo if it feels too akward a position.

[Sandy]

I had a very wise fitter, Smiley. We decided not to cut the steerer tube until I got my fit dialed in, and to have flexibility for future changes. I originally had 2 cm above and 2 cm below the stem. Now I have 3 below and 1 above. I am probably going to try a longer stem sometime (12 cm), and less spacer height below the stem (sometime). I will probably then cut a little off the steerer tube. My bike may not look as balanced as others, but I have flexibility for changes and a higher front end that I needed.

Needy Sandy

[Sandy]

It makes little sense to me as to why "superior" fitters often leave no spacers on top of the stem in a new bicycle, especially for "older" riders. What happens when a cyclist's needs change relative to fit, because of age or accident or injury or....Once the steerer tube is cut, flexibility for change is greatly reduced. People change. So will the "proper fit" of a bike change. Riders evolve. So ahould the fit.

About to have a fit because of the rain and the cold,

Showers Sandy

[dohearne]

Why not see your Serotta fitter?

I did talk to my fitter and I got his advice...which I certainly don't discount or ignore. But this forum brings a wide range of opinion and information that I also wanted. I especially appreciate some of the more analytical feedback, that allows me in the future to better understand what I am doing when I change my bike.

A follow-up question: assuming that I can make an identical change in reach through either lowering or lengthening the stem, which would make a more noticeable change in handling? My presumption is that lengthening the stem is more radical in terms of bike handling, is that correct?

[Dave]

It's a common misconception that changing the stem length by one size will affect the handling significantly. It will increase the length of the "steering arm" which is a straight line from the center of the steering tube to the contact point on the handlebar. A change from an 80mm to a 120mm stem only changes the steering arm length by about 15%, so a 10mm change makes little difference.

If you put a bike and rider on scales, you'll note that lowering the torso angle increases the weight on the front end. Once again, lowering the stem 1cm won't make much of a difference, but switcing from the more upright brake hood position to the lower drops position will cause a measureable increase in the weight on the front.

What I haven't mentioned up to this point is the arm to torso angle. For a given torso angle, a higher and longer stem increases the arm to torso angle (more stretched out). If you have a stem that's much longer than needed to provide knee to arm clearance, then the angle between the arm and torso can become too extreme and cause shoulder pain.

The bottom line is to keep the stem just long enough to avoid arm to knee interferance and use stem height changes to adjust the torso angle.

[Dave]

Extra spacers are OK for beginners or those searching for a new position, but I can't see the need for the experienced rider. As long as you're using an 80 or 84 degree stem, there are plenty of ways to raise the stem without a big (ugly) spacer stack.

If you have a minimum of 1.5cm of spacer under an 84 degree stem, it can be flipped and some of the spacers from under the stem placed on top for a temporary height change of anywhere from +5mm to +20mm.

If a person really needed to raise the bars very much, a new set of cables, particularly the front brake, would quickly be needed.

[Tmogul]

Dave,

Are you saying that if I drop my stem 1cm that my reach to the bars will feel 1.3cm longer? Not arguing here but just want to learn. I like your idea of taking your body angles into consideration. However if one feels a bit cramped what would be the best solution? Longer stem or just lower same stem? The original poster wanted to be more streamlined so if he likes his position but wants to be lower then he simply lowers and shortens his stem? If he does this doesn't he then have clearance issues? So then a compromise is needed?

This thread is quite interesting to me. Thanks dave for all your input.

[Dave]

Dave,

Are you saying that if I drop my stem 1cm that my reach to the bars will feel 1.3cm longer? Not arguing here but just want to learn. I like your idea of taking your body angles into consideration. However if one feels a bit cramped what would be the best solution? Longer stem or just lower same stem? The original poster wanted to be more streamlined so if he likes his position but wants to be lower then he simply lowers and shortens his stem? If he does this doesn't he then have clearance issues? So then a compromise is needed?

This thread is quite interesting to me. Thanks dave for all your input.

That's a pretty accurate statement.

As for what to do if you feel "cramped", that would depend on whether you have knee to arm clearance. If you do, then I'd try dropping the stem, with no change in length, but I'd do it in 5mm increments. If a person feels cramped and has knee to arm interference, then a longer stem would be the first step.

If you look at the pros riding in the drops, their bars are usually so low that very little bend in the arm is needed to position the upper back horizontal or even well below horizontal for the riders using a 10-15cm drop. A lot of pros also have a torso angle that's a lot closer to 30-35 degrees rather than 45, when they are on the brake hoods.

[Tmogul]

Dave,

What benefits besides aero is there for sprinters to be so low but shorter? I'm assuming that a race/sprinter type should aim for such a position? I'm a long torso short arm guy. The sprinter like robbie have really short reach but really low drop. I personally feel more comfortable lower than too stretched out in the hoods but I feel better slightly stretched out in the drops.