Quill stem conversion

Not too long ago, over on VeloReviews.com, I was casually discussing the possibility of swapping out my forks and quill stem for a threadless set.  My initial intent was to replace my aluminum forks with a carbon fiber set and change the stem type at the same time.  Well, turns out that conversion got expedited when I ripped my stem apart while riding home from work.  With something of a timeline looming over me (this bike is how I get to work) I opted to move forward with the a conversion of the quill stem by using an adapter to allow the use of a threadless stem.  The forks will remain the same.

In the top of this picture you can see the pieces of the original broken quill stem.  On the bottom, the more modern Bontrager stem pieces.  And finally, on the bottom right, you’ll see the adapter that will allow me to mount that Bontrager stem.

Adapter pieces

The adapter that I selected is made to be “universal.”  Here, you’ll see the sleeve that I’ve removed that allows this to fit a bigger headset.  However, I don’t need this so I can discard it.  You can also see a second sleeve on the top where the Bontrager will attach.  I will need this one.  I was apprehensive about having these spacers in there – afraid that slippage might result – but so far that hasn’t been an issue.

Bolting the stem on is nothing too special.  If you doing this off the bike like I am, just be sure you’ve got the angle of the stem facing the right way.  This particular adapter gives me exactly zero vertical adjustment here, but you can get some adjustment by changing how far you insert the assembly into the top of the forks.  However, notice the minimum insertion line on the side of the adapter in the photo above.  Make sure you’ve got the proper amount inserted into the forks.

With the pieces together, the whole assembly simply gets mounted as if it were a normal quill stem.  Slide it in to the appropriate depth and tighten the screw in the center of the shaft.

Because I changed stems, I’m also changing bars.  While not truly required, I’m moving to a more comfortable bar with a more standard 1 1/4 inch diameter.  My old bars were 1 inch.

Now – we just mount the controls, tape the bars and enjoy our finished product!

6 Comments for “Quill stem conversion”



Just a note – you can flip the stem to get the bar higher as opposed to the current “dropped” angle right? Stems work both ways if I understand it right.


Yup – you are absolutely correct.  While not entirely evident from these photos, the angle of my head tube (head angle) in combination with this stem actually makes the stem almost perfectly parallel to the ground.  Flipping it over would have raised the bars and brought them slightly closer to the saddle.



I know this is a few years old, but i am thinking of doing the same on my dirt cheap commuter. u00a0Just wondering in your opinion the pro’s/con’s. u00a0I know its not a huge outlay but I could pick up another quill for pennies and I’m trying to decide if its worth the upgrade to the conversion. u00a0Any thoughts? u00a0Thanks!



This is late, judging by the post date, but just wanted to say great article. Really useful, especially with the photos. I’m on an old steel frame with a few new bits added on but was thinking the quill could be a problem if I need to swap. Never seen those adapters before so well pleased. Thanks for taking the time to document it and post.

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