How to Measure Bike Stem

How to Measure Bike Stem

A bike stem is a component that connects the handlebars with the steering pipe of the bicycle fork. Also known as a goose neckline, a bike stem can provide optimum performance and comfort throughout the road if measured correctly. 

Thus, we’ve written down the steps on how you can measure a bike stem the right way, along with other factors you need to know.

Types of Bike Stems

Quill Stem

The quill stem is often made from aluminum or steel and remains the industry standard on utility bicycles and luxury retro bikes. It also has been substituted with the threadless stem as a market standard for a special sort of bicycle.

The quill stem works with a threaded steerer tube that typically comes in 1 inch and 1 ⅛ inch diameters and extends through the headset without protruding beyond it. When a quill stem is utilized, the fork steerer tube needs to be at length wherein it doesn’t float over the headset.

They are found in many older bikes and some inexpensive bikes and remain the most widely used and readily available.

Threadless Stem

A newer type of stem that is also widely popular and has replaced quill stems as the industry standard on sport bikes. A threadless stem features a modular design wherein the stem clamp around the outside of the top of the fork steerer tube which protrudes above the headset.

A threadless stem is available in lengths of up to about 5 inches and are required to have a “star-nut” driven down into the threadless steerer tube, which is held in place by two barbed flanges. The top cap then bolts into and pulls against the “star-nut” preloading the headset bearings.

Special adaptors may also allow a threaded fork to receive a threadless stem.

Style of Riding and Stems

Road

Recreational road riders often opt for longer stems that have a positive rise. A more upright position will ease tension on the hamstrings and the lower back. For less flexible riders, a stem that has a positive rise can relieve some pressure. Longer stems will allow you to easily shift your weight forward, which is helpful especially on steep inclines.

On the contrary , a short stem is usually the best choice for competitive road riders, wherein handling is more compliant and the rider sits in a more aggressive way and aerodynamic position. A short stem may require more precise movements, which can feel fidgety to inexperienced riders.

Mountain

For downhill and enduro riders, you can benefit immensely from short stems rather than a long stem, wherein handling and maneuverability will improve dramatically when descending.

With a shorter stem, handling is more responsive as you are able to  maintain a more solid position on your bike, move the bike side-to-side quicker, corner better and lift the front-end more easily. Ordinarily downhill and enduro oriented stems will have a flat, 0° angle or a very slight rise.

For cross-country and leisure oriented mountain bikers, they are more concerned with fit than handling when it comes to the stem length. recreational riders commonly have stems with a slight rise, whereas competitive cross-country racers have stems with a negative angle or drop.

Hybrid

As with recreational road riding, a longer stem with a positive rise is advisable for hybrid riders. However, if a stem is too long it can affect the bike’s handling in a negative way.

Larger frames usually have longer stems to accommodate taller riders. In contrast, shorter stems are frequently used for smaller frame sizes in order to fit shorter riders.

Generally, you can easily change the current stem length by 10 to 20 millimeter without any adverse effects on handling.

The ideal stem length for hybrid riders will depend on the fit of the bike, which is unique to every individual.

Comfort and Cruisers

An adjustable stem is a good option if you want to be as upright and comfortable as possible. However, the adjustability comes with additional weight, and an extreme upright position is appropriate for short distances only. 

For those riding thirty minutes or more, a slightly bent body position is advantageous for better muscle function and wind resistance.

Stem Material

Bike Stems are often made of aluminum alloy, but can be also made of steel, carbon fiber, titanium or aluminum alloy wrapped in carbon fiber.

Alloy stems are usually more affordable than carbon material, though some high-end aluminum stems are made of the highest grade alloys which can be lighter and more responsive than their carbon counterparts, making them  more expensive than the most affordable stems on the market.

Carbon stems, on the other hand, are built for weight and comfort on the bike. Carbon fiber has a good ability to dampen vibrations and aid in removing a large part of  “road static.”

In order to make the carbon strong and safe enough as stem material, they have to overbuild it for added strength. This is why the highest quality alloy stems can be stronger and lighter than many carbon stems.

Some bicycle companies offer titanium stems that also have their own benefits. These stems are comfortable and they look great with a Ti bike, they are also lighter than the less expensive alloy stem.

Stem Rise/Drop

A stem’s rise and drop are measured by the degree of difference from 0 or 90 degrees from the steerer tube.

Quill stems are set with a positive or negative rise or drop, or a 0-degree rise, while a threadless stem is usually measured from 0, and can often be flipped to give an equal rise or drop, but this depends on the orientation. 

On the other hand, road stems for racing bikes are often in the drop position to give the rider a dropped and stretched-out stance, while a recreational and a mountain bike typically have a rise orientation to allow for a more comfortable upright position.

How to Measure Bike Stem

What You Will Need

  • Tape Measure
  • Bike Stand (optional)
  • Erasable marker

Steps on How to Measure Bike Stem Length

Step 1: Stabilize the Bike

If you have what you need then let’s find out how to measure bike stem.

The first step you have to do is to place your road bike against something firm or stable.

Put the bike against a firm support to give you access to a good stem angle and position which will be useful for the process of bike stem measuring.

You can also stabilize your bicycle by putting it in a bike frame stand or trainer that is appropriate for the frame size. However, if these tools aren’t available, you always have an option to position your bike frame against the wall or something firm.

Step 2: Markings

Mark the center point where the stem connects to the bike frame and where it connects to the handlebar.

Step 3: Measure

Measure between the two center points using the tape measure with centimeter and millimeter markings.

Step 4: Round off

Now that you have the stem length, round this measurement to the closest centimeter to be able to determine the size of your current stern.

How to Measure Stem Width in One Step

Most modern stems use a 1 ⅛ inches stem width, but some older bikes still have one inch connections instead of 1 ⅛ inches.

There are connectors to help adapt stems and frames of different width and while you need to know your stem width, there are usually plenty of adaptor options.

Step 1

Measure perpendicular to the stem, using a tape measure.

Since the width is measured in inches and fractions of an inch, you need to use the appropriate part of the tape measure.

Since stem width measurements are fairly precise, you do not need to round off the measurement.

Steps on How to Measure Stem Rise

Stem rise isn’t measured using the inches you get in lift, which is the combination of rise and reach. Instead, it’s measured by the degrees of lift in the stem.

Step 1

To measure the stem rise you need a protractor.

Line up teh protractor so that the vertical line of the stem attachment is at the center.

Step 2

Use a pencil or another straight tool to match the angle of the stem.

The degrees that are above 0 indicate the rise of your stem. So it might be a 6 or 7-degree rise, or 0, or any measurement in between. 

You might also see the stem rise listed as the degree of the rise + 90. That’s because if you turn the protractor on its side, so that 0 degrees is vertical instead of horizontal, the rise will be between 90 degrees (0) or 100 degrees (10) on most bikes. 

Factors to Consider When Choosing Bike Stems

Know the Reach

The reach is also important because a bicycle with an insufficient reach is uncomfortable and can cause cramping.

 That is why a bicycle’s top tube length is also important to consider as it will tell you how far you can go before you meet any negative bike handling traits.

It is not advisable to put a little stem on bikes with a short top tube because it will cause bad control and riding position and you may also struggle in riding terrains as there will be a big chance that you will get lop-sided from being in an upright position.

A good mountain bike stem length is somewhere in between 50 to 80 millimeters.

Determine the Bike’s Rise

Bike stems have different amounts of rise which is also known as the bike stem angle.

For mountain riding, the bike’s front end height is usually influenced by the alloy or carbon handlebars. Thus, if you want a higher front end, you will need handlebars with more rise. However, if you want something with a lower front end, then it is best to choose flat handlebars.

Take note that when you’re in doubt, it is always best to start at a safe range of stem angles, which are somewhere around 5 to 6 degrees.

If you do have a stem below 70 millimeters, zero degrees is the best choice as this stem angle will give a neutral placement of the handlebar clamp area and will not restrict you to a too low or tall front end.

Check the Bar Diameter

This is the bike handlebar’s diameter where the stem locks on. The usual handlebars for mountain bikes is 31.8 millimeters which is bigger than the previous standard of 25.4 millimeters.

If you are unsure which diameter you have then always use a tape measure or ruler and then measure it carefully.

Stiffness is another factor you should take note of in handlebars. If you prefer something stiffer, then it is best to change to a diameter of 35 millimeters.

However, it may be a bit hard to find a bike stem or handlebars that can accommodate that because not a lot of companies support a 35 millimeter size yet. Along with checking the diameter, you also need to check the handlebar width or bar width.

Consider the Clamp Design

There are two clamps on a bike stem. A handlebar clamp at the front part and a fork steerer clamp at the back part.

Almost all good stems use a 4-bolt design for the front bar clamp which is strong, stiff and less creak-prone than the 2-bolt face plate design.

The rear clamp, where the stem fits onto the fork steerer, has a bit more variation in design.

Remember that a handlebar clamp size which usually come in millimeters, are the actual length of the road bike stem starting from the middle of the steering bore.

It’s a good idea to look for a stem that does not have rear clamp bolt heads that protrude too far because this will hurt your knees in the event of a crash. Most good stem designs have a rounded-off bolt head design.

Frequently Asked Questions

How do you find the angle of a stem?

The stem angle is measured by placing the stem on a horizontal surface and measuring the angle where the stem rises above the horizontal.

Can you flip a bike stem?

You can flip a bike stem, but this will depend if you need to slightly increase your reach. Flipping the bike stem also depends on what type of bike you have, doing this on kids’ bikes and folding bikes is easier, but flipping the stem on most hybrid or road bikes will require you new housing and cables which can be frustrating.

While the stem is an essential part, you also need to consider the seat tube, steering axis or steering column, steer tube and saddle height, head tube angle or head angle as they all have a part in providing you a good biking experience whether you are using a road bike, cyclocross bike, mountain bike or a cruiser.

Summary

Before heading to a bike shop, you need to measure the bike stem first. To do so, you will need something to stabilize the bike, which can either be a bike frame stand or just position the bike frame against a wall. Then you will need to mark and measure with the use of a tape measure and round off the result to the nearest centimeter.

Keep in mind that when choosing a bicycle stem, you need to know the reach, consider the bike rise or the stem angle, check the handlebar diameter and then finally consider the clamp design to be able to have the perfect stem and perfect bike fit.

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By Paul P.

Paul Panha is an avid cyclist and sports performance enthusiast. Regularly on the road testing (and buying) new bikes. Paul is a co-owner of GetBike.fit and is the head resident author here.