If your riding position position doesn’t feel quite right then you might change some components to improve it. One of them could be a quill stem. In this article we will show you the science behind it, how to choose a replacement and how to fit it.
A quill stem is used on bikes with a threaded steerer tube. It is usually one piece unless the angle is adjustable. The threaded stem sits in the steerer tube of the fork. The locking mechanism consists of a quill, a stem expander bolt and a wedge. By tightening the stem expander bolt, the wedge is drawn up and it pushes against the angled part of the stem until both parts compress into the steerer tube. The result is that the bolt will no longer tighten and the stem is tightened securely into the steerer tube. Quill stems come in two common diameters, 1″ and 11/8″.
To change your upper body position. you can replace your current stem with a different length, height or angle.
Different quill stem lengths
If you are looking to replace your quill stem with a longer or shorter one then first measure the length of your current stem. The measurement is taken from the middle of the stem bolt to the middle of the bars and is expressed in millimetres.
If your quill stem is shorter than 130 millimetres, then you will be able to source a longer reach replacement.
If your threaded stem is longer than 40 millimetres, then you will be able to source a shorter replacement.
Different angles
You can change your stem to one with either a positive angle or a negative angle.
Stem with a positive angle. This type of stem can replace a negative rise or flat stem to bring your body position more upright.
Stem with a negative angle. This type of stem can replace a positive rise or flat stem to give a more aerodynamic riding position
Adjustable stem. An alternative option offering a variety of angles to find the most comfortable position.
Different heights
If your stem is adjusted to the maximum height and it still feels too low you may be able to replace it with one that has a longer stem tube. First you will need to measure your current stem tube.
- Using a 6mm allen key, loosen the top bolt.
- If the bolt comes up whilst unscrewing this means that the stem is wedged in and needs to be loosened.
- Gently tap the bolt with a mallet or hammer until it drops.
- Move the handlebars to make sure that the stem is not seized.
- Now raise the stem above the maximum insertion mark and tighten the stem bolt.
- Measure the distance in mm between the insertion mark and the top of the stem.
- If it is shorter than 300mm you will be able to source a longer replacement.
- Now undo the bolt and return the stem to its original position.
Checking handlebar clamp diameter
Check the central diameter of your handlebars.
There are two common sizes 25.4mm and 31.8mm. Make sure that the replacement stem is the correct size.
Replacing a quill stem
Before you start be aware that when replacing a stem with a different length, height or angle you may need to replace the brake and gear cables as the current ones might be too short.
- While having the bike on the floor, stand in front of it with the wheel in between your legs.
- If you have flat bars, remove the handlebar grip on one side. If you struggle to remove it then you can find some great tips on how to remove old handlebar grips in our article here.
You can also watch our video tutorial here:
- For drop bars remove the bar tape. We have written a great article on how to remove and replace handlebar tape here.
You can also watch our video tutorial here:
- Undo the retaining bolts on the gear and brake levers on that side and remove them remembering the order.
- For drop bar levers the retaining bolt will be either somewhere under the hood
or, in older models, inside the lever.
- Remove any other accessories on that side, such as bell, light etc.
- Using a 6mm allen key, loosen the top bolt.
- Undo the bolt on the handlebar clamp and slide out the handlebars.
- Using a cable tie or strap attach the bars to the top tube of the frame.
- Now remove the stem.
- Fit the replacement stem into the fork and tighten it just enough to hold it in place.
- Attach the handlebars.
- If the cables stop the handlebars from being reattached, then find out which cables are too short and loosen them so that you can slide the bars in place.
- Position them so that they are central and levers are easy to reach. Read our article here if you’re not sure how to do this.
- Tighten the stem bolt.
- Refit the accessories.
- Refit the brake and gear levers. If any of the cables are too short then loosen them.
- Now align the bars with the front wheel and tighten the stem bolt.
- Replace any of the cables that are too short. In our article here you will find a clear guidance on how to replace gear cables.
You can also watch our video tutorial here:
The article here will guide you through the process of replacing brake cables.
- If you have flat bars then refit the grip.
- For drop bars, refit the bar tape.
We have also created a video tutorial to help you replace your quill stem
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