Threaded to threadless

[motiheal]

Hi everyone. I'd like to put a threadless carbon fork to replace my threaded 2000 Giant TCR2R carbon aero fork. I am old-school and need to know some things. If both are 1 1/8, do I just get the same steerer tube length (or longer-- I know they can be cut), then is there a different kind of fork crown? Or can I use the threaded one I have, put the spacers on top, and then the stem serves as the hold-down?

Great website-- it's helped me a lot. I will summarize the bike for everyone when finished.

[DaveS]

Carbon forks normally have one steerer length that can be cut down. The fork must be compatible with your headset. These days, most bikes use an internal headset and the steerer will have a 45 degree taper at the crown, to match the internal headset bearing. If there is no 45 degree taper, then the fork would work with a conventional external headset, or an internal headset, with the addition of a 45 degree crown race.

Try a search on YouTube, surely there are some videos on the topic.

[AJS914]

It's expense to swap out a fork and headset. I wouldn't do it unless you really have a need. Why do it? What is the goal?

There are adapters which allow you to use threadless stems. Like this:

https://www.amazon.com/Origin8-Quill-Ad ... B00R6S76TC

[joejack951]

Are you sure the current fork is 1 1/8”? 1” threaded is far more common, especially for road bikes.

[CrankyCarbon]

One of my 1997ish bikes I converted to a threadless setup. It has a 1inch Campy Record threaded headset.
edit: my other bike the frame was replaced and came with a 1-1/8 threadless setup.

With a threadless setup the stem (plus spacers) pushes down on the headset top cap.
With an old style headset you maintain the "lock" by the threaded top lock nut and top bearing race. I simply got 2 adapters so I could run 1-1/8" stems and newer 31.8 handlebars.

If you plan on going with a new fork may I recommend a LBS as they'll have the tools to make sure the seats are flat for the new fork crown, etc and give you a good initial setup.

If you google "bicycle headset parts" you can see schematic breakdowns of the two systems.

[motiheal]

It's expense to swap out a fork and headset. I wouldn't do it unless you really have a need. Why do it? What is the goal?

There are adapters which allow you to use threadless stems. Like this:

https://www.amazon.com/Origin8-Quill-Ad ... B00R6S76TC

I've got a threadless adapter on it, but with the aero fork and adapter, this weighs over 700g. If I fit an Easton SL, I am saving a pound-- for around 80 dollars!

[motiheal]

Thanks everybody. The system I have is 1 1/8 (an early Giant TCR). I am saving quite a number of grams with this change, and I'm 5'9, 150, so I can handle a light fork. I want to climb better. The LBS sounds like my option (although I like doing my own work). Thanks again!

[CrankyCarbon]

Thanks everybody. The system I have is 1 1/8 (an early Giant TCR). I am saving quite a number of grams with this change, and I'm 5'9, 150, so I can handle a light fork. I want to climb better. The LBS sounds like my option (although I like doing my own work). Thanks again!

The main advantage you'll have is that you'll be open to modern 31.8mm handlebars.

I upgraded to get newer, lighter aero handlebars from my 26.0 or 26.4 Cinelli Ergo bars and Cinelli XA stems.
My original aheadset stem on my one bike allowed me to use my Cinelli Ergo bars.
But all the new fancy, aero alloy, carbon etc need 31.8mm stem. So I made the changes. I'm glad I did too as I think this is your main advantage.
The hollow alloy, carbon or carbon/alloy stems seem much stiffer too.

[joejack951]

Thanks everybody. The system I have is 1 1/8 (an early Giant TCR). I am saving quite a number of grams with this change, and I'm 5'9, 150, so I can handle a light fork. I want to climb better. The LBS sounds like my option (although I like doing my own work). Thanks again!

If you are even a reasonably competent mechanical guy, you can handle swapping a headset and install a new fork. There are no specialized tools you need for the job, so long as you are ok piecing some things together to substitute for the more specialized, and pricey, bike tools.

[joejack951]

The main advantage you'll have is that you'll be open to modern 31.8mm handlebars.

I upgraded to get newer, lighter aero handlebars from my 26.0 or 26.4 Cinelli Ergo bars and Cinelli XA stems.
My original aheadset stem on my one bike allowed me to use my Cinelli Ergo bars.
But all the new fancy, aero alloy, carbon etc need 31.8mm stem. So I made the changes. I'm glad I did too as I think this is your main advantage.
The hollow alloy, carbon or carbon/alloy stems seem much stiffer too.

Yup, I went so far as to design my own conversion headset to allow use of threadless stems while retaining the original threaded fork. Two examples of bikes I've built with the headset:

[schlafen]

The main advantage you'll have is that you'll be open to modern 31.8mm handlebars.

I upgraded to get newer, lighter aero handlebars from my 26.0 or 26.4 Cinelli Ergo bars and Cinelli XA stems.
My original aheadset stem on my one bike allowed me to use my Cinelli Ergo bars.
But all the new fancy, aero alloy, carbon etc need 31.8mm stem. So I made the changes. I'm glad I did too as I think this is your main advantage.
The hollow alloy, carbon or carbon/alloy stems seem much stiffer too.

Yup, I went so far as to design my own conversion headset to allow use of threadless stems while retaining the original threaded fork. Two examples of bikes I've built with the headset:

Any details on the headset setup?

Sent from my SM-G960F using Tapatalk

[joejack951]

Any details on the headset setup?

Sure!

Here's the headset by itself:



Cross section:



It's sort of a marriage between a threaded headset and a threadless adapter. The main design detail is that I've integrated the upper race into the quill/threadless portion by bonding two components together. The entire quill and upper race turn together when preloading the headset bearings and then the adjustment is locked out simultaneously with the quill locking into the steerer tube. Thus, no ugly lock nut and its unnecessary stack height plus you only need a 6mm hex key to adjust the preload.

The threadless portion is designed to allow trimming to whichever height you'd like, down to 38mm or full length at 90mm. I made custom spacers with an internal o-ring to keep them from rattling since the stem isn't applying any compression force. Sealed bearings and dust seals top and bottom to round things out.

Works with any 1"-24 threaded fork and headtube with ISO dimensions. JIS can be accommodated with minor adjustments.

[AJS914]

I've got a threadless adapter on it, but with the aero fork and adapter, this weighs over 700g. If I fit an Easton SL, I am saving a pound-- for around 80 dollars!

$80 sounds like a used fork or a fake on ebay or aliexpress. I wouldn't mess with anything other than a new fork.

[schlafen]

Any details on the headset setup?

Sure!

Here's the headset by itself:



Cross section:



It's sort of a marriage between a threaded headset and a threadless adapter. The main design detail is that I've integrated the upper race into the quill/threadless portion by bonding two components together. The entire quill and upper race turn together when preloading the headset bearings and then the adjustment is locked out simultaneously with the quill locking into the steerer tube. Thus, no ugly lock nut and its unnecessary stack height plus you only need a 6mm hex key to adjust the preload.

The threadless portion is designed to allow trimming to whichever height you'd like, down to 38mm or full length at 90mm. I made custom spacers with an internal o-ring to keep them from rattling since the stem isn't applying any compression force. Sealed bearings and dust seals top and bottom to round things out.

Works with any 1"-24 threaded fork and headtube with ISO dimensions. JIS can be accommodated with minor adjustments.

Does it flex? looks like there are quite a few layers on the top section.

Sent from my SM-G960F using Tapatalk

[joejack951]

Does it flex? looks like there are quite a few layers on the top section.

Having ridden bikes with quill stems, standard threadless adapters, true threadless stems, and this conversion headset, my feeling is that the latter two are nearly identical in stiffness. The bonded upper race contributes a lot of support to the quill in this design, utilizing the upper bearing just like a real threadless system, something which standard quill stems and threadless adapters both lack.

I believe what you are referring to as 'layers' are the tangent lines in my CAD model. Perhaps this simpler view of the upper race (left) and quill (right) will help clear things up. The interior of the quill has a few 'steps' to it which accommodate maintaining a consistent wall thickness while the outer diameter varies (traveling along its lengths from left to right, from 22.2mm at steerer tube insertion, to ~25.5mm where it is bonded with the upper race, to 31.8mm at the stem clamp zone). Note that the diameter where the bond occurs is just slightly larger in diameter than the 1" threaded steerer tube that gets inserted/threaded into the upper race. The upper race's outer diameter is 31.8mm as well which allows a stem to be installed all the way down near the upper bearing.