The stem on a bicycle is the metal piece connecting the handlebars to the rest of the bike. Changing the height of the stem changes the dynamics of the bicycle and finding the right stem height for you is essential whether you are a casual bike enthusiast or a racing cyclist.
Bicycles are not "one size fits all" equipment. Even inexpensive bikes allow riders to modify the fit by changing seat height or stem length. Riding a bike that doesn't fit your body puts strain on your joints and back and can lead to serious aches and pains. If you find yourself unconsciously scooting forward on the seat as you ride, the stem is too long and it is forcing you to hold your arms too rigidly. If you scoot back, the stem is too short. If you get aches in your back, neck or hands, the stem may be too short, forcing you to ride in an unnatural position.
Long stems require you to make large motions to steer and make it easier to steer the bike by shifting your weight. Short stems allow you to steer with smaller, more precise movements. Short-stem bikes require less effort to steer, but may feel unstable to riders not used to the fine movements involved. Long stems make it easier to shift your weight forward, which is an advantage when struggling up a steep incline, while short stems allow you to shift your weight to the rear, which is an advantage when going downhill.
Power vs. Endurance
Racing cyclists use short stems so they can ride hunched over, keeping their backs as flat as possible. This gives them less wind resistance and allows them to direct more power from their legs to the pedals. However, this intense method of cycling is exhausting and is not effective for long bike rides. Long stems allow cyclists to ride upright and expend less energy, so they are more suited for long-distance cyclists or touring cyclists.
Which Is Better?
The right stem length for you depends on your type of cycling. Racing cyclists prefer short stems. Casual cyclists or mountain bikers tend to want longer stems. The cycling website BikeRadar says as little as a 10-millimeter difference in stem length can significantly change the way a bike handles. So, the best option is to try several different stem lengths and find the one that is best suited to your body, your bike and your cycling style.