Threaded stem run like a threadless
 

I am not exactly running it like a threadless. I am running the threaded bearing cup on top preloading the bearing but running the headset like it was a threadless stem. My threadless stem is too long and I am reluctant to cut it in case a bike with a taller neck tube came my way.

Today, I swapped out my quill for a clamp-on type stem on my road bike.
Kept my threaded fork and inserted one of those posts to convert it. Awesome alteration.
Many years in the making, with me finally needing a higher bar and 20mm shorter stem.
Fought this for ages (procrastination? :50:), until deciding my deltoids & neck could no longer handle the reach.
Good luck on your project. Show us all some photos.

I can't figure out what you're describing.

What are you reluctant to cut - the steer tube? The stem? If stem, why not just get a shorter (less tall) one?

Can you post a photo of what you've done?

This is generally what is used to convert a threaded fork/headset to a threadless stem:
https://i.ebayimg.com/images/g/lxYAA...JK/s-l400.webp

That quill to threadless conversion wont quite look right on it. Here is the pic.
https://cimg0.ibsrv.net/gimg/bikefor...7452237396.jpg
https://cimg2.ibsrv.net/gimg/bikefor...bf2e4d7d22.jpg

The steering bearings are preloaded by the 1 piece cup and locknut. The threadless headset is put on top of it and tightened to the threaded portion that is sticking above the locknut and keeps the locknut from backing out.

So it looks like that fork is threaded so it is not designed for a threadless stem and the threadless stem is not going to get the support it needs being run on those threads and the bearings weren't mean to be crammed on top of a stem. I think you just need to face the facts you need a proper threadless steerer tube so probably a new fork or just use the fork properly and get a quill adaptor as shown by Camilo . It looks like from your photos you have a threadless stem with a headset so not sure why you wouldn't use that one. My guess is both are of equal quality and probably equally worn out but I would rather have the proper fork for the stem I want to run rather than trying to run things dangerously because???

SR Suntour makes some pretty cheap 1 1/8" threadless forks that would give you similar suspension qualities but in a new fork that will work with your stem or if you have a co-op nearby you could get something there or get a Sunlite or MSW/Dimension threadless steel for for like $80-100 and call it a day.

You can't do that. The steerer is going to snap along the threads just above the headset or just below the stem, and then you will be missing teeth or dead.

Oh, Ok. Threadless quill to 1 1/8th it is. Or can I just get a 1" quill ? The threadless needs a larger diameter center handlebar also.
My threadless stem is too long. And I dont want to cut it and well, I'll see where this bike's forks are. Might as well stay with that.

I found a fork set that may be from this bike. But it seems to have been stuck. I will try to open it up and see what its problem is.

I still don't get it. How can you "cut" a threadless stem. Here is one - can you describe what you'd cut?

https://th.bing.com/th/id/OPHS.tQUNc...dpr=3&pid=21.1

For handlebar diameter, you can get shims which work just fine.

https://i.ebayimg.com/images/g/A0oAA...eXZ/s-l640.jpg

You can't put a 1 1/8 fork (you say quill, but you are talking about the fork steerer tube - the thing with threads) in a bike built for 1". You can buy a 1" threadless fork. Or you can use a quill stem:

https://cdn.sanity.io/images/cwkbno5...format&fit=min

The fact that you don't know the terms and did what you showed us means that you don't know anything about the safe assembly of bicycles. So please stop doing stuff until you have more information or you are going to get yourself killed.

I think I am mixing motorcycle terminology with bicycle terminology. The steerer tube in cycles is called stem in motorcycles.
The steerer tube seemed 1"+ longer than I would have liked, and worse yet that fork doesn't come apart or I've not figured it out yet, and has a sort of grind to it when I compress it.

I do have one of these on order for a different bike. This bike I think I'll go with the threadless cos it requires the fewest number of parts.

Specialized alloy fork with threaded steel steerer, threadless 1" headset, expanding plug in steerer, threadless stem. Works just fine.

https://cimg0.ibsrv.net/gimg/bikefor...d9121564e7.jpg

TBH the threaded steerer is a far better design than the threadless. Motorcycles are setup with the same type. Dual lock rings to preload the bearings. Much better adjustability and much better for bearing life. Ofcourse, bicycle bearing are a lot easier to get to and grease/change and the lighter threadless design with fewer parts and cleaner look I guess won out. Besides I think the manufacturers have a new thing to advertise and make everyone feel like they need to "upgrade"

What leads you to believe that bicycle threadless headsets are hard to set or don't last as long?

I didn't say this exactly. I have no experience with building a threadless headset. I have had 2 bikes that were, but I never messed with the headsets.
I am saying threadless will never work in a motorcycle.

But you implied it, based on your experience with something other than bicycles.

All sorts of motor engineering stuff just doesn't apply to bicycles. Low mass, low RPM, low power, low speed, low traction. Threadless is a better design, because it is simpler, lighter, more corrosion resistant, requires fewer tools, is easily adjusted and gives identical bearing life -if not better because it is easier to get adjusted in the first place.

I'll acquiese to that. If you remember, the bicycle came first. The motorcycle is scaled up from the bicycle.
Just for laughs - This is what I need to do the neck bearings on a motorcycle.
https://cimg4.ibsrv.net/gimg/bikefor...73c0d4b9fe.jpg

A bearing service on any motorcycle will run you 200-1000+ depending on the bike. Threadless can be adjusted in a few seconds costing nothing.. Huge advantage.

He means cut the steerer, not the stem.

Threadless headsets are superior. They weren't just introduced to fleece consumers, the steerer/bearing/stem assembly is more rigid than a threaded headset and quill stem, lighter and easier to adjust the bearings. The quill has easier height adjustment, but that's the only advantage it has that I can think of.

The quill stem has the advantage of "set it, lube it and forget it" on the bearings. Atleast it is on motorcycles.
Or, I am thinking one lock nut locked by the other locknut is better. The threadless has 1 much smaller nut/bolt, sitting much further away. But I guess in small light duty applications its the same. I infact like motorcycles that have a grease fitting in the steering neck and swingarm pivot too. That hasn't been on motorcycles since the 70's.

Yet with the early MtBs we saw a lot of headset loosening up problems. Enough so that even after a number of threaded headset, having additional steerer clamping within the threaded top/lock nut, were brought out another all together different design was tried and kept because the new design worked better for longer. Threaded steerers were the old standard, threadless ones with associated different stem and headset are the new standard. Andy

It doesn't sound like much motorcycle knowledge applies.

Motorcycles don't use a quill stem.

Threadless bicycle headset adjustment is secured by the top cap bolt AND the stem clamping on the steerer.

Bicycles and motorcycles front end assemblies of any kind have practically nothing in common. And motorcycles switched to tapered bearings a few decades ago.

Motorcycles have a welded nut on top of the triple clamp to hold down the top triple clamp. I guess they used that threadless friction fit top bolt method to the limit but welding that tension fit nut in place.

I've never seen anything remotely like that.

No bearing is set it and forget it, that is how you run into problems down the road, every bearing ever made needs some sort of check and lubrication and replacement at some point maybe no lubrication for the solid lubrication bearings but any bike I have ever seen will need bearing service at some point. It is just the nature of moving parts bearings are finite. Maybe someone has an application where they could last forever but not for a bicycle realistically unless you don't ever use it.

I think you are being just a little bit alarmist here.
I did this very thing when I was building a bike for myself during the Covid shortages and threadless forks and headsets were unobtatium.
I left the steer tube full length and clamped on a threadless stem.
I understand the concern about the minor diameter of the thread possibly compromising the strength of the steer tube but I regularly inspect the inside of the tube with a borescope and no sign of failure so far,
https://cimg1.ibsrv.net/gimg/bikefor...b69af0626.jpeg

https://cimg3.ibsrv.net/gimg/bikefor...34db19b58.jpeg

OMG, every motorcycle made after 1975 is like that Or threaded outside or threaded inside etc etc.3 ways to secure that area. Bearing, then dust seal, then lockring #1. Then lockring #2 then triple clamp. Then nut/bolt locking top triple clamp to the steering stem (yes that's what motorcycle terminology is). Here.
https://cimg1.ibsrv.net/gimg/bikefor...ab14a7e61a.jpg

The quill is the part of the stem that wedges inside the steerer - motorcycles don't have those.The top-race-to-steerer thread isn't fully engaged, it's easy for the top race to fret against the thread on the steerer, damaging it or loosening the locknut. If a threadless headset comes loose when you're out on a ride you only need an Allen key to adjust and lock it. Quill stems are also a problem, they're only tight by the wedge at the bottom of the quill, the part that emerges from the headset is just a sliding fit, but that's where a sprint will stress it.
The stem clamps the steerer, and locks the compression ring which holds the top race centred. The screw on top of the stem is only used to apply preload to the bearings before the stem is clamped.