# Crown race won't fit on carbon steerer



## Kneedragon (Jul 27, 2010)

I'm in the initial stages of a build and I can't seem to get the crown race onto the carbon steerer.

The fork is all carbon, with a tapered steerer (1 1/8" to 1 1/4"). I've measured the diameter of the bottom of the steerer to be 33.6mm and the inside diameter of the crown race to be 32.9mm. This is a 0.7mm, which could be quite significant.

So what should I do? So far I see my options being:

1) Smash the crown race on anyways and see what happens. Maybe heat the crown race first?
2) Face the inside of the crown race to get it closer to 33.6mm.
3) Buy a new headset and hope that the new crown race is closer to 33.6mm.

Any help here is much appreciated.


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## bikerjulio (Jan 19, 2010)

Cane Creek have the standard 1 1/4" crown race at 33.06 +/- 0.03mm, putting both your measurements outside the limits.

http://www.canecreek.com/manuals/Headset_Identification_and_SpecificationGuide.pdf

Not much help I know.

Some carbon forks (see link) may not use a crown race at all. The carbon bears directly on the inner race of the lower bearing, just as the crown race would.


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## FTR (Sep 20, 2006)

I am going to guess it is a pressfit crown race and if so it is designed to be basically hammered on.
If it is the headset that came with a Chinese frame then it most definitely is pressfit.


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## NEO Dan (Jun 10, 2010)

What is the maker of the frame and fork and have you contacted them? I would guess they would exchange them...


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## TimV (Mar 20, 2007)

The correct crown race diameter for a 1 1/4" headset is 33.0mm. The fork you have is slightly over sized. What kind of fork is it? I would contact the manufacturer and see if they can offer an exchange. 

The next option would be to mill (or 'face') the fork down to 33.0. This is a little tricky because if you remove too much material, you're SOL.

Whatever you do, DO NOT try to hammer the crown race onto the fork as is. That much of a dimensional difference (0.7mm) is too much for an interference fit. You will damage both parts in the process.


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## FBinNY (Jan 24, 2009)

FTR said:


> I am going to guess it is a pressfit crown race and if so it is designed to be basically hammered on.
> If it is the headset that came with a Chinese frame then it most definitely is pressfit.


The amount of interference for a press fit crown race is typically .05mm, so if the OP is measuring accurately, there's no way the race could be pressed on. 

I suspect that he has a 33mm (nominal) race which should measure 32.95-33.00. If the fork as truly that much bigger there's something wrong with it, unless it came with it's own race.

The OP might have the option of using a split "crown race" since on most sealed headsets the crown race isn't one at all, but only a centering cone for inner race of the lower bearing.


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## FTR (Sep 20, 2006)

TimV said:


> The correct crown race diameter for a 1 1/4" headset is 33.0mm. The fork you have is slightly over sized. What kind of fork is it? I would contact the manufacturer and see if they can offer an exchange.
> 
> The next option would be to mill (or 'face') the fork down to 33.0. This is a little tricky because if you remove too much material, you're SOL.
> 
> Whatever you do, DO NOT try to hammer the crown race onto the fork as is. That much of a dimensional difference (0.7mm) is too much for an interference fit. You will damage both parts in the process.


No way would I be "milling" a CF steerer.
Also you are assuming he measured everything perfectly.
You can easily get a variance if you dont.


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## Al1943 (Jun 23, 2003)

My Colnago 1 1/8 all carbon fork had to be "faced" with a special tool before the Chris King race could be installed. No problems with the "facing".


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## NEO Dan (Jun 10, 2010)

Al1943 said:


> My Colnago 1 1/8 all carbon fork had to be "faced" with a special tool before the Chris King race could be installed. No problems with the "facing".


Was the carbon coated to protect it from moisture absorption?


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## Al1943 (Jun 23, 2003)

NEO Dan said:


> Was the carbon coated to protect it from moisture absorption?


I don't know, you'd have to ask Ernesto.


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## TimV (Mar 20, 2007)

FTR said:


> No way would I be "milling" a CF steerer.
> Also you are assuming he measured everything perfectly.
> You can easily get a variance if you dont.


Just because you are afraid to do something, doesn't mean it can't be done. Assuming his measurements are close (and yes, I did assume that :roll eyes: ), we're only talking about 0.010" to 0.015" of material removal. That's not very much considering the material thickness in that part of the fork probably exceeds 0.250".


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## FTR (Sep 20, 2006)

TimV said:


> Just because you are afraid to do something, doesn't mean it can't be done. Assuming his measurements are close (and yes, I did assume that :roll eyes: ), we're only talking about 0.010" to 0.015" of material removal. That's not very much considering the material thickness in that part of the fork probably exceeds 0.250".


Or you could just use the pressfit crown race how it was meant to be used.
And I am not even going to assume that he knows the difference between .7mm and .07mm.


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## NEO Dan (Jun 10, 2010)

Al1943 said:


> I don't know, you'd have to ask Ernesto.


Yeah let me get right on that, I think I'll send an e-mail to Ernesto...

But seriously, if you had a spot of bare carbon exposed on your bike due to a tire rub or something of that nature and it failed you'd be SOL in the warranty department. The interesting thing about the crown is that moisture/grease/grit/solvent can accumulate there and not easily be removed if at all while assembled. Washing your bike or getting caught out in the rain are not uncommon. Carbon needs to be sealed to prevent contamination of the layup, you could easily drop the fork and see if it's been sealed up. 

Incidentally I just bought and sent back an Easton fork that had been sanded on at the crown. Easton service e-mailed me a shipping tag within minutes of my calling to ask if they were OK with bare carbon at the crown.


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## Kontact (Apr 1, 2011)

NEO Dan said:


> Yeah let me get right on that, I think I'll send an e-mail to Ernesto...
> 
> But seriously, if you had a spot of bare carbon exposed on your bike due to a tire rub or something of that nature and it failed you'd be SOL in the warranty department. The interesting thing about the crown is that moisture/grease/grit/solvent can accumulate there and not easily be removed if at all while assembled. Washing your bike or getting caught out in the rain are not uncommon. Carbon needs to be sealed to prevent contamination of the layup, you could easily drop the fork and see if it's been sealed up.
> 
> Incidentally I just bought and sent back an Easton fork that had been sanded on at the crown. Easton service e-mailed me a shipping tag within minutes of my calling to ask if they were OK with bare carbon at the crown.


I have a bare carbon Calfee. We've sold multiple bare Parlees and Calfees. Carbon brake tracks are bare. They don't need paint or coatings, because carbon fiber composites consist of nothing more than solid graphite fibers in epoxy resin. There is nothing there that can absorb liquids.

Your post wins the prize for craziest carbon fiber misinformation of the year. Congrats.


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## NEO Dan (Jun 10, 2010)

*typo*



Kontact said:


> I have a bare carbon Calfee. We've sold multiple bare Parlees and Calfees. Carbon brake tracks are bare. They don't need paint or coatings, because carbon fiber composites consist of nothing more than solid graphite fibers in epoxy resin. There is nothing there that can absorb liquids.
> 
> Your post wins the prize for craziest carbon fiber misinformation of the year. Congrats.


OK then answer this question; if you get the frame wet for more than a moment and wipe it off does it look completely dry or like it was wet?


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## NEO Dan (Jun 10, 2010)

Exposure to UV is also bad for some resins used in the manufacture of carbon fiber parts if you care to look around...


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## FTR (Sep 20, 2006)

NEO Dan said:


> Exposure to UV is also bad for carbon if you care to look around...


Yes it will assplode!!!
And melt in the rain.


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## NEO Dan (Jun 10, 2010)

Sorry FTR, :thumbsup:
I understated the position, now corrected above... : )

Steel is real, LOL

Real heavy...


I ride carbon - really


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## FTR (Sep 20, 2006)

Me too, and ti.
One for probably a lot longer than the other before it needs replacing.


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## Kontact (Apr 1, 2011)

NEO Dan said:


> OK then answer this question; if you get the frame wet for more than a moment and wipe it off does it look completely dry or like it was wet?


The surface is fiberous and water sits on the surface differently than something slick. But it isn't absorbing anything, it just has more surface area.

Micarta is a composite made from fabrics and paper. The linen and canvas micartas used for knife handles will absorb some water into the fibers, but it doesn't hurt the epoxy structure. 

By contrast, nylon actually does break down chemically in the presence of water, but that's still not a problem that anyone worries about.


UV can be a problem with everything - including paint. But UV doesn't damage the carbon fibers, and carbon composites are opaque, so how much damage could UV do to a composite as a whole?


Now that I've answered your questions, how about sharing a source for this knowledge nugget for absorbent carbon fiber problems?


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## gamara (May 20, 2002)

Not to detract from the OP question but people have some very weird concepts about carbon. To some people its indestructible & to others its as fragile as glass. If people actually watch how a carbon frame is constructed, you would see that there is quite a bit of sanding involved. People with carbon tubular rims use solvents & glue on bare carbon all the time. So I don't think anything gets "absorbed".

What people get confused about is when they think that something like a scratch in the carbon clear coat will lead to failure. Carbon failure is usually due to stress risers acting on an area over time. This could be anything from impacts to over tightening something.

As for the OP, there was the recommendation of milling the area down. If the clear coat is too thick, there is nothing wrong with removing just enough of it to help ease installation.


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## Bill2 (Oct 14, 2007)

I had the same problem. Used very fine sand paper and spent an hour or two delicately removing the excess material from the circumference of the 7mm high shoulder at the base of the steerer. Pressed the crown fork race on and it's been working great for the past couple of years.


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## NEO Dan (Jun 10, 2010)

Kontact said:


> Now that I've answered your questions, how about sharing a source for this knowledge nugget for absorbent carbon fiber problems?


It's simple; carbon should not be exposed to contaminants if possible. Giving it a protective coating is normal and correct practice. I do have some practical experience with raw carbon fiber, you reminded me of my 940CF D2 this thing has shed many little pieces of it's surface over the years...
Getting carbon fiber splinters in your fingers sucks


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## Kneedragon (Jul 27, 2010)

Thanks for the replies and insight everyone.

Here's the answers to a few questions:

- Bike is a BMC Team Machine SLR01.
- Crown race is press fit
- There is no clear coat on the steerer, so if I were to sand it down, I would be sanding the bare carbon.

Any objections to reaming the inside of the crown race? I can get a new one from FSA for $16 shipped if I accidently take out too much material.


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## TimV (Mar 20, 2007)

Kneedragon said:


> Any objections to reaming the inside of the crown race? I can get a new one from FSA for $16 shipped if I accidently take out too much material.


How do you plan on doing this? Do you have a lathe? The reason I ask is that if you just plan on using a file or sandpaper, you going to be there for a while. Also, the result will be neither very pretty nor round.


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## NEO Dan (Jun 10, 2010)

BMC are good to there customers, you'll need to go through who you bought the frame/bike from though. 
As mentioned before is the steerer crown that oversize? .7mm oversize is huge for a raw carbon part made in a mold. Maybe it heard you talking bad about it and it swelled up... 
Seriously though if it's that big and you drove the race on as is it would stretch and the bearing would not fit on the race properly. I ride BMC too btw :thumbsup:


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## Kneedragon (Jul 27, 2010)

TimV said:


> How do you plan on doing this? Do you have a lathe? The reason I ask is that if you just plan on using a file or sandpaper, you going to be there for a while. Also, the result will be neither very pretty nor round.


Park Tool makes a reaming tool that may be able to do it. Although their tolerances are up to 33mm, so it might not help very much. I may look for other reaming tools, but not sure if I'll be able to find anything with such tight tolerances.

Other option would be to file it or use sandpaper. As long as it fits snug on the steerer, it wouldn't have to look all that great since it will all be hidden in the head tube.


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## Kneedragon (Jul 27, 2010)

NEO Dan said:


> BMC are good to there customers, you'll need to go through who you bought the frame/bike from though.
> As mentioned before is the steerer crown that oversize? .7mm oversize is huge for a raw carbon part made in a mold. Maybe it heard you talking bad about it and it swelled up...
> Seriously though if it's that big and you drove the race on as is it would stretch and the bearing would not fit on the race properly. I ride BMC too btw :thumbsup:


I bought the frame through eBay, so going through BMC may not be an option.

The steerer is quite oversize, and its noticeable when you slide the crown race on, it immediately gets stuck as soon as the steerer diameter increases.

Good point about stretching the crown race though. I don't think forcing it on was ever a real option, but I figured I would just throw it out there.


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## TimV (Mar 20, 2007)

Kneedragon said:


> Other option would be to file it or use sandpaper. As long as it fits snug on the steerer, it wouldn't have to look all that great since it will all be hidden in the head tube.


First of all, the crown race is hardened steel. Removing .70mm of material with sandpaper by hand will take hours.

Secondly, the problem with doing that is not that is won't look nice. The problem is that the ID of the crown race will no longer be round nor concentric to the bearing race. IF you are able to get the race to fit on the fork (and that's a big IF), it will be deformed which could result in uneven stress on the fork and premature bearing wear.



Kneedragon said:


> Good point about stretching the crown race though. I don't think forcing it on was ever a real option, but I figured I would just throw it out there.


It's not an option. If the dimensional difference really is .70mm, you will either damage the fork or crack the crown race.

At this point, I would either call BMC or take it to your LBS.


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## NEO Dan (Jun 10, 2010)

I know you must be eager to ride, but you should let the dealer/BMC take care of this. Seems like your fork may have skipped a step in the production process; maybe it was meant to be machined to final size that's the only reason that seems logical to me. I'd be boxing up the fork, race, and bearing and calling for a shipping tag.


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## NEO Dan (Jun 10, 2010)

TimV said:


> First of all, the crown race is hardened steel. Removing .7mm of material with sandpaper by hand will take hours.


The bearing race is probably steel, but the crown race is what the bearing sits on and that's aluminum.


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## NEO Dan (Jun 10, 2010)

Kneedragon said:


> I bought the frame through eBay, so going through BMC may not be an option.


Wow bummer, this is manufacturing defect though and should be covered if not modified. 



Kneedragon said:


> The steerer is quite oversize, and its noticeable when you slide the crown race on, it immediately gets stuck as soon as the steerer diameter increases.


will the bearing physically fit over the steerer crown?


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## NEO Dan (Jun 10, 2010)

It also seems to me that whoever sold this to you should be able to provide you with an original proof of purchase and dealer contact info, if not contact PayPal and tell them you were sold defective goods and the seller won't help you by providing acceptable proof of purchase info so you may establish a warranty claim. eBay/PayPal should have your back on this.


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## NEO Dan (Jun 10, 2010)

What's the ID of the crown race you have? A 1 1/8" crown race is ~30mm ID, is it possible you were sent the wrong headset parts?


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## Kneedragon (Jul 27, 2010)

The lower bearing physically fits over the steerer just fine. But then it should, because the ID of it should be 1-1.5mm less to make up for the inner part of the crown race.

It is definitely the correct crown race. And it's measurements also confirm it. (It is 1 1/4")

I've contacted BMC to see if they can help. I'm not really expecting them to do much (due to the situation), so maybe my other option is to lightly sand the steerer.


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## TimV (Mar 20, 2007)

Kneedragon said:


> I've contacted BMC to see if they can help. I'm not really expecting them to do much (due to the situation), so maybe my other option is to *lightly sand the steerer*.


Again, this will take a long time and the result will be sub-par. Your LBS will have a tool that is specifically designed to do this job. It looks like this:

<img src="http://s.wiggle.co.uk/images/park%20crc1.jpg?w=350&h=350&a=7"/>

It's worth (both in time and end result) the $20 (or whatever) they charge to have the job done properly with the correct tooling.


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## ultimobici (Jul 16, 2005)

Kneedragon said:


> The lower bearing physically fits over the steerer just fine. But then it should, because the ID of it should be 1-1.5mm less to make up for the inner part of the crown race.
> 
> It is definitely the correct crown race. And it's measurements also confirm it. (It is 1 1/4")
> 
> I've contacted BMC to see if they can help. I'm not really expecting them to do much (due to the situation), so maybe my other option is to lightly sand the steerer.


Are you sure the forks aren't designed to be used without the race? Many modern headsets the use cartridge bearings so don't need a metal seat. The headset provided may be complete from its original manufacturer as that is the only way they sell it, irrespective of if you are an end user or manufacturer. 

If possible post a picture of the crown as it'll be pretty obvious to those of us who work on bikes day in day out.


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## bikerjulio (Jan 19, 2010)

don't know if this is any help, but here's a picture I found










the BMC site for tech manuals appears to be farked. no matter what I do, all I get is the Time Machine manual.


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## velodog (Sep 26, 2007)

Bring the bike, fork and headset to a good shop and let them install it.
A good shop will have all the tools to do the job properly and if there is something out of the ordinary they will know how to deal with it. Once the headset has been installed you will be able to do all future maintenance yourself.

It can be dangerous taking advice from a bunch of responses on the interwebs, you may take advice from the knucklehead while passing on the advice of the real mechanic.


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## NEO Dan (Jun 10, 2010)

I found something interesting on youtube, in 2009 when the SLR01 came out the spec for the lower crown was 1.4" according to BMC, and the BMC catalog spec is 1.5" for the lower headset. Looks like you have the wrong headset parts for the bottom end. I'm sure BMC knows what parts you need. If you've not heard from them yet I'd give them a call on Monday.


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## Kneedragon (Jul 27, 2010)

ultimobici said:


> Are you sure the forks aren't designed to be used without the race? Many modern headsets the use cartridge bearings so don't need a metal seat. The headset provided may be complete from its original manufacturer as that is the only way they sell it, irrespective of if you are an end user or manufacturer.
> 
> If possible post a picture of the crown as it'll be pretty obvious to those of us who work on bikes day in day out.


Here is a pic of the fork crown, and how far the crown race goes before it stops:


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## NEO Dan (Jun 10, 2010)

That crown looks perfect! Also looks like you will be the first to ride this fork. If you don't get an answer on the tech line when you call it will kick you back out to the main menu and you can select sales, they tend to answer. Did you know there is a BMC forum here? Just scroll down on the main page.


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## bikerjulio (Jan 19, 2010)

OP you are sure about the 33.6mm dimension? Not 33.06?

33.6 is significantly over spec.

If really 33.6, maybe BMC will take pity & offer a replacement.


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## NEO Dan (Jun 10, 2010)

Looking at the race it has marks like it's been pulled with a puller, I wonder if it got squished and now it's out of round a bit?


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## Kneedragon (Jul 27, 2010)

Ok, well this is embarassing.... I may have measured it incorrectly the first time, meaning that I probably didn't have the tool completely level. I am 100% sure it read 33.61 the first time I measured it, but after subsequent tries it appears to be closer to 33.05.

I will be taking it to the LBS to have them put it on anyways, so it should be fine. I will provide an update once I've got it sorted out.

Thank you to all who provided advice!


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## NEO Dan (Jun 10, 2010)

WOW :thumbsup: :thumbsup: :thumbsup: 

Take fork and race to Lowes or HomeDepot plumbing dept. They sell 2' sections of PVC.

Select either 1.25" or 1.5" PVC, whatever fits best. 
Place crown on fork then PVC 
Invert components and tap PVC against pavement until race is seated squarely at bottom of crown. 
Decide whether you are actually purchasing the PCV


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## Kneedragon (Jul 27, 2010)

Just a quick update:

The LBS got the crown race onto the fork without any issues. Everything is good now! :thumbsup:


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