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.
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.
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.
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)