How to Measure Bike Stem Length
The Bike Stem is an important component that is often overlooked on a bicycle because it is crucial to the comfort and handling of the bicycle. We can tell you for sure that Bike Stem Length will directly affect your riding experience. So, we need to understand the issues related to Bike Stem Length.
This guide will introduce you to what Bike Stem Length is. Why is it important? And related issues, such as how to measure Bike Stem Length.
What is Bike Stem Length?
Bike Stem Length refers to the horizontal distance between the center of the steerer tube and the center of the handlebar clamp on a bicycle’s stem. It is mainly measured in millimeters and is a key component connecting the frame and the carbon fiber bicycle handlebars. It also determines your riding posture, handling, and comfort. The common length range is generally between 60mm and 130mm.
Measure Bike Stem Length – Tools You’ll Need
To measure the Bike Stem Length, you need to prepare the following tools:
- Tape measure or caliper (a ruler measured in millimeters)
- Ruler or level (optional)
- Flashlight
- Paper and pen
Step-by-Step Guide to Measure Stem Length
- Step 1: Determine the two key points, Steerer Tube Center and Handlebar Clamp Center.
- The former is the vertical pipe connecting the front fork and the frame. At the same time, the latter is the midpoint of the handlebar fixed by the handlebar riser.
- Step 2: Locate the horizontal line accurately.
- We need to measure the straight-line distances from the Center points of the Steerer Tube Center. and the Handlebar Clamp Center to the center point on the horizontal plane. You can use a level to swing a ruler over the top of the stem and then check if it maintains a horizontal distance.
- Step 3: Measure the Bike Stem Length.
- Please place the tape measure, preferably in millimeters, on the center bolt or shaft of the steering clamp.
- Then stretch the ruler to the center point of the handlebar clamp area.
- And make sure to keep it level. This is the Bike Stem Length we measure.
- Finally, record it with paper and pen. Generally, the Stem Length size range of a bicycle is between 70 and 120mm. Moreover, the Stem Length of road bikes is longer, while that of mountain bikes is shorter. But it makes people stand upright and react flexibly.
Bicycle Stem Clamp Diameter and Steerer Tube Diameter
- Bicycle Stem Clamp Diameter: The inner diameter distance of the position where the Stem front end holds the handlebar.
- Steerer Tube Diameter: It refers to the diameter of the steering tube of the front fork. and also the diameter distance at the end where the Stem is inserted into the front of the vehicle and fixed.
Bike Stem and Steerer Tube Size Chart
| Type / Application | Handlebar Clamp Diameter (Stem Front) | Steerer Tube Outer Diameter (Fork) | Steerer Clamp Inner Diameter (Stem Rear) | Common Notes |
|---|---|---|---|---|
| Classic road/MTB (vintage) | 25.4mm / 26.0mm | 1″ (25.4mm) | 22.2mm (for threaded/quill stems) | Common on older bikes with quill stems |
| Modern road / MTB (standard) | 31.8mm | 1 1/8″ (28.6mm) | 28.6mm (for threadless stems) | The most common standard today |
| High-end MTB / Aero road | 35.0mm | 1.5″ (38.1mm) | 31.8mm or 38.1mm | Used in downhill or aerodynamic setups |
| Integrated / Aero systems | 35.0mm or proprietary sizes | 1 1/4″ (31.8mm) or brand-specific | Varies (custom brand-specific systems) | For brands like Canyon, Specialized, etc. |
How to measure Clamp Diameter and Steerer Tube Diameter?
Measure Stem Clamp Diameter:
- Measure the outer diameter of the middle of the handlebar (the connection with the handlebar stand) with a caliper or tape measure.
- The general values are: 25.4mm, 26.0mm, 31.8mm, or 35.0mm.
Note: Another method is to directly remove the Stem front cover. Measure the internal diameter at the position where the handlebars are held, that is, the width inside the “circle” of the handlebar stand. Generally, manufacturers will mark it, for example, with the words “Ø31.8”, which indicates that it is compatible with 31.8 handlebars.
Measure Steerer Tube Diameter:
- Use a caliper to measure the outer diameter of the front fork turning tube.
- The general values are: 25.4mm (1 inch) or 28.6mm (1 1/8 inch).
Note: Another method is to directly remove the Stem. Measure the inner diameter of the inserted part. Or directly check the marked specifications on the carbon fiber bicycle fork, carbon fiber bike Stem, or carbon fiber handlebars. Such as the words “1 1/8” or “Ø28.6”.
Bicycle Stem Rise/Drop（Stem Angle）
Stem Rise/Drop refers to the Angle formed between the vertical line and the horizontal line, also known as the Stem Angle. It directly affects the height of the handlebars relative to the seat cushion. Generally, Stem can be flipped, so the same Stem can achieve the effect of a rise or a drop. For example, a ±6° handle, if installed upright, is +6° (upward), and if installed upside down, is -6 ° (downward).
Measure Bicycle Stem Rise/Drop（Stem Angle）
- Method 1: Directly check the logo on the Bicycle Stem. For example: “6°” or “±6°”, “17°”, etc.
Method 2: Measure with an Angle gauge or a digital Angle meter.
Fix the bicycle horizontally.- Attach the Angle gauge above the handle and align it with its axis.
- Read the Angle between the reading and the horizontal line, which is the Rise/Drop Angle.
Related Articles:
- How to Measure Bike Handlebar Sizes Correctly
- How to measure bike handlebar width
- How to remove bike handlebar grips
- How to Measure MTB Saddle Size
- Best MTB Stem 2025: Top Picks for Every Rider
- How to Change a Bike Stem
Video: How to Choose the Correct Bicycle Stem Length
Bike Stem Length is a crucial part of bicycle adaptation Settings. It is an important and key link that directly connects your front fork and handlebars. If the Bike Stem Length is inappropriate, it will cause serious harm to your body. We’ve included this video to help you quickly understand how to find the appropriate Stem Length.
Choosing the Right Bike Stem Length
After measuring the Bike Stem of the bicycle, the next need to determine whether it is truly suitable for our cycling style and body geometry. Bike Stem Length Comfort, handling, and power efficiency are all vital importance. We consider how to choose based on road cyclists, mountain bikers, and our physical conditions. Please keep up the pace and continue to learn!
Road cyclist
If you are a road cyclist, for a racing bike, you should choose one with a diameter of 100-130mm. This is more in line with the aerodynamic position. The aggressive posture can reduce wind resistance and make your ride more efficient and fast. For endurance and comfort, it is necessary to choose a Bike Stem Length range between 70 and 100mm, which can enable you to maintain a more upright and relaxed posture. And it can relieve the pressure on the neck, back, and wrists, making it suitable for long-distance cycling.
Mountain biker
For XC off-road riders, it is recommended to use an 80-100mm Stem. Choosing a longer Stem can move your center forward. Even if you are going uphill on steep and rough ground, due to traction issues, it can still help you climb efficiently.
For riders who prefer forest trails and endurance races, it is recommended to choose a shorter Stem, which offers faster steering response and better handling on technical downhill and narrow forest trails. They pair perfectly with the wider handlebars to create a modern geometric shape of the forest road.
Body Fit Considerations
Torso Length Matters:
Riders with longer torsos or arms often feel better with slightly longer stems to avoid feeling cramped.
Discomfort = Warning Sign:
If you’re experiencing back pain, excessive pressure on your hands, or feeling “stretched out,” a shorter stem might help restore balance and comfort.
Fit is a System:
Don’t assess stem length in isolation. Consider it alongside your:
- Reach: The horizontal distance from the saddle to the handlebars
- Stack: Vertical height from bottom bracket to top of head tube
- Bike Handlebar Width: Wider bars may allow for shorter stems
Related Articles:
FAQ
Will a 10mm shorter stem make a difference?
Yes. If the stem length of your bicycle is shortened by 10mm, it will affect your stretch, riding posture, and handling. Although the distance may seem insignificant, the shorter the bicycle stem. The closer the handlebars are, the more upright your posture will be. And the more flexible and fast you will be when turning.
Is an 80mm road bike stem too short?
For road bikes, the 80mm Bike Stem Length falls within the relatively short range. However, this needs to be measured based on the rider’s height ratio, frame geometry, and riding goals. If your upper body and arms are short, then an upright posture is required. Or the upper tube of the frame itself is relatively long. 80mm can instead provide an appropriate degree of extension and relaxed back pressure. On the contrary, if one pursues a race posture with low wind resistance or feels that the steering is too sensitive at high speeds, 80mm May seem too short. The Bike Stem Length, along with your seat position, reach/Stack, and handlebar width, all need to be comprehensively considered.
Do I need to remove the stem to measure it?
No. As described in the article, you only need to touch the center points of the two fixture areas to conduct on-site measurements.
What if my stem has an angle?
You still need to conduct horizontal measurements from center to center. The Angle only affects the height of the handlebar and does not influence the measurement length of the stem.
Is there a difference between MTB and road bike stem measurements?
The measurement methods of the two are the same. It’s just that the Stem Length of the general MTB Bike is shorter, and we can measure its size more quickly.
How can I know the angle and length if it’s not printed on the stem?
Most manufacturers will print the specifications on the bottom of the handle. If not, you can measure the ascending Angle with a digital Angle measuring instrument or protractor, and then measure the length using the method mentioned in the article.
How to measure a bicycle stem length?
Length or reach is the horizontal measurement of your bike stem. It is measured from the center of your steer tube to the center of your handlebar clamp along the central axis of your stem.
What does 31.8 stem mean?
31.8 refers to the size range of Stem Clamp Diameter. Its clamping diameter with the stem matches the diameter of the handlebar. 31.8 is a standard size suitable for all kinds of rides, and there is also 35mm.
Conclusion
Through the description in the above article, I believe you already know the quick and simple method for measuring the Stem Length of a Bike! It is the key factor that directly affects the fit of your bicycle. Whether you are a road race rider or a mountain bike rider, focus on handling. Understanding the bicycle stem length can help you make a smart upgrade. If you haven’t found a suitable brand of Bike Stem yet, then the carbon fiber Bike Stem provided by the Falcarbon Bicycle brand is your best choice.
