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I use a Delta Stem Raiser (maybe also called a stem extender, handlebar riser, steerer tube extender) to make my handlebars "taller" (higher up than they could typically go) on my bike's fork. I have used this raiser for months without issue.

Delta Stem Raiser installed on a bicycle's steering column

Recently, I removed the stem raiser, lent it to a friend, then reinstalled it back on my own bike. The handlebars were aligned properly and seemed sufficiently tight when re-installed. I then went on a ride and, after a stop, noticed the handlebars had become grossly misaligned. See here where I purposefully and dramatically recreated the issue for the sake of a photo.

bicycle handlebars grossly misaligned relative to the front wheel

Now I'm finding that I can't make the Delta Stem Raiser sufficiently tight on the bicycle's steering tube/steering column. If I put my knees on either side of the wheel and turn the handlebars I can move the handlebars and make them misaligned. I would say I'm using force, but not excessive force.

bicycle handlebars move with the stem riser

Please note that the handlebars are tight on the stem raiser and it's the stem raiser that's rotating on the steering column in the above gif. This never seemed to be a problem until my recent re-installation of the raiser.

I will eventually bring this into my local bike shop, but I'm still curious about why this seems to be so loose. Maybe this has been a problem that did not show itself for months and I've only just recently noticed? Is there some very simple step I'm missing? Was my stem raiser somehow bent out of shape in a way that makes it no longer viable?

What I've tried:

  • Tightening the stem raiser bolts on the column. Right now I'm using ~12Nm of force with my adjustable torque wrench
  • Adjusting my headset spacers to make sure the stem raiser is as flush as it can be with the steering tube
  • Tightening the headset cap bolt/screw in the fork/stem
  • Removing the stem raiser from the equation (the handlebars hold perfectly in this case and do not become misaligned)
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  • With the raiser removed, can you get some closeup pictures of it, especially the area around its clamp? As far as you can remember, with its own clamp bolts loose (or removed), does it feel the same as it used to? Does it feel snug or loose? My thinking is that it might have got stretched and you now need more torque to compress it. Also, if you run the bolts through from the threaded side, do they screw in smoothly (or could there be a damaged thread against which you're getting stuck)?
    – Chris H
    Nov 4, 2022 at 16:16
  • See here for closeup pictures of it imgur.com/a/ccNOeno I tightened it as much as I could comfortably do so while uninstalled. About 18 Nm. It doesn't feel loose when installed. Unfortunately I can't recall how it feels relative to how it might have a month or so ago. The bolts seem to screw in smoothly.
    – Will Haley
    Nov 4, 2022 at 17:30

2 Answers 2

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Pull the bolts, grease the threads and the bolt shoulder and washer, then put it back together.

This product has very large (I think they're M8) stainless bolts that come totally dry. Being dry often causes the exact problem you describe. Big, dry stainless-in-aluminum interfaces can cause massive frictional losses to the ability of a torque input to translate to preload in the threads, especially in a stiff part like this.

That will very likely solve it. If not, add a grip compound (fiber grip, carbon prep etc).

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  • 1
    Is that the cycle mechanic equivalent of "turn it off and turn it back on?" ;-)
    – DavidW
    Nov 4, 2022 at 16:43
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    I believe this is correct. I greased the bolt threads, bolt shoulder, and the washer, and I can no longer easily move the handlebars while holding the front wheel by my knees. I had noticed last time I installed the raiser that it was "squeaking" loudly when tightening. I would assume that's related to it being dry like you mentioned. With the grease everything seems much happier and more secure. Thank you!
    – Will Haley
    Nov 4, 2022 at 18:32
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I'd like to propose a different, more expensive, but ultimately simpler solution to this: a high rise stem.

Compared bottom of your stem riser, your bars aren't that high and your stem is pretty short. Swapping it out and directly mounting a high-rise stem to the steerer should place your bars where you want them. I'm thinking something like this (not endorsing this model directly).

enter image description here

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