Crown race extender spacer to increase AC length??

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tenbikes
Posts: 462
Joined: 11 Jan 2009, 6:41pm

Crown race extender spacer to increase AC length??

Post by tenbikes »

I'm wanting to increase AC length on my forks which have a very long steered so there is plenty of spare to fit a spacer.

Ie, a collar to fit before fitting the headset crown race ring.

Is there such a thing in the UK? Found one in the States....

TB
Wilhelmus
Posts: 124
Joined: 19 Oct 2021, 4:35pm

Re: Crown race extender spacer to increase AC length??

Post by Wilhelmus »

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Last edited by Wilhelmus on 25 Nov 2021, 1:46pm, edited 1 time in total.
PT1029
Posts: 1742
Joined: 16 Apr 2012, 9:20pm

Re: Crown race extender spacer to increase AC length??

Post by PT1029 »

The SJS spacers linked to are normal spacers, different to the ones the OP described.
Could the OP post a link the the American spacer he found (if only to satisfy my curiosity!). I can think of reasons why it might not be a very good idea, or have to be precision made for a certain fork.
If you are talking about a lot of spacing, you may well alter the head angle sufficiently to alter you bike's handling (for better or worse).
If the fork has a butted column (thicker wall thickness at the bottom), you might run the risk of the crown race stresses being taken by a thinner (none butted) section of the column
What ever extra spacing is provided, the spacer needs to be a very snug fit on the fork, with the crown race a snug fit on that.
tenbikes
Posts: 462
Joined: 11 Jan 2009, 6:41pm

Re: Crown race extender spacer to increase AC length??

Post by tenbikes »

I am wanting to change the head angle a little. I know from experience that this will improve handling.

I'm thinking that the spacer should be fairly thigh gauge, machined internally at the bottom to fit like a normal crown race bearing ring, and machined externally on the top to replicate the normal crown race of the fork.

It is a simple engineering/ turning job, if you have the tools!
NickJP
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Joined: 24 Sep 2018, 7:11pm
Location: Canberra, OZ

Re: Crown race extender spacer to increase AC length??

Post by NickJP »

I know that Chris King make taller fork crown races for their 1" and 1-1/8" headsets, as I have one on one of my bikes, but I don't know if any other manufacturer does the same. In any case, those races only give you an extra 5mm of height. The problem you're going to have with trying to put a spacer under a standard crown race is that the diameter of the steerer is greater at the crown race than higher up, so the race will be a loose fit unless at its intended location.

I'd say a new fork in the length you want is going to be cheaper than paying someone to machine what you want.
tatanab
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Joined: 8 Feb 2007, 12:37pm

Re: Crown race extender spacer to increase AC length??

Post by tatanab »

What is AC in this context? Not a cycling abbreviation I have seen before.
colin54
Posts: 2517
Joined: 24 Sep 2013, 4:34pm

Re: Crown race extender spacer to increase AC length??

Post by colin54 »

tatanab wrote: 26 Oct 2021, 7:08am What is AC in this context? Not a cycling abbreviation I have seen before.
[/quote
Axle to fork crown distance.
Nu-Fogey
tatanab
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Joined: 8 Feb 2007, 12:37pm

Re: Crown race extender spacer to increase AC length??

Post by tatanab »

colin54 wrote: 26 Oct 2021, 7:21am Axle to fork crown distance.
But the fork crown has not moved, only the bearing surface. I thought it might mean Above Crown. Can the OP point to the source of this abbreviation?
tenbikes
Posts: 462
Joined: 11 Jan 2009, 6:41pm

Re: Crown race extender spacer to increase AC length??

Post by tenbikes »

Yes it is axle to crown (race). Which if you use a spacer will increase.....
nsew
Posts: 1006
Joined: 14 Dec 2017, 12:38pm

Re: Crown race extender spacer to increase AC length??

Post by nsew »

MTB Tools in the US produce custom bike parts to order for very reasonable prices.

https://mtbtools.com/custom-parts/?v=79cba1185463

Example
https://mtbtools.com/product/extended-c ... cba1185463
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Chris Jeggo
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Joined: 3 Jul 2010, 9:44am
Location: Woking, Surrey

Re: Crown race extender spacer to increase AC length??

Post by Chris Jeggo »

colin54 wrote: 26 Oct 2021, 7:21am Axle to fork crown distance.
tatanab wrote: 26 Oct 2021, 7:45am But the fork crown has not moved, only the bearing surface. ...
Exactly. The distance the OP wants to increase is not the axle-crown distance.
(The axle-crown distance can determine what tyre cross-sections and front brakes can be used.)
Wilhelmus
Posts: 124
Joined: 19 Oct 2021, 4:35pm

Re: Crown race extender spacer to increase AC length??

Post by Wilhelmus »

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Last edited by Wilhelmus on 25 Nov 2021, 1:47pm, edited 1 time in total.
PH
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Location: Derby
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Re: Crown race extender spacer to increase AC length??

Post by PH »

I haven't come across such a spacer, though there are headsets which might also achieve what you're looking for, if you can get one in the size required. Example:
https://www.superstarcomponents.com/en/ ... eadset.htm
colin54
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Joined: 24 Sep 2013, 4:34pm

Re: Crown race extender spacer to increase AC length??

Post by colin54 »

Chris Jeggo wrote: 26 Oct 2021, 8:58am
colin54 wrote: 26 Oct 2021, 7:21am Axle to fork crown distance.
tatanab wrote: 26 Oct 2021, 7:45am But the fork crown has not moved, only the bearing surface. ...
Exactly. The distance the OP wants to increase is not the axle-crown distance.
(The axle-crown distance can determine what tyre cross-sections and front brakes can be used.)
My apologies for my lax use of terminology. I should perhaps have said 'axle to fork crown race bearing seat distance', which is what I meant, and what I've always understood (perhaps mistakenly) ,the abbreviation AC in the context of this thread to mean, tho' I would normally abbreviate it as A-C length/distance myself .
Nu-Fogey
tatanab
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Joined: 8 Feb 2007, 12:37pm

Re: Crown race extender spacer to increase AC length??

Post by tatanab »

colin54 wrote: 26 Oct 2021, 9:26amMy apologies for my lax use of terminology. I should perhaps have said 'axle to fork crown race bearing seat distance', which is what I meant, and what I've always understood (perhaps mistakenly) ,the abbreviation AC in the context of this thread to mean, tho' I would normally abbreviate it as A-C length/distance myself .
No fuss. I had never come across this abbreviation in 55 years of club riding across almost all disciplines. I thought this might be yet another home brewed abbreviation. As you say "in the context of the thread" is why I thought it might be "above crown"
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