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Discussion Starter · #1 ·
I thought I would come to the pros for some much needed advice. I have built up road bikes, but this is my first mtb 29er. I am building up from a 2010 GF Paragon with Fox G2 fork and have run into a slight snag with installing the fork.
Headset cups pressed in nicely. Please see the headset specs below.



The snag is with respect to seating the lower bearing race onto the top of the fork crown. Please note that the base of the steerer tube flairs slightly just above the upper fork crown. See yellow arrows for the interference:


The I.D. of the race you see directly adjacent to the slightly bulged base of the steerer will not fit over the bulged steerer O.D. without some axial force. My question is...should I exert force to press this race over the bulged steerer tube such that the bottom of the race will nest line to line to the top of the fork crown? My concern is this rather slight race will distort if pressed down over the bulge you see at the base of the steerer and therefore will affect the convex to concave interface to the lower bearing.
What are my optons? Should I seek another race from FSA? Should either the steerer OD or race ID be ground slightly to create a slip fit?

Any advice would be greatly appreciated. Many Thanks.

Frame/fork combo below:
 

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It's supposed to be a press fit, but not impossible. This would be easier to help with if you could measure the steer tube OD with a micrometer, and the headset race ID with a telescoping gauge and a micrometer, and then mention what the difference is in thousandths of an inch.
 

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Discussion Starter · #3 ·
Thank you Roadsters. I needed validation there is supposed to be a light press fit versus a slip or line-to-line fit.

The press when performed will indeed be light to push the race down flush on top of the fork crown. By eye I would say the amount of interference is scant or probably about .001" interference or so. No doubt the thin I.D. lip of the race will lightly deform to allow pushing it down all the way on the steerer tube.

As to design intent which sounds like it is...I am surprised that it is normal to have any interference because the pre-load of the headset would automatically keep the race tightly captured between the fork crown and bottom bearing without any axial movement.

Thanks again.
 

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To properly install the race without damaging it, make sure you use the correct tools. If you don't have the correct tools, take the fork and race to a good local bike shop where the race can be installed by a person who is knowledgeable about working on bikes and is properly equipped.
 

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Discussion Starter · #5 ·
Blaster1200 said:
To properly install the race without damaging it, make sure you use the correct tools. If you don't have the correct tools, take the fork and race to a good local bike shop where the race can be installed by a person who is knowledgeable about working on bikes and is properly equipped.
Quite honestly Blaster, I am a bit disappointed in the responses I gleaned here. I went out on the web and researched best practices.
Yes you can purchase a dedicated Park tool to press the crown race down but the best tip for the edification of others is:

Purchase a section of PVC pipe from Lowes for less than $3, then cut 1 ft off to use as a crown race setter. Try to cut it straight to get even contact all around the crown race. Then pound with a rubber mallet until seated. No damage to my Chris King crown race. Get 1 1/4 inch Schedule 40 PVC, which won't splinter like regular PVC

Some further comments for those technical cats:

Alternatively you can invert the fork and use the weight of the fork a slide hammer to set the race. The important thing is to drive the race orthogonal to the steerer tube, i.e. perpendicular in 2 planes. If you are anal, you can wrap the steerer tube with some electrical tape top and bottom to allow the PVC pipe to slide perfectly parallel to the steerer which will insure the pipe will not cock and the race will be seated evenly. A further tip is to apply a light film of anti seize to the base of the steerer tube prior to installing the crown race.

Hope that helps others.
 

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I agree with Blaster1200, take it to someone who knows what they are doing and has the correct tools. That fork looks pretty nasty to me, I would probably run a fork crown race cutter over it and make sure it's properly cut. That's not a tool you're going to find in the plumbing aisle at the hardware store.
 

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Discussion Starter · #7 ·
unterhausen said:
I agree with Blaster1200, take it to someone who knows what they are doing and has the correct tools. That fork looks pretty nasty to me, I would probably run a fork crown race cutter over it and make sure it's properly cut. That's not a tool you're going to find in the plumbing aisle at the hardware store.
The fork is unmolested and brand new. It looks nasty to you? In what context? If I use any cutting tool affecting either the steerer tube or crown race I.D. I will lose all interfere and there will be no press.
 

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Heat the race in near boiling water , it will seat by hand , no tools needed .
 

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here's another simple home remedy. I've been doing this for years. Just drill a hole in a 2x4 the size of the steerer tube, set it on a bucket, slide steerer with crown race through hole, grab with both hands and bang away. The soft wood will actually mould to the shape of the crown race. That 2x4 and bucket have done quite a few of them, the bucket's showing it's age though.
I always grease the base of the steerer (where the crown race will sit) to help with setting the race, but also to hopefully make it easier to remove in the future.
 

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Discussion Starter · #11 ·
trailville said:
here's another simple home remedy. I've been doing this for years. Just drill a hole in a 2x4 the size of the steerer tube, set it on a bucket, slide steerer with crown race through hole, grab with both hands and bang away. The soft wood will actually mould to the shape of the crown race. That 2x4 and bucket have done quite a few of them, the bucket's showing it's age though.
I always grease the base of the steerer (where the crown race will sit) to help with setting the race, but also to hopefully make it easier to remove in the future.
Thank you trailville. I appreciate your voice of experience. No doubt grease or anti-seize paste as recommended by some will serve the same purpose.
Thanks again for sharing your tip with us.
 

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dirtrider7 said:
I went out on the web and researched best practices.
Being that you didn't have the ingenuity to do the search in the first place, I certainly didn't think you were capable of working on a bicycle. You proved me wrong. You are ingenious...just lazy.
 

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Discussion Starter · #13 · (Edited)
Blaster,
That's two wasted posts from you. You want to go for three? Ingenious? Master's in mechanical engineering and 30 years in product development? Lazy? I thought I would come here for best practices. Since initially I didn't get much positive input including your silly comments about using the right tools and taking the frameset to a local bike shop etc...after a good laugh I then went out on the web and came back and shared the best practices I gleaned to help others and promote further discussion which is what happened. Meanwhile the good guys on this great site stepped up with some other great tips and now others have a bit better roadmap when contemplating the best way to install a crown race.
Please put me on ignore if you would. I really don't like the negativity of your posts.

Thanks again to others for the well intentioned and great advice. As a matter of practice, the least invasive practice of boiling the crown race is the most clever IMHO. I am reminded of the opposite practice of shrinking bearing sleeves to eliminate press in different applications. Great stuff. Now I should calculate the amount of dilation to the ID of the crown race due to thermal expansion by elevating its temperature by 212-72 deg F, but think I will try it instead :)
Can't go wrong with either wood or PVC for driving the race in the event of some light residual press as each are much softer than the a race which natively is very strong due to cross-section and material. Driving the race perpendicular is key of course.
 

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Discussion Starter · #14 ·
OK...since I was intrigued by the boiling the crown race technique, so I did the simple calculation for how much diametral growth would result from heating the race to 220 deg F.
It ain't much. The I.D./O.D. of the race only grows by .0003". So...if you have a nominal .001" interference or so, you will still need a light press to push the race over the bulge at the base of the steerer tube.
 

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dirtrider7 said:
OK...since I was intrigued by the boiling the crown race technique, I did the simple calculation for how much diametral growth would result from heating the race to 220 deg F.
It ain't much. Only .0003". So...if you have a nominal .001" interference or so, you will still need a light press to push the race over the bulge at the base of the steerer tube.
Or you could have just boiled it and tried it to see if it worked.
And you wonder where all those how-many-engineers-does-it-take jokes come from.
Things are going to get real tricky when you attempt to calculate the proper amount of torque to use to preload your headset. You better get on it because suspension tends to go obsolete pretty quick.
 
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