A bike stem is the part of a bicycle that connects the handlebars to the steerer tube of the bicycle fork. The length of the bike stem establishes how far forward the handlebars are of the steerer tube. The stem design can be either quill or threadless. For the quill system, the stem is inserted into the steerer tube, which is threaded and no higher than the headset. A threadless system has a stem that clamps around the steerer tube and, as the name suggests, is not threaded. This type of system extends above the headset. The headset is the collection of components that provide the movable connection between the bicycle fork and the head tube of the frame.
Bike stems come in a variety of lengths, angles, and materials. Adjusting the bike stem to fit the rider can make the bike more comfortable and a better fit. Several factors should be considered when choosing the right length of a bike stem. These include the type and function of the bike and the rider's build. Learn about the types of stems available before making a final decision. Bike stems can be bought from sports and cycling shops, and online, from sources like eBay.
How Are Bike Stem Lengths Measured?
Bike stem lengths are measured in millimetres (mm). Quill stem length is measured along the section of the stem that goes into the handlebars, from the centre of the section that goes up to the centre of the handlebar clamp. Threadless stem length is measured from the centre of the steerer tube opening to the centre of the handlebar opening.
Bike Type and Stem Length
The type of bike usually dictates what it is used for and how the rider is positioned. There are three main types of bike: road and mountain bikes, and cruisers.
Road Bike Stem Length
Road bikes are built for speed and are designed with aerodynamics in mind. Riders should sit with their head and shoulders at a forward facing angle and lean forward. Although this may be uncomfortable initially, riders soon become accustomed to this position. The stem determines how far riders lean forward and for the best performance their torso should be at an angle of at least 10 degrees.
The easiest way to check whether the stem length is correct is to ask the rider to mount the bike and put both hands on the handlebars. He or she should look down, as if inspecting the front wheel axle. The handlebars should obscure the axle. If the axle is visible above the handlebars, then the bike stem is too short. If the axle is visible under the handlebars, then the bike stem is too long.
Road bike stems tend to have a 10 or 17 degree angle. The former provides a slight rise or drop, while the latter is flat in normal use. Those who mainly ride in time trials should opt for a bar that sits as low as possible, but others should opt for a stem that is comfortable and improves efficiency.
Mountain Bike Stem Length
Mountain bike riders tend to sit more upright than road bike riders as they need better control in rough terrain and need to see further. The stem length can be checked by asking the rider to mount the bike and put both hands on the handlebars. There should be a bend at the elbow of no less than five degrees, with as little pressure on the palms as possible. If there is too much pressure on the hands it is an indication that the bike stem is too short. If the rider has to move forward on the seat to get comfortable, then the bike stem is too long.
The type of mountain biking the rider engages in further determines his or her position on the bike. Cross country cyclists usually opt for longer bike stems of 80 to 120 millimetres as this makes the rider sit further forward. This is better suited to climbing. Those who do mostly downhill mountain biking prefer to sit further back on the bicycle as this provides additional stability, so they choose shorter stems.
Cruiser Stem Length
Cruisers are not built for speed or rough terrain, so comfort is the most important factor to bear in mind when choosing a bike stem. The most comfortable position is sitting almost straight up. If the rider is leaning forward on a cruiser, then the bike stem is too long. If the rider's arms are bent at more than 10 degrees, then he or she has less control over the bike and should invest in a longer bike stem.
Rider's Build and Stem Length
Items like bicycles are usually intended to fit people of an average build, but all people are not built along the same lines: torso and arm lengths vary. Riders with shorter arms usually benefit from shorter bike stems, while those with long arms should consider lengthening their bike stems. It is important to bear in mind that comfort plays a role in choosing a bike stem and what is comfortable for one person may not be comfortable for another.
Bike Stem Materials
Bike stems are made of variety of materials. Threadless stems are often constructed from aluminium or carbon, with some inexpensive models made of steel alloy. Quill stems are typically made of steel alloy. Aluminium stems are the most common as they are lightweight, strong, and affordable. Steel is the heaviest, but the strongest. Carbon stems are light, but can be expensive. They are most often found on high end racing bikes, where weight and speed are important. These stems also dampen road vibrations for a more comfortable ride.
While the material does play an important role in determining stem quality, weight, comfort, price, and engineering methods further affect these factors. In some cases, a well-engineered high end aluminium bike stem is superior to an inexpensive carbon bike stem. Where performance is a factor, specifically weight and speed, it is best to research individual stem designs and brands.
Before buying a new bike stem, check whether the existing model is reversible. This is a common feature in modern bicycles that allows the rider to turn the stem over to alter the pitch of the handlebars. Doing this can significantly alter the bike's fit.
Buying the Right Length Bike Stem on eBay
Buying the right length bike stem on eBay is straightforward. Simply type a search phrase, such as "80 mm road bike stem", into the search field, which can be found on every page, to see the listings available from eBay sellers. Narrow your search results by choosing the most appropriate item characteristics. If you would like more control over your search results, use the advanced search function to narrow or expand your search.
Before You Buy on eBay
Before buying on eBay take a moment to evaluate the item and the seller. Click on an individual listing to view the item listing page. This page contains everything that you need to make the right choice, including information such as the full item description, buying options, the seller's accepted payment methods, the seller's returns policy, and the seller's feedback details. To contact the seller with questions about a listing, click on the "Ask a question" link.
The seller's feedback information shows what other buyers think of his or her products and customer service. Use this information to form your own opinion about the product quality and service that you are likely to receive from the seller.
The best way to find the right length bike stem is by establishing which sitting position is the most comfortable for the cyclist. This varies between bicycle types, riding styles, and individual tastes. All handlebar positions are not comfortable for people of a similar build: riders with longer than average arms or torsos may need longer bike stems, while those with shorter arms and torsos may benefit from shorter bike stems.
The stem on a road bike should allow the rider to sit at a forward facing angle. If the rider is mounted with both hands on the handlebars, the front axle should be obscured from view. Cross country mountain bikers prefer to sit further forward on the bike than those who engage in downhill mountain biking. Cruisers are built for comfort, so the rider should sit up fairly straight. Leaning forward or sitting with arms bent at too much of an angle is an indication that a stem is too short or too long. Always check whether the bike has a reversible stem before buying a new one. In some cases turning the stem over improves the bike's fit.
Bike stems are usually made of alloys, aluminium, or carbon, but are also available in titanium, steel, and magnesium. Although the material plays an important role in the part's utility and performance, engineering and manufacturing methods also influence weight and strength. eBay sellers offer bike stems in a range of lengths and designs.