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Threadless Conversion Questions

Old 06-11-20, 03:57 PM
  #1  
tNuvolari
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Threadless Conversion Questions

In updating an 80's Italian bike to index shifting, I've decided to replace the entire cockpit and then while growing impatient on finding an inexpensive quill stem that I like, I've gone threadless! I've just bought a nice little Cinelli Bianca stem on Ebay and I also have a set ITM bars coming. My main question right now is what is the purpose of spacers? Are they purely aesthetic or do they provide support also? I'm going to use a threadless adapter such as Profile Design or similar. Do these adapters offer any space to adjust handlebar height? My stem has a slight angle to it , 8 degrees - Are there any rules on going from quill to threadless if I want to keep the same general bar placement? I realize it's trial and error but just curious what most people know about this conversion other than they don't like threadless. Personally, I like both, depending on the design. It's just with threadless, there are so many more options and it's much easier to swap out a stem or bars.
Thanks.
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Old 06-11-20, 04:47 PM
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2cam16
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Stem spacers help in your fit on the bike. If your fit right now pre-threadless feels good, I suggest getting some measurements so you can transfer them over to your new cockpit set-up.
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Old 06-11-20, 05:05 PM
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tNuvolari
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Originally Posted by 2cam16 View Post
Stem spacers help in your fit on the bike. If your fit right now pre-threadless feels good, I suggest getting some measurements so you can transfer them over to your new cockpit set-up.
I don't understand. Aren't they just shims that go between the bottom of the stem and the locking nut of the headset? They don't change fit as that's determined by the length of the fork, or in my case, the length of the stem adapter.

I can see them providing some support to the bottom of the stem but I would think and hope that the 2 bolts on the back of the stem would provide all the necessary strength.
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Old 06-11-20, 05:22 PM
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The fact that you are using a quill adapter tells me that you are keeping your existing threaded headset.

If you were going to a new all carbon threadless fork steerer then you would be doing a full “A-headset” threadless headset install.

In your case, the quill adapter has a wedge that locks down inside your steer tube by using a 6mm Allen wrench. There should be some allowable up and down movement to the threadless “quill”. Check the outer diameter of the quill adapter that fits the internal diameter of your steer tube and once you have this dimension, you could source some spacers to fill the gap between the bottom of the stem and the top nut of the threaded headset.

What diameter of ITM handlebars do you intend to go with - 31.8?
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Old 06-11-20, 05:50 PM
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Waiting for the Pictures

In a threadless fork the spacers and the stem clamping around the steering tube, allow for headset bearing pre-load when loose
and holding it like that when tight.. spacers fill in the gap. under the stem & thansfer the adjustmrnt force thru the stem

a stem raiser for threadless is when the last guy cut the fork steerer too short...

a Quill to threadless adapter is a plug to grip the stem around that goes in the fork/.
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Old 06-11-20, 09:50 PM
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tNuvolari
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So no spacers needed with an adapter....?

That makes sense; I forgot the headsets were different.
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Old 06-12-20, 07:18 PM
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1987cp
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I had a fun time learning about threadlessness and star nuts when I bought my tandem, which has a threadless headset. Turns out, the bolt that goes through the funny plug in the top end of the steer tube engages with a "star nut" installed inside the steer tube to correctly load the headset bearings. The plug thing actually pushes down on the stem as you tighten the bolt, and stem spacers transfer the downward load from the stem to the headset while the bolt pulls up on the star nut inside steer tube, and then you clamp the stem to the steer tube to lock the headset adjustment in place.

When I added something called a Delta Stem Raiser Pro to get the bars up high, it didn't go on as far as the stock stem and I had to both move the star nut upward and add extra spacers in order to load the bearings before clamping on the Stem Raiser. But that's all with a threadless steer tube.

In your threaded bike, the headset is already secured by the nut installed at the top end of the steer tube, leaving a quill stem free to be adjusted or swapped without affecting the headset at all. Similarly, the threadless adapter has no effect on the headset, just provides a place to attach a clamp-on stem at the height of your choice. Thus, no threadless stem/headset spacers are necessary.

On my "normal" bikes, I use Technomic and Sunlite quill stems to get the bars high enough, but I also use only bars with a 25.4mm clamping diameter. For what it's worth, a search turned up multiple quill stems with 31.8mm bar clamping diameters, but quill adapters still seem to be a popular option.

If it helps, check out this picture from the Velo-Orange website of how they install a clamp on stem on a bike with a threaded steer tube and headset:

https://cdn.shopify.com/s/files/1/21...g?v=1505398749

Last edited by 1987cp; 06-12-20 at 07:27 PM.
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Old 06-13-20, 12:01 PM
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did a quick infographics for ya tNuvolari
pls ignore the omitted details on the headset part and etc. tried to depict simple comparison between the use of SPACER VS QUILL ADAPTOR on threadless setup. the 'dashed line' is where the steerer tube is cut.



this pic is what i've tried with spacers once for my SS clunker. (1" steerer tube to 1" stem, the inside diameter of the spacer was hence 1").
as you see, there's one problem. where the expanding bolt is deployed inside the tube was way to far from the idealistic tightening point—right inside the top part of the headset. however, i didn't encounter a big trouble. maybe i was lucky not having had any front collision.

Last edited by orangeology; 06-13-20 at 03:21 PM.
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Old 06-13-20, 02:40 PM
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Originally Posted by tNuvolari View Post
So no spacers needed with an adapter....?

That makes sense; I forgot the headsets were different.
You don't need a quill adapter on a threadless headset. There are no threads holding the fork in place. The fork goes through the headset you will need an adapter to get the fork steerer that is above the headset to 1 1/8th inch diameter to allow the stem to clamp to the steerer. Install the fork through the headset install the adapter over the protruding steerer install spacers and stem to get desired height. You will need a stem plug/ star fangled nut at the top inside of the steerer. Install more spacers above the stem untill the top of the steerer is a 1/4 inch or more below the top of the spacers. screw the cap and cap bolt into the nut tighten until the play is gone from the fork align and tighten the stem bolts. If there is a lot of steerer above the top of the stem cut the steerer down, not recommended until you have your right fit.

Hope this makes some sense.
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Old 06-13-20, 03:17 PM
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could be some exceptions like) 1 1/8" stem to 1" steerer tube. or if desired height of the stem's too high so the start nut or expanding bolt position becomes 'too far' from the inside of the top part of the headset (so the 'end' part of the quill adaptor can do the tightening job from inside instead). and so forth etc etc.

Originally Posted by wsteve464 View Post
You don't need a quill adapter on a threadless headset. There are no threads holding the fork in place. The fork goes through the headset you will need an adapter to get the fork steerer that is above the headset to 1 1/8th inch diameter to allow the stem to clamp to the steerer. Install the fork through the headset install the adapter over the protruding steerer install spacers and stem to get desired height. You will need a stem plug/ star fangled nut at the top inside of the steerer. Install more spacers above the stem untill the top of the steerer is a 1/4 inch or more below the top of the spacers. screw the cap and cap bolt into the nut tighten until the play is gone from the fork align and tighten the stem bolts. If there is a lot of steerer above the top of the stem cut the steerer down, not recommended until you have your right fit.

Hope this makes some sense.

Last edited by orangeology; 06-13-20 at 08:33 PM.
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Old 06-13-20, 03:33 PM
  #11  
tNuvolari
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Originally Posted by orangeology View Post
did a quick infographics for ya tNuvolari
pls ignore the omitted details on the headset part and etc. tried to depict simple comparison between the use of SPACER VS QUILL ADAPTOR on threadless setup. the 'dashed line' is where the steerer tube is cut.



this pic is what i've tried with spacers once for my SS clunker. (1" steerer tube to 1" stem, the inside diameter of the spacer was hence 1").
as you see, there's one problem. where the expanding bolt is deployed inside the tube was way to far from the idealistic tightening point—right inside the top part of the headset. however, i didn't encounter a big trouble. maybe i was lucky not having had any front collision.
Thanks, everyone, for the explanation above! And Orange, love the drawing, dude! You should put that on the wall!

I guess the whole problem came from the fact I forgot that threadless stems DON'T have threads! Who woulda guessed? So something has to hold that headset together.... I've never owned or really seen a threadless stem set up in person so forgive my dumbness.

But, hey, the world now has a great new drawing so all's well that ends well....

And now some gratuitous pics of my Cinelli stem that just arrived in the mail complete with scary glowing red eyes:



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Old 06-13-20, 04:27 PM
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wsteve464
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If you have not bought a new fork yet you ca get one of the quill adapters and used the threaded steerer. Just push the adapter in tighten it and put the devil stem over it.
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Old 06-13-20, 05:49 PM
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You’re getting two sets of directions here. One assumes you are also changing out the fork to one that is not threaded. You need spacers in this case. The other assumes you are using a threadless adapter to work with your existing threaded fork. The adapter works much like a quill and does not need the spacers. They would be a nice aesthetic but I’m leery of being able to get them tight enough so they don’t jingle.
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Old 06-13-20, 09:52 PM
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Originally Posted by plonz View Post
The adapter works much like a quill and does not need the spacers. They would be a nice aesthetic but I’m leery of being able to get them tight enough so they don’t jingle.
a touch of silicone goop between spacers and the top and bottom spacers helped eliminate the jingle when I used a threadless stem in a bike.
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