I'm wondering about using a quill stem in a steel threadless fork - this is for a folding bike project I'm contemplating so my ability to just get a fork and stem (for a reasonable price) that are an appropriate match is somewhat limited (probably not impossible, and I'm looking, but might take a while/never happen, SO:

Let's say I find a threadless fork, with a steel steer tube, and the wall thickness of that steer tube is comparable to a threaded fork - could I just use a locking collar clamped onto the steerer in lieu of a stem? I'm imagining I could apply the preload by means of a threaded rod or strap through the steering tube to compress the stack, then clamp down the collar, remove the rod, and install the stem. Or maybe get a steel stem and just grind off the actual stem and use it as a collar?

My impression is that what I'm describing is basically exactly a soma quillinator: https://www.somafab.com/shop/soma-he...attr=3902,3647 (and if I had to buy a new headset anyways I might just use that).

Are there any special considerations to this that I'm unaware of?

1... why?
2... expense, extra time wasted, no way to correctly set headset preload, etc.

Seems like something only a person that likes to jury rig stuff will like. If it's a matter of living where you can't possibly obtain the correct stuff, then anything goes. But that's not you is it!

Virtually all threadless stems make it easy to change the bars or swap stems without having to remove stuff from them. I've only seen a very few quill stems in 67 years that allow for easy bar or stem swap. And those were in pictures. Never seen one for real.

If you’re getting a replacement fork, why not just get a threaded fork and headset and just do it the right way?

Dan

i'm kinda thinking it may be to create an easily twistable stem for a more compact folding bike during transport.. braze or weld a "wing" on the top of the drawbolt, maybe?

or a longer stem, if the bike is tiny in size.. ?

and it could be because of what is available/at hand, too... many people can't afford a list of new parts....

the problem becomes finding a steerer that is 1 1/8 od, and 1" ID... three bmx forks near me measure (2)24.6 and (1)25.05.... the 25.05 is a cro-mo fork, so it isn't going to be inexpensive....
a couple 26" MTB suspension forks just measured at 25.3-ish, so a strong maybe! they are cro-mo tubes, i'd bet, just by looking at the very light rust... all of my straight steerer rigid forks are out in the storage... the cro-mo ones would be similar to the Susp. forks.

if a replacement 1 1/8" threaded fork is needed, they are kinda Rare, not many used ones are available, and the length needs to be really close to the original fork, or they won't fit.

Sounds feasible, although not ideal - you'll need to remove the stem any time you want to preload the headset. Sheldon Brown's Thorn Raven had both quill and a'head stems, with the Rohloff shifter on the upper flat handlebar and brake levers on the lower drop handlebar.

For carbon fiber, you absolutely need the top cap to keep the preload. It's probably never a bad idea even on steel.

I just want to check my understanding. You want a quill stem on a threadless fork. The only advantage that a quill offers is that you can adjust the height. I suppose you could turn it sideways by only loosening one bolt it single bolt threadless stems exist.

I have quills on a couple of my bikes. No complaints. I can't really see going to the effort if the fork is already threadless.

What could be easier to turn sideways than a threadless stem ?

I will never understand silly stuff like this. 1 1/8 quill stems are super uncommon. I think maybe Trek in their infinite overcharging for less might still do it on some of their lower end hybrids but it was never super common. The threadless stem is much superior in just about every way and the options for stems are so vast and varied you can usually find one that fits your needs.

a quill stem.
one bolt, with no steering bearing re-adjustment... and the quill can usually be pushed down into the steerer some, to make a more compact package.

You have to set the preload when you straighten it again, but that's no big deal. Probably better to use a locking ring below the stem if you have enough steerer, though.

I don't understand this. If the stem is properly tightened after the headset is adjusted, how does the top cap maintain the preload?

Amazing how often I find my meager needs so satisfying.

Have a nice day

It seems that no matter how tight the stem is, the steerer is slick enough to gradually loosen.

I had a bike with no compression plug and would put a piece of threaded rod in and tighten, then remove. I'd get 3 or so rides before needing to do it again. This was back when carbon forks had aluminum crowns so you could do this. It would have crushed the steerer to make it any tighter.

Once I got a proper plug, it never came loose again.

Also, a proper plug for a carbon steerer resists crushing force from the stem. It makes the whole system stronger/safer.

Steel and aluminum aren't so particular.

the plug maintains the diameter of the rather flexible CF/epoxy material, allowing the clamping force to remain consistent.
the cracks happen when the epoxy is flexed or stretched beyond it's yield point.
carbon fiber material has an amazing Tensile strength, less compression strength, and not much resistance to flexing.
the epoxy resists flexing far better, but is still lacking, compared to most metals.
the cf and epoxy are both far lighter than metals, so they can be made thicker, and still be lighter than metals.
seat stays were the most common fail point of CF frames in recent years.. they are under compression and flexing loads, and are much thicker tubes now.
the original CF frame fails were at flexed joints.. now those joints are wrapped with extra materials, but the central portions of main tubes under tension can then be thinner..
recently improved vacuum and compression of the epoxy/cf during the curing makes the materials more consistent, and stronger too.

trade offs.
and the aluminum plugs add enough weight to negate any gain from using a CF steerer, instead of aluminum, from what i've found....

OK, good to know. This has not been my experience, though, on two aluminum and one steel steerer. I can see how this might happen on a carbon fiber steerer since the stem bolt tightening torque is more critical (and probably less).

On one of my bikes, the factory instructions for adjusting the headset are:
1) Loosen stem bolts
2) Tighten top cap to eliminate play in headset
3) Tighten stem bolts
4) Tighten top cap to a specified torque.
It would seem to me that if the stem were able to slide on the steerer, step 4) would result in excessive headset bearing tightness.

interesting... that bike's factory recommended method is exactly like i've been doing all along.. and took endless grief for describing in a thread once.
thank you..
set bearing preload with cap and screw, tighten stem-to-steerer clamp screws (alternating between top and bottom screws), give the cap's screw an extra bit of torque.....