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Help, fitting a THM fork into Colnago frame

Posted: Wed Feb 07, 2018 6:28 am
by Nazhemie
Hi everyone, i have a THM fork from a Cervelo R5Ca 2011 1 1/8“ – 1 3/8“ . I want the fork to fit into my Colnago Strada SL 2014 1 1/8" - 1 1/4" . I believe that the Cervelo R5Ca frame headset is Integrated while the Colnago Strada SL is Semi-Integrated headset frame which need to put the bearing Cup to install the headset and fork.
I cannot fully insert by previous lower headset bearing which is Ritchey WCS Press Fit 1 1/4 which have Internal Diameter bearing of 34mm into the THM lower fork tube which is 36mm. I tried the Cane Creek 1 3/8 36x45 bearing which have ID of 37mm. Which headset is suitable for my Colnago with THM fork?

THM Cervelo R5CA 2011 fork 1 1/8 to 1 1/4"
Upper fork tube diameter 28.6mm
Lower fork tube diameter 36mm
came along with Cane Creek 1 3/8" bearing
ID 37mm , OD 49mm

Colnago Strada SL 2014 fork 1 1/8 - 1 1/4"
Upper fork tube diameter 28.6mm
Lower fork tube diameter 33mm
Using Ritchey WCS ZS49/33 Lower bearing 1 1/4" bearing
ID 34mm, OD 45mm

Someone use a CK headset to fit the fork.
If CK headset will do the job,which one i need? Inset 3, Inset 5 or Inset 7 ?
Or there any suggestion ?
R5Ca.jpg
Specs
weightr5ca.jpg
Weight
THMr5.jpg
Details
THMCEr.jpg
CerveloTHM
Starnut.jpg
Starnut
SLr8.jpg
My Colnago Strada SL Italia stripe Tri-Color.
With Shimano Ultegra R8000.
Named it Colnago SLR8 ( Accelerate ) :P
7676 grams
NagoHead.jpg
Colnago Fork with Ritchey WCS Lower 1 1/4"

Re: Help, fitting a THM fork into Colnago frame

Posted: Wed Feb 07, 2018 9:55 am
by kdawg
You say at the top at its 1 3/8 then further down that it’s 1 1/4. I’m assuming it’s the first one and that’s why it won’t fit - it’s bigger.

I’ve seen headsets to fit a narrower steerer - but never a bigger one.

Re: Help, fitting a THM fork into Colnago frame

Posted: Wed Feb 07, 2018 10:35 am
by Nazhemie
kdawg wrote:
Wed Feb 07, 2018 9:55 am
You say at the top at its 1 3/8 then further down that it’s 1 1/4. I’m assuming it’s the first one and that’s why it won’t fit - it’s bigger.

I’ve seen headsets to fit a narrower steerer - but never a bigger one.
Upper section tube measurement for both fork is 28.6mm means 1 1/8
Only lower is different
For colnago fork is 33mm
For thm fork is 36mm
This may help
rsz_img_20180207_170056.jpg
Side to side
Left is colnago
Right is thm
rsz_img_20180207_170030.jpg
Measurements
Colnago lower headtube 48.6mm
Ritchey wcs cup 49.35mm

Re: Help, fitting a THM fork into Colnago frame

Posted: Wed Feb 07, 2018 12:08 pm
by Lelandjt
I've never seen someone get a fork into a frame that's made for a smaller fork. Your THM is 1/8" too big for the Colnago.

Re: Help, fitting a THM fork into Colnago frame

Posted: Wed Feb 07, 2018 5:33 pm
by Nazhemie
Lelandjt wrote:
Wed Feb 07, 2018 12:08 pm
I've never seen someone get a fork into a frame that's made for a smaller fork. Your THM is 1/8" too big for the Colnago.
No it can fit fine to the frame but the lower bearing is the problem..

Re: Help, fitting a THM fork into Colnago frame

Posted: Wed Feb 07, 2018 6:16 pm
by glepore
Assuming that the Colnago has a 49 mm non tapered headtube, nothing you've looked at works. The inset 5 is 49mm but it only works with 1 1/4-1 1/2 tapered. The 1 /3/8 is VERY oddball. The only other bike I know of that uses one is the Speialized Allez Smartweld which uses a 49mm semi integrated bearing for an 1 3/8 fork crown. Search for that bearing - Cane Creek might have one but they just redid their website and the bearing finder tool is gone. The only other solution would be to buy and adapter that adapts crown race of 1 1/4 fork to a 1 1/2 bearing (those headsets are common, inset 5 works) and have a machinist mill it out from 1 1/8 to 1 3/8.

viewtopic.php?t=130531

https://forums.thepaceline.net/showthread.php?t=149417

Honestly, its a holy grail type thing.

Re: Help, fitting a THM fork into Colnago frame

Posted: Thu Feb 08, 2018 10:54 am
by elfuinha
glepore wrote:
Wed Feb 07, 2018 6:16 pm
Assuming that the Colnago has a 49 mm non tapered headtube, nothing you've looked at works. The inset 5 is 49mm but it only works with 1 1/4-1 1/2 tapered. The 1 /3/8 is VERY oddball. The only other bike I know of that uses one is the Speialized Allez Smartweld which uses a 49mm semi integrated bearing for an 1 3/8 fork crown. Search for that bearing - Cane Creek might have one but they just redid their website and the bearing finder tool is gone. The only other solution would be to buy and adapter that adapts crown race of 1 1/4 fork to a 1 1/2 bearing (those headsets are common, inset 5 works) and have a machinist mill it out from 1 1/8 to 1 3/8.

viewtopic.php?t=130531

https://forums.thepaceline.net/showthread.php?t=149417

Honestly, its a holy grail type thing.
The Thm fork will need a 1 1/2 bearing.
i use a CK inset 7 on my bike with this fork.

Re: Help, fitting a THM fork into Colnago frame

Posted: Thu Feb 08, 2018 1:40 pm
by glepore
Ok, with no crown race-ie the fork has an integrated crown race ?

Re: Help, fitting a THM fork into Colnago frame

Posted: Wed Feb 14, 2018 5:30 am
by Nazhemie
elfuinha wrote:
Thu Feb 08, 2018 10:54 am
glepore wrote:
Wed Feb 07, 2018 6:16 pm
Assuming that the Colnago has a 49 mm non tapered headtube, nothing you've looked at works. The inset 5 is 49mm but it only works with 1 1/4-1 1/2 tapered. The 1 /3/8 is VERY oddball. The only other bike I know of that uses one is the Speialized Allez Smartweld which uses a 49mm semi integrated bearing for an 1 3/8 fork crown. Search for that bearing - Cane Creek might have one but they just redid their website and the bearing finder tool is gone. The only other solution would be to buy and adapter that adapts crown race of 1 1/4 fork to a 1 1/2 bearing (those headsets are common, inset 5 works) and have a machinist mill it out from 1 1/8 to 1 3/8.

viewtopic.php?t=130531

https://forums.thepaceline.net/showthread.php?t=149417

Honestly, its a holy grail type thing.
The Thm fork will need a 1 1/2 bearing.
i use a CK inset 7 on my bike with this fork.
I see, do you have some pictures of your bike with the THM fork?
Inset 7? but i cant use it because the lower is EC44.
I may use Inset 3 & 5 because of my frame lower headtube diameter are 49mm and the THM fork is 1 3/8 or i assumely think it was 1.5"

I tried CANE CREEK HEADSET ZS44/EC49 in my LBS but it wouldn't fit properly into the frame because inside the lower headtube, there were some like stopper for the lower cup to be seat on. So i need to get custom machine cut for it to fit into the frame. So i just think about finding a ZS49/40 not ZS49/30. (currently using ZS49/33)
1517223210-68.jpg
headset cut.jpg
need to cut
So i found a FSA and Da Bomb. I choosed fsa and already purchased FSA Gravity 4

brand:FSA
Content: 1 piece
Material: Aluminium, stainless steel
Surface finish: anodisized
fork steerer size: 1.5" tapered
S.H.I.S.: EC49/28.6, ZS49/40
headset type: external, semi-integrated
fsa-gravity-4-headset-schwarz-517788-en.jpg
I just get the lower headset only
DARTMOOR_Dive_Steuersatz_ZS44_28_6_I_ZS49_40_schwarz[621x610].jpg
DARTMOOR Dive Headset ZS44/28.6 I ZS49/40

Re: Help, fitting a THM fork into Colnago frame

Posted: Wed Feb 14, 2018 6:00 am
by Nazhemie
glepore wrote:
Thu Feb 08, 2018 1:40 pm
Ok, with no crown race-ie the fork has an integrated crown race ?
Yes, integrated crown race . Bearing 1 3/8 fitted half way and 1 1/2 bearing fitted fully.