· Hugo · Repairs · 8 min read
How to Raise or Lower Your Handlebars (Threaded vs Threadless)
Your handlebars are too low, causing back pain and numb hands. Or maybe they're too high, making you feel unstable. Learn how to adjust them properly for both threaded and threadless stems.
You’re experiencing lower back pain after every ride, or your hands go numb within 30 minutes. The culprit? Your handlebars are likely positioned incorrectly—either too low, forcing you to lean too far forward, or too high, compromising your bike’s handling.
The good news? Adjusting handlebar height is one of the easiest bike fit modifications you can do at home. The bad news? There are two completely different systems (threaded and threadless), and using the wrong method can damage your bike or cause a dangerous failure.
In this guide, I’ll walk you through both systems step-by-step, so you can safely adjust your handlebars to find the perfect position.
Threaded vs Threadless: Which System Do You Have?
Before you grab any tools, you need to identify which type of stem your bike uses. This determines everything about how you’ll adjust the handlebars.
Threaded Stem (Older Bikes)
How to identify: Look at where the stem enters the frame. If you see a large nut on top of the stem (usually 1-1/8” or 1” across), you have a threaded system. The stem will have visible threads and a quill that slides down into the fork.
Common on: Road bikes from the 1990s and earlier, vintage bikes, some entry-level bikes today.
Threadless Stem (Modern Bikes)
How to identify: The stem clamps directly onto a smooth, unthreaded fork steerer tube. There’s no large nut on top—instead, you’ll see a top cap (often with an Allen bolt) and the stem clamps around the steerer tube.
Common on: Almost all modern bikes (road, mountain, hybrid) from the 2000s onward.
Quick Identification Guide
| Feature | Threaded | Threadless |
|---|---|---|
| Top of Stem | Large nut (1" or 1-1/8") | Small top cap with Allen bolt |
| Stem Design | Quill (slides into fork) | Clamps around steerer tube |
| Adjustment Method | Loosen nut, raise/lower, tighten | Add/remove spacers or replace stem |
| Age | Pre-2000s typically | 2000s onward |
| Ease of Adjustment | Very easy | Moderate (requires spacers) |
How to Raise/Lower Threaded Handlebars
Threaded stems are the easiest to adjust—you can raise or lower them in seconds without any special tools beyond a wrench.
Tools Needed:
- Adjustable wrench or socket wrench (size depends on your stem nut—usually 1” or 1-1/8”)
- Allen wrench (to loosen the stem bolt that holds the handlebars)
Step-by-Step Instructions:
Loosen the Stem Bolt: Use an Allen wrench to loosen the bolt at the front of the stem (this bolt clamps the handlebars to the stem). You don’t need to remove it completely—just loosen it enough so the handlebars can rotate if needed.
Loosen the Top Nut: Place your wrench on the large nut at the top of the stem. Turn it counterclockwise to loosen. You may need to apply significant force if it hasn’t been adjusted in years.
Raise or Lower: Once the nut is loose, you can slide the stem up or down inside the fork. The stem should move smoothly—if it’s stuck, don’t force it. Try tapping it gently with a rubber mallet.
Align the Handlebars: Make sure your handlebars are straight and aligned with your front wheel.
Tighten the Top Nut: Tighten the large nut clockwise until it’s snug. Don’t overtighten—you should be able to turn the handlebars with moderate force, but they shouldn’t move on their own.
Tighten the Stem Bolt: Tighten the Allen bolt at the front of the stem to secure the handlebars.
Important Safety Notes for Threaded Stems:
- Minimum Insertion: There should be a minimum insertion line marked on the stem. Never raise the stem above this line—doing so can cause the stem to fail catastrophically.
- Maximum Height: Most threaded stems can be raised 2-3 inches safely. If you need more height, you’ll need a stem with a longer quill or a stem riser.
How to Raise/Lower Threadless Handlebars
Threadless stems are more complex because the stem height is determined by spacers placed above or below the stem on the steerer tube. To raise the bars, you need to add spacers below the stem (or move existing spacers from above to below).
Tools Needed:
- Allen wrenches (usually 4mm, 5mm, and 6mm)
- Torque wrench (recommended for safety)
Step-by-Step Instructions:
Option 1: Moving Spacers (If You Have Extra Spacers Above the Stem)
Loosen the Stem Bolts: Use an Allen wrench to loosen the two bolts on the back of the stem (the ones that clamp it to the steerer tube). Loosen them evenly—about 2-3 turns each.
Loosen the Top Cap: Loosen the top cap bolt (the small bolt in the center of the top cap) by 2-3 turns. This releases the preload on the headset bearings.
Remove Spacers: If there are spacers above the stem, slide them off the steerer tube. Set them aside.
Remove the Stem: Gently slide the stem up and off the steerer tube. Be careful not to lose any spacers that were below it.
Add Spacers Below: Place the spacers you removed (or new spacers) below where the stem will sit.
Reinstall the Stem: Slide the stem back onto the steerer tube, making sure it’s aligned with your front wheel.
Reinstall Top Spacers and Cap: If you have any spacers left, place them above the stem, then put the top cap back on.
Preload the Headset: Tighten the top cap bolt until there’s no play in the headset (wiggle the fork—it should feel smooth but not loose). Don’t overtighten.
Tighten Stem Bolts: Tighten the two stem clamp bolts evenly. Use a torque wrench if possible—most stems require 5-7 Nm of torque. Tighten them in an alternating pattern (left bolt a bit, right bolt a bit, repeat).
Option 2: Adding New Spacers (If No Spacers Available Above Stem)
If you don’t have spacers above the stem to move, you’ll need to:
Purchase Spacers: Buy spacers that match your steerer tube diameter (usually 1-1/8” for modern bikes). Spacers come in various heights (5mm, 10mm, 20mm, etc.).
Follow Steps 1-6 Above: Remove the stem and add the new spacers below it.
Check Steerer Tube Length: Make sure you have enough steerer tube length. The steerer tube must extend at least 3-5mm above the top of the stem (or top spacer) for the top cap to work properly.
Important Safety Notes for Threadless Stems:
- Steerer Tube Length: You can only raise the bars as high as your steerer tube allows. If the steerer tube is too short, you’ll need to either cut it less (if uncut) or install a stem riser.
- Headset Preload: The top cap bolt is critical—it preloads the headset bearings. If it’s too loose, you’ll have play. If it’s too tight, the steering will feel stiff and the bearings will wear prematurely.
- Stem Clamp Torque: Overtightening the stem bolts can crack the stem or steerer tube. Undertightening can cause the stem to slip, which is extremely dangerous.
Alternative: Using a Stem Riser
If you’ve maxed out your adjustment range (threaded stem at minimum insertion, or threadless stem with no more steerer tube), a stem riser can add 2-4 inches of height.
For Threaded Stems: A stem riser replaces your existing stem and provides additional height.
For Threadless Stems: A stem riser sits between your existing stem and the steerer tube, effectively extending the steerer tube upward.
Note: Stem risers add weight and can affect handling, but they’re a safe solution if you need significant height adjustment.
Alternative: Replacing the Stem
If you need to lower your handlebars significantly, or if you want a different reach (how far forward the bars extend), replacing the stem might be the better option.
Stem Angle: Stems come in different angles (0°, 6°, 17°, 35°). A positive angle raises the bars; a negative angle lowers them. You can also flip most stems upside-down to change the angle.
Stem Length: Shorter stems bring the bars closer (reduces reach); longer stems push them further away (increases reach).
Common Mistakes to Avoid
Raising Threaded Stem Above Minimum Insertion: This is extremely dangerous and can cause the stem to break.
Overtightening Threadless Stem Bolts: Can crack the stem or steerer tube. Use a torque wrench.
Forgetting to Preload the Headset: On threadless stems, the top cap must preload the bearings before tightening the stem bolts.
Misaligning the Stem: Always ensure the stem is aligned with the front wheel—riding with a crooked stem affects handling.
Using Wrong Size Spacers: Threadless spacers must match your steerer tube diameter (usually 1-1/8”).
When to Seek Professional Help
While handlebar adjustment is generally a DIY-friendly task, consider professional help if:
- Your steerer tube is carbon fiber (requires special care and torque)
- You’re unsure about headset adjustment
- The stem is stuck and won’t move
- You need to cut the steerer tube (threadless) or install a new fork
- You’re experiencing headset play or grinding sounds after adjustment
Handlebar Adjustment FAQs
How much can I raise my handlebars?
Threaded stems: Typically 2-3 inches, limited by minimum insertion line. Threadless stems: Limited by steerer tube length—usually 1-2 inches with spacers, more with a stem riser.
Can I lower my handlebars on a threaded stem?
Yes, simply loosen the top nut and slide the stem down. Make sure you don't go below the minimum insertion line if raising it back up later.
Do I need special tools?
For threaded stems: Just a wrench. For threadless stems: Allen wrenches and ideally a torque wrench for safety.
Will raising my handlebars affect bike handling?
Yes. Higher handlebars make the bike feel more upright and stable but can reduce aerodynamics and make descents feel less confident. Lower bars improve aerodynamics but can cause discomfort.
Can I use a threadless stem on a threaded fork?
No, they're incompatible systems. You'd need to replace the entire fork to convert from threaded to threadless.
How do I know if my headset is adjusted correctly?
Lift the front wheel and turn the handlebars. They should turn smoothly without play (looseness) or binding (resistance). If there's play, tighten the top cap slightly. If it binds, loosen it.
Summary: Find Your Perfect Position
Adjusting your handlebars is one of the most impactful bike fit changes you can make. Whether you’re dealing with back pain, numb hands, or just want a more comfortable riding position, understanding your stem type (threaded vs threadless) is the first step to safe, effective adjustment.
Remember: Safety first. If you’re unsure about any step, especially with threadless stems and headset adjustment, don’t hesitate to visit your local bike shop. A properly adjusted bike is not just more comfortable—it’s safer too.