Crown race not sitting flush

Discuss light weight issues concerning road bikes & parts.
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tinchy
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Joined: Sun Feb 22, 2009 9:53 pm

by tinchy

OK.
I just cant understand why a 2011 CAAD10 forks crown race wont easily fit what I believe is the 2012 CAAD10 fork. Seems odd that this much effort is needed.

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tinchy
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by tinchy

Sorry for excessive posting but would like to learn about what I will propose the mechanic does to it...

what exactly is meant by 'splitting the crown race''?

by Weenie


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rmerka
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by rmerka

tinchy wrote:what exactly is meant by 'splitting the crown race''?


A single cut through the race

Image

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tinchy
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by tinchy

Ah ok, therefore allowing for a little extra give. I guess this is relatively common practice - it wont have any knock on effect with the cartridge bearing above now that the race is slightly larger diameter?

jooo
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by jooo

Just use a vernier caliper and figure out where the problem really is...

Valbrona
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by Valbrona

I am guessing the people in the factory in China or Taiwan would not have got a Cannondale fork wrong. Instead, I am guessing the kid in the shop hasn't fitted many crown races. Light crown race fitting tools are no good; you need a heavier one, a light smear of grease and more welly. The lightest of touches with sandpaper might also be required depending on how it measures up.

Can't believe that anyone would suggest you cut through a crown bearing race.

goodboyr
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Location: Canada

by goodboyr

My point is that even with the right tool ( and I've seen many shops use a screwdriver and a hammer) there is a high probability of distorting or damaging this part that costs about 10$. My guess is that the removal distorted the inner diameter and caused this. Just get a new one that matches the fork.

jooo
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Joined: Wed Feb 02, 2011 3:48 am

by jooo

Valbrona wrote:Can't believe that anyone would suggest you cut through a crown bearing race.

:| You realise that split crown races come as a standard part for a lot of headsets right?

mattr
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Location: The Grim North.

by mattr

And that it's not actually a bearing "race". Just a support.

FWIW, I reckon it's likely to be a mismatch between the chamfer on the inner diameter of the headset and the radius on the fork.
Running a dremel round the headset to increase the size of the chamfer may be an option. It's something we have problems with in other industries. You can make nice sharp precise corners in metal (and it's cheap to do) carbon and plastic prefers nice rounded corners,which means occasionally the metal bits don't seat properly.

You must make sure that the two locating faces are undamaged tho.

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MajorMantra
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by MajorMantra

jooo wrote:
Valbrona wrote:Can't believe that anyone would suggest you cut through a crown bearing race.

:| You realise that split crown races come as a standard part for a lot of headsets right?


+1. And also +1 to the "it's not a bearing race". You realise that the bearings don't actually roll on the crown race Valbrona? We aren't talking about loose ball headsets.

There's nothing remotely unsafe or unusual about a split crown race. Any future carbon bikes I build myself will have one, and I will split them myself if they don't come pre-split.

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tinchy
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Joined: Sun Feb 22, 2009 9:53 pm

by tinchy

OK, so took the fork to another LBS today.

They had the same issue as previous shop, could not get it on completely snug even with a good whack.

They lightly used a bit of wet/dry paper and it now sits pretty close to the fork crown, maybe a mm above at max. They said that without a proper facing tool for the diameter of this fork it wont sit completely flush with the fork crown.

So Im just going to leave it at that - the race is sitting pretty close to fork crown, max 1mm gap is equal all the way around and there is no issue with steering etc.

Thanks for the help nonetheless!

em3
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by em3

..."pretty close" is not good enough. Why not just try a different race or simply split the one u have? EM3
______________

goodboyr
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Location: Canada

by goodboyr

Amazing. Like I said.....its a 10$ part!

mattr
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Location: The Grim North.

by mattr

It's not distortion causing it to not seat. Or it would be blindingly obvious. And it wouldn't be level either.
I still think the chamfer is too large, maybe 2mm radius, and you've got a 1mm chamfer.
But without a picture, can't confirm.

And if there is a gap, you'll eventually damage either the fork or the head set. Or both.

by Weenie


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tinchy
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Joined: Sun Feb 22, 2009 9:53 pm

by tinchy

But surely a new race is going to be exactly the same size?

This is the crown race I need I presume... http://www.reveloutdoors.co.uk/Cannondale-CAAD10,-Supersix-EVO-Crown-Race,-KP156/accessorydetail/3-39953

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