The stem of a mountain bike is the piece that connects the handlebars to the tube that controls the steering of the front wheel. The shape of the stem effects the riding position of the person. If the stem is longer, the rider has to lean further forward to reach the handlebars. For example, cross country and long distance riders prefer longer stems because leaning forward reduces the amount of air drag on the body. Mountain bikers on the other hand benefit more from shorter stems. Because they are usually biking over rough terrain it is imperative that they be able to see what is in front of them. The further out they have to reach, the more the riders have to strain their necks up to see. Ultimately, the length of the stem, even if it is only a difference of a few millimetres, can make a huge difference to the comfort of the rider as well as the performance of the bike.
Positioning has a big impact on how the bike steers and navigates, as well as how long a rider can comfortably stay on the bike. To find a mountain bike stem that fits the rider as well as the bicycle, shoppers need to decide on which kind of stem to purchase as well as its length, construction, brace size, and clamp size.
Mountain Bike Stem Types
There are three types of stems to choose from; quill, threadless, and direct mount. The kind of stem to get is determined by headset and fork on the bike; the design of these is set up specifically for one of the three stem types.
Quill Mountain Bike Stems
The quill stem, or threadless stem, is considered to be more old fashioned and come in 1-inch, 1-1/8-inch and 1-1/4 inch sizes. The 1-inch stems have been the standard for many years, but now other sizes are just as widely used. These stems look slender and smooth and they do not rise higher than the bike's headset. The advantages of using a quill stems includes that they can be minutely adjusted in height, they are easily removed, and they are more attractive than threadless stems.
Threadless stems are a newer design that has become more popular than the quill setup. Rather than being held in place by threads, these stems connect to the steerer tube by driving a star-nut into it. Two flanges then hold it in place. These come in sizes of 1-inch, 1-1/8-inch, 1-1/4-inch or 1-1/2-inch. They are more bulky in appearance, but they can be made out of more lightweight materials than the quill stems can. Threadless stems also avoid the issue of the headset being stripped out and having to be replaced.
Like the other two stems, direct mount stems are designed for specific bikes and cannot be swapped with other stems. The overall purpose of these is to attach the handlebars and fork as securely as possible. They are short and usually range from 30 millimetres to 50 millimetres long.
Mountain Bike Stems by Construction
Mountain bike stems can be made out of aluminium, steel, titanium, or carbon fibre. Aluminium is usually the one that is used the most because it is lightweight. Carbon fibre stems are also sometimes used because of how light they are, but usually only cross-country riders have these. For mountain biking, carbon materials are generally avoided because they are too weak and have a high tendency to break.
Titanium stems are very high quality because the metal is light but just as durable as steel. It can also flex in crashes instead of break. Unfortunately, though, shoppers have to fork out more money if they want a titanium stem. Lastly, steel is very sturdy and unlikely to break, but it is the heaviest material to choose. Usually only the lower quality mountain bikes come with them.
Mountain Bike Stems by Length
The main purpose of switching out the stem is to adjust its length. Changing the length affects the posture of the rider as well as how the bicycle steers. A long stem forces the rider to reach further forward and flatten their back. With this position, steering is slower, but the front tire gets more traction. A shorter stem results in the rider sitting more in the centre of the bike with an upright, curved back. Shorter stems work best for uphill biking. With the centre of gravity being further back, the rider is more comfortable and can steer better.
The length of the bicycle stem is measured from the centre of the handlebars to the headset. It is hard to imagine how much length is needed to accommodate for a person's height. Naturally, people with shorter arms need smaller stems so that they can still reach. Short stems are around 24 mm and longer ones range from 60 mm to 150 mm. People can guess how the sitting position feels by getting a ruler and holding it to where the stem attaches to the frame. Then they can lean forward and hold their fists 24 millimetres past the end of the frame. To make it easier, find someone to hold the ruler. This is not a fail safe method, but it is better than guessing. Sitting on someone else's bike who has a different stem does not work either, because their handlebar adjustments are likely different.
Mountain Bike Stems by Rise and Drop
The rise or drop is the difference in height between the handlebars and the steerer tube. For example, a stem that raises holds the handlebars up higher than the steerer tube. The rise and drop is measured in degrees. The stems meant for street riding are often angled downward, while the mountain bike ones usually angle up.
Handlebar Clamp Sizes
The brace is the part of the stem that attaches to the handlebar. It is imperative that people order the correct size for their handlebars. The mountain bike stems are set up to attach to handlebars with specific diameters. The most common handlebar and brace size is 25.4 millimetres. However there are 31.8 mm bars as well. If the handlebar is designed specifically for downhill riding, it may be the larger size for added durability.
When looking at the clamps, be sure to remember that bikes either have a two or four bolt system. Simply look at the bicycle to see how many bolts it has. Anyone who wants to upgrade from a two bolt to a four bolt stem has to purchase a compatible handlebar as well.
Shopping for Mountain Bike Stems on eBay
Stems are often the parts on a bicycle that people do not think about. They are small, and most people only adjust their bikes by raising or lowering the seat and handlebars. However the stem makes a big difference too, but they are not often found at local shops.
Shopping online is a much simpler solution because it requires no travel and people who use websites like eBay can compare products and their sellers to find the best prices. There are thousands of bicycle products listed, so finding one that fits the bike as well as the rider is doable. eBay has also laid out their website in a way that makes searching for, and finding, products easy. There is a search bar on each page that shoppers can use to sort through the products. For example, if you type in "mountain bike stem", you'll be shown all of the stems that are for sale.
Look through the products and add the ones that you like to your Watch List. Since there are so many stems for sale, it is easy to lose track of the ones that you like and have to go searching all over again. Keep in mind all of the sellers are different so they must be checked out as well. Wait until you have a decent list of stems built up in your Watch List and then begin researching the sellers to see what kind of reviews they have gotten from their past buyers.
The stem is the part of the bicycle that connects the handlebars to the frame, and they dictate how comfortable the riding position is. They have the power to pull people forward and become more aerodynamic, or keep them seated upright and more comfortable. Since the stem determines the comfort and handling of the bike, they are one of the most important parts. Luckily, they are also upgradeable and customisable, giving riders more control over how they ride.
Several factors have been discussed about the process of selecting a mountain bike stem. First, shoppers have to determine whether their headset is threaded or unthreaded. Next, they have to find the diameter of their handlebar and steering tube. Choosing the kind of material comes next, and lastly, shoppers need to decide on the length of the stem as well as its rise or fall that determines how far forward they have to lean. Keeping these points in mind helps buyers find the right mountain bike stem for their bike.