Threadless Conversion Headset
05-11-18, 09:32 AM
#1
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Threadless Conversion Headset
At the risk of further hijacking the retro-roadie thread and/or my own open mold disc road bike build thread, I'm going to start a separate thread to post some details about the threadless conversion headset I designed for my Trek 660:
Product shots below:
First, it is not a standard adapter in any way. You cannot install it without replacing at least the upper headset cup, though I made a new lower cup assembly as well. Mismatched parts just don't cut it!
Second, the way it works is quite simple. Instead of having an upper threaded race that merely adds bearing preload, the upper race of the conversion headset includes a 1 1/8" tube feature. The upper race is bonded to a quill which acts both as an anchor for the tube like a standard quill stem, as a means of locking out the headset adjustment, and completes the remainder of threadless tube. Installation/adjustment is as simple as threading on the upper assembly until desired bearing preload is achieved then using a 6mm hex key to tighten the quill. By using the quill in this manner, the standard locknut on a threaded headset is eliminated, and so is the fairly annoying process of adjusting a threaded headset. Here's a cross section of the CAD file for the upper assembly:
If you look right above the cartridge bearing you can see the internal threads on the upper race that grab the fork's steerer tube (and a dust seal). Above those threads is clearance for extra steerer tube. Of course, there is a limit to just how much extra can be accommodated. The quill is expanded by turning the top cap which has a long steel stud fixed to it (threads and Loctite). The lower threads on the steel stud draw the wedge into the quill's taper causing it to expand. Fully tightened, it won't turn or pull out and the concentric expansion of the quill doesn't disturb the headset's bearings. My original prototypes used a simple top cap and a standard bolt (like a typical threadless adapter) but I hated the look and moved to this updated design:
If you look super close at the above photo you'll notice a very slight difference in the design of the upper race. That's because my Trek still has one of the original prototypes on it, minus the old-style top cap. I have also cut my conversion down to almost the minimum such that the top cap is flush with the top of my stem with no spacers underneath. I did think about more than myself when creating this and designed spacers with an internal o-ring to keep them from rattling and complete the threadless conversion look for those who don't want to run their stems so low. The o-rings were necessary because this design doesn't put any preload force on the spacers (meaning you can swap them around without messing with headset preload, too).
Any further questions?
Product shots below:
First, it is not a standard adapter in any way. You cannot install it without replacing at least the upper headset cup, though I made a new lower cup assembly as well. Mismatched parts just don't cut it!
Second, the way it works is quite simple. Instead of having an upper threaded race that merely adds bearing preload, the upper race of the conversion headset includes a 1 1/8" tube feature. The upper race is bonded to a quill which acts both as an anchor for the tube like a standard quill stem, as a means of locking out the headset adjustment, and completes the remainder of threadless tube. Installation/adjustment is as simple as threading on the upper assembly until desired bearing preload is achieved then using a 6mm hex key to tighten the quill. By using the quill in this manner, the standard locknut on a threaded headset is eliminated, and so is the fairly annoying process of adjusting a threaded headset. Here's a cross section of the CAD file for the upper assembly:
If you look right above the cartridge bearing you can see the internal threads on the upper race that grab the fork's steerer tube (and a dust seal). Above those threads is clearance for extra steerer tube. Of course, there is a limit to just how much extra can be accommodated. The quill is expanded by turning the top cap which has a long steel stud fixed to it (threads and Loctite). The lower threads on the steel stud draw the wedge into the quill's taper causing it to expand. Fully tightened, it won't turn or pull out and the concentric expansion of the quill doesn't disturb the headset's bearings. My original prototypes used a simple top cap and a standard bolt (like a typical threadless adapter) but I hated the look and moved to this updated design:
If you look super close at the above photo you'll notice a very slight difference in the design of the upper race. That's because my Trek still has one of the original prototypes on it, minus the old-style top cap. I have also cut my conversion down to almost the minimum such that the top cap is flush with the top of my stem with no spacers underneath. I did think about more than myself when creating this and designed spacers with an internal o-ring to keep them from rattling and complete the threadless conversion look for those who don't want to run their stems so low. The o-rings were necessary because this design doesn't put any preload force on the spacers (meaning you can swap them around without messing with headset preload, too).
Any further questions?
Last edited by joejack951; 05-14-18 at 05:06 PM.
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05-11-18, 09:40 AM
#2
Senior Member
Thread Starter
Basic specs:
Converts ISO 1"-24 threaded to 1 1/8" threadless (dia. 30.2mm cups, dia. 26.4mm crown race)
Sealed steel cartridge bearings with Buna-N dust seals, top and bottom
Uncut weight: 265 grams
Uncut threadless steerer tube length: 90mm
Minimum cut length: 38mm (includes 2.5mm for top cap)
Lower stack height: 12.5mm
Upper stack height: 14.6mm
Steerer tube requirements:
1. Must be 27mm min/45mm max longer than bare headtube measured from fork crown
2. Threads on steerer tube must end no more than 16mm above the edge of the bare headtube (using fork crown as reference)
Installation video:
Converts ISO 1"-24 threaded to 1 1/8" threadless (dia. 30.2mm cups, dia. 26.4mm crown race)
Sealed steel cartridge bearings with Buna-N dust seals, top and bottom
Uncut weight: 265 grams
Uncut threadless steerer tube length: 90mm
Minimum cut length: 38mm (includes 2.5mm for top cap)
Lower stack height: 12.5mm
Upper stack height: 14.6mm
Steerer tube requirements:
1. Must be 27mm min/45mm max longer than bare headtube measured from fork crown
2. Threads on steerer tube must end no more than 16mm above the edge of the bare headtube (using fork crown as reference)
Installation video:
Last edited by joejack951; 06-20-20 at 05:20 PM. Reason: Added steerer tube requirements and install video
05-11-18, 10:25 AM
#3
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Super cool as I said in your other thread. I like that you're making a silver version.
05-14-18, 07:37 AM
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Is this available for sale?
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05-14-18, 07:46 AM
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Super cool, and a creative way around this challenge of using threadless cockpits with older bikes. Yes, yes, more details please! For sale? Some old prototypes laying around that need testing********** 
05-14-18, 09:02 AM
#6
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Sorry if this sounds snarky, but I still can't get excited about threadless headsets, because of the loss of handlebar height adjustment.
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Capo: 1959 Modell Campagnolo, S/N 40324; 1960 Sieger (2), S/N 42624, 42597
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"Far and away the best prize that life offers is the chance to work hard at work worth doing." --Theodore Roosevelt
Capo: 1959 Modell Campagnolo, S/N 40324; 1960 Sieger (2), S/N 42624, 42597
Carlton: 1962 Franco Suisse, S/N K7911
Peugeot: 1970 UO-8, S/N 0010468
Bianchi: 1982 Campione d'Italia, S/N 1.M9914
Schwinn: 1988 Project KOM-10, S/N F804069
05-14-18, 09:09 AM
#7
Full Member
This looks neato, thanks for sharing!
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Some Past Bikes: '96 Bianchi Reparto Course EL OS, '96 Serotta CSI, '89 Bianchi Giro, '82 Gitane SC, '81 Gios Torino, '79 Trek 937, '77 Trek TX700, '73 Gitane TdF, '72 Follis 472, '58 Peugeot PX-10
05-14-18, 07:21 PM
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I saw an earlier thread where you demo'ed this, pretty snazzy! So you mention spacers, what is the maximum height you could have with spacers, or will there be different lengths.
Either way please send the CNC programs so I can make this out of titanium - or even better the cam files
Either way please send the CNC programs so I can make this out of titanium - or even better the cam files
05-14-18, 07:25 PM
#10
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Thread Starter
Originally Posted by Rocket-Sauce
Is this available for sale?
05-14-18, 07:31 PM
#11
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Thread Starter
Originally Posted by AdventureManCO
Super cool, and a creative way around this challenge of using threadless cockpits with older bikes. Yes, yes, more details please! For sale? Some old prototypes laying around that need testing**********
05-14-18, 07:42 PM
#12
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Thread Starter
Originally Posted by John E
Sorry if this sounds snarky, but I still can't get excited about threadless headsets, because of the loss of handlebar height adjustment.
1. Flip the stem. With a -17° stem like mine, I can raise the handlebars significantly by just flipping it over. It won't look as slick but for a long slow ride or to let a friend use for a weekend, it would do the trick.
2. Don't cut the quill all the way. If you are ok with some protruding quill above the stem when the handlebars are fully lowered, you can use the extra height to raise the bars when desired. Combined with a stem flip you could really raise the bars quite a bit, likely far more than a traditional quill would allow. Just make sure your cables are long enough for it.
3. Use an adjustable stem. Last on a list for a reason but you could swap one in for a fixed stem as desired with little fuss if you didn't want to run one all the time.
In all cases, you don't need to worry about headset adjustments like you would with true threadless which makes it less painless, just not as pain-free as a normal quill.
05-14-18, 07:54 PM
#13
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Thread Starter
Originally Posted by GrainBrain
I saw an earlier thread where you demo'ed this, pretty snazzy! So you mention spacers, what is the maximum height you could have with spacers, or will there be different lengths.
My sister's bike received an early prototype, too, and I only partially cut the quill for that install using a few spacers under the stem:
Originally Posted by GrainBrain
Either way please send the CNC programs so I can make this out of titanium - or even better the cam files
05-15-18, 06:40 PM
#14
Cyclist
Absolutely gorgeous! Well done. I'm very disappointed my regular conversion stem has been working well lately. I need more reasons to buy this! Though, really, the way it looks is enough
05-15-18, 08:34 PM
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Originally Posted by joejack951
What other specifics do you want to know? I'm out of the prototype phase. Sorry!
Beautiful piece of kit. The main questions were price and availability. I think you answered those in response to another poster.
Great work!
05-18-18, 09:15 AM
#16
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Thread Starter
Originally Posted by coolkat
Absolutely gorgeous! Well done. I'm very disappointed my regular conversion stem has been working well lately. I need more reasons to buy this! Though, really, the way it looks is enough
This threadless conversion headset yields some added stiffness as a result of using the upper race to support the quill. The upper race is supported at a far larger radial distance (by the headset bearings) than a quill on the ID of the steerer tube (15mm vs. 11.1mm). Having used a bike with a back to back comparison of threadless adapter to threadless conversion headset it really is a noticeable difference. You can actually take advantage of the extra stiffness of a threadless stem and modern handlebars now.
There is also a smidgen of weight savings vs. an aluminum threaded headset and threadless adapter combo, a number which increases when you cut down the quill. I've toyed with idea of titanium hardware and ceramic bearings for even greater weight savings but haven't yet gone there.
05-18-18, 02:54 PM
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Okay! After reading through this again, I do have some additional questions -
1. I'm assuming the cartridge bearings are replaceable - where can one find drop-in replacements?
2. Are you seeing any additional wear, especially on the top bearing, from having the torque/load of the downward force on the handlebars and stem transfer to the bearing? The way my brain is processing it...on a normal quill stem, the load from body weight follows this path: handlebars --> stem --> steerer (usually steel) --> headset. On your design, it is handlebars --> stem ---> upper headset cap. Just curious. I can see how it can be immensely more stable and stiff, but my brain keeps thinking about that 'push down' force directly against the top headset cap.
3. Is the bolt steel, and the wedge aluminum?
4. Any info on country of origin?
Thanks!
1. I'm assuming the cartridge bearings are replaceable - where can one find drop-in replacements?
2. Are you seeing any additional wear, especially on the top bearing, from having the torque/load of the downward force on the handlebars and stem transfer to the bearing? The way my brain is processing it...on a normal quill stem, the load from body weight follows this path: handlebars --> stem --> steerer (usually steel) --> headset. On your design, it is handlebars --> stem ---> upper headset cap. Just curious. I can see how it can be immensely more stable and stiff, but my brain keeps thinking about that 'push down' force directly against the top headset cap.
3. Is the bolt steel, and the wedge aluminum?
4. Any info on country of origin?
Thanks!
Last edited by AdventureManCO; 05-18-18 at 02:58 PM.
05-18-18, 04:25 PM
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Very, very cool. Nice work! Looks way better than the usual quill -> 1-1/8” adaptors and nice to have a bit of added front end stiffness. Your Trek looks like a blast. I could see using one in silver on a build that’s been bouncing around in my mind for a while. I’ll have to keep an eye out, glad you started a separate thread otherwise I would have probably missed this.
05-19-18, 01:20 AM
#19
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Thanks to a Marinoni that I picked up a few months ago, I now have a different quill stem adapter setup that allows me to make it look as seamless as possible. It has a -17° rise for that extra slammed cool-guy look. 
And all I had to do was add a beer can shim to get it to work properly (it worked mostly upon initial assembly)!
Bike is the recently acquired '87 Prologue, now with a 7900 FD (pictured is a 7410 FD) that shifts perfectly and doesn't chuck chains over chain rings (compatibility is an amazing thing!). I will echo the sentiment--as I have for a long while now--that doing a stem conversion gives an immediate "sure" feeling up front. Solid, yet never harsh. Love the look, too. Also: typically lighter. I dropped 160g(!) out of my front end with this conversion, bringing the total ready-to-ride weight down to 20 lb 5.5 oz.
And all I had to do was add a beer can shim to get it to work properly (it worked mostly upon initial assembly)! Bike is the recently acquired '87 Prologue, now with a 7900 FD (pictured is a 7410 FD) that shifts perfectly and doesn't chuck chains over chain rings (compatibility is an amazing thing!). I will echo the sentiment--as I have for a long while now--that doing a stem conversion gives an immediate "sure" feeling up front. Solid, yet never harsh. Love the look, too. Also: typically lighter. I dropped 160g(!) out of my front end with this conversion, bringing the total ready-to-ride weight down to 20 lb 5.5 oz.
05-19-18, 09:09 PM
#21
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Thread Starter
Originally Posted by AdventureManCO
Okay! After reading through this again, I do have some additional questions -
1. I'm assuming the cartridge bearings are replaceable - where can one find drop-in replacements?
2. Are you seeing any additional wear, especially on the top bearing, from having the torque/load of the downward force on the handlebars and stem transfer to the bearing? The way my brain is processing it...on a normal quill stem, the load from body weight follows this path: handlebars --> stem --> steerer (usually steel) --> headset. On your design, it is handlebars --> stem ---> upper headset cap. Just curious. I can see how it can be immensely more stable and stiff, but my brain keeps thinking about that 'push down' force directly against the top headset cap.
3. Is the bolt steel, and the wedge aluminum?
4. Any info on country of origin?
Thanks!
1. I'm assuming the cartridge bearings are replaceable - where can one find drop-in replacements?
2. Are you seeing any additional wear, especially on the top bearing, from having the torque/load of the downward force on the handlebars and stem transfer to the bearing? The way my brain is processing it...on a normal quill stem, the load from body weight follows this path: handlebars --> stem --> steerer (usually steel) --> headset. On your design, it is handlebars --> stem ---> upper headset cap. Just curious. I can see how it can be immensely more stable and stiff, but my brain keeps thinking about that 'push down' force directly against the top headset cap.
3. Is the bolt steel, and the wedge aluminum?
4. Any info on country of origin?
Thanks!
2. On my design, the load from the stem is shared between the upper bearing and the steerer. Remember that there is still a quill going down inside the steerer tube just like a typical threaded headset and stem. 'Real' threadless headsets do load the upper bearing just like you describe, though, and those don't seem to be grinding through upper bearings so I don't expect to, and have not seen for the record, any unusual upper bearing wear.
3. Bolt and wedge are both steel with black zinc plating. Not worth risking safety for some weight savings here. Nearly everything else is anodized 6061-T6 aluminum save for the dust seals (Buna-N), top cap plug (not shown, EPDM), top cap washer (304 SS), and bearings (52100 steel with Buna-N seals).
4. Parts are sourced from a variety of trusted vendors in China. Assembled in USA.
05-19-18, 09:12 PM
#22
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Thread Starter
Originally Posted by RiddleOfSteel
Thanks to a Marinoni that I picked up a few months ago, I now have a different quill stem adapter setup that allows me to make it look as seamless as possible. It has a -17° rise for that extra slammed cool-guy look. And all I had to do was add a beer can shim to get it to work properly (it worked mostly upon initial assembly)!
Bike is the recently acquired '87 Prologue, now with a 7900 FD (pictured is a 7410 FD) that shifts perfectly and doesn't chuck chains over chain rings (compatibility is an amazing thing!). I will echo the sentiment--as I have for a long while now--that doing a stem conversion gives an immediate "sure" feeling up front. Solid, yet never harsh. Love the look, too. Also: typically lighter. I dropped 160g(!) out of my front end with this conversion, bringing the total ready-to-ride weight down to 20 lb 5.5 oz.
And all I had to do was add a beer can shim to get it to work properly (it worked mostly upon initial assembly)! Bike is the recently acquired '87 Prologue, now with a 7900 FD (pictured is a 7410 FD) that shifts perfectly and doesn't chuck chains over chain rings (compatibility is an amazing thing!). I will echo the sentiment--as I have for a long while now--that doing a stem conversion gives an immediate "sure" feeling up front. Solid, yet never harsh. Love the look, too. Also: typically lighter. I dropped 160g(!) out of my front end with this conversion, bringing the total ready-to-ride weight down to 20 lb 5.5 oz.
05-19-18, 09:14 PM
#23
Senior Member
Thread Starter
Originally Posted by Sir_Name
Very, very cool. Nice work! Looks way better than the usual quill -> 1-1/8” adaptors and nice to have a bit of added front end stiffness. Your Trek looks like a blast. I could see using one in silver on a build that’s been bouncing around in my mind for a while. I’ll have to keep an eye out, glad you started a separate thread otherwise I would have probably missed this.
Originally Posted by exmechanic89
Very nice work, OP.
05-19-18, 10:27 PM
#24
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Originally Posted by joejack951
That's a beauty of a frameset! It's screaming for one of these conversion headsets. Think of all the weight you'd save ditching that locknut and beer can shim. And you'd be that much more slammed, too
To clarify on the beer can shim: There is a 1" quill stem adapter with fine splines. A spacer/shim (with a full length slit) slots over the adapter. The 1 1/8" stem slides over the spacer/shim and clamps down as normal. All of it is super straight forward, however, the spacer/shim+adapter diameter ended up being a touch too small for this stem's clamp. The stem could have been made "too big" with regard to tolerances, but whatever, there I was needing a solution. Just needed a touch more diameter. I cut up a section of a 12 oz. can of Bale Breaker's Bottom Cutter Imperial IPA (pour it into a glass to properly taste it, if you ever get the chance
) and used it to shim the adapter. It added not even a gram of weight while solving the problem. I am a happy camper. For fun, the Modolo quill stem weighed a whopping 359g. No wonder I could knock 160g total out of the "old" stem/bar combo.
05-24-18, 01:54 AM
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Holy crap, this unit is slick AF. I think I've daydreamed about something very similar, but you made it happen.
Mad props.
Mad props.
