2015 YT Capra Bos Kirk replacement for Fox X2

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2015 YT Capra Bos Kirk replacement for Fox X2
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Posted: Feb 28, 2017 at 6:06 Quote
Hi guys,

Just a quick post on changing the rear shock on my 2015 YT Capra CF Pro race. It's fitted with a Bos Kirk, which I'm swapping out for the Fox X2 with lock out (specially fitted to the 222x70 shock).

I emailed YT to get the correct frame bushing sizes and got the following response:

Unfortunately you can't use the X2 Shock on the CAPRA.
We needed to change the rockerarm of the CAPRA in order to fit the X2 on that frame.

Fox has a 2 mm tolearance in length of their shocks, which can lead to damages of the frame, when the shock is too long.
The rockerarm would damage the frame by hitting it.

The Specifications for the mounting hardware are:

22.2x 8 mm (frame)
34,0x 8 mm (rockerarm)

I hope this information is helpful to you.

Actually this doesn't help that much. Both the Bos Kirk and the Fox X2 are a 222mm x 70mm shock, so I can't see why the rocker arm would be difference in each application.

Any way, I'm going to try the shock deflated and check for clearance at the top and bottom of the stroke. I guest it will depend on the actual tolerances for my Fox X2 as to whether it works or not. I'll post some pictures and my results once fitted so others in the same boat have something to reference.

Posted: Mar 1, 2017 at 5:50 Quote
Hi there,

A little further info here. Got this reply back from YT:

Unfortunately we can't offer the rockerarm separately.

The shock is too long in total, so it would be 224 mm instead of 222 mm. The rocker arm would hit the seattube.
I don't know if this problem will show up, when you release the pressure of the shock.

The problem would show, when the shock is too long, so I guess in the top stroke or when the shock would be decompressing.
Because of the length of the shock this would push the rocker arm against the seattube, when the shock is decompressing.

Pretty disappointing that YT will not sell the revised rocker arm!

In any case, I'm going to try the shock and see how I get on with it. If I do have issues, I found these offset bushes that should cure the issue.


Posted: Mar 15, 2017 at 10:17 Quote
How did this work out ?

Posted: Mar 16, 2017 at 15:46 Quote
Hi there,

YT were correct, the FOX X2 is between 3-4mm longer than the factory BOS Kirk. When you fit the X2 the extra extension causes the rocker arm just and I mean only just make light contact with the frame.

One offset bush will offset the mounting by 2mm, which I don't think will be enough. As such, I've ordered 2x offset bushes 34mm and 22.2, which should do the job nicely.

Will update once they arrive and are fitted.

Posted: Mar 23, 2017 at 12:56 Quote
Shock successfully fitted tonight.

With two offset bushes fitted the Fox X2 is the same length as the BOS Kirk.

Ready to go for the weekend now!

Posted: Mar 24, 2017 at 13:33 Quote
Nice work. The colour matching on your bike is sick, 10/10 looks dude.

Posted: Mar 25, 2017 at 15:41 Quote
Glad to see that worked out for you!

Mind if we use those photos on our Instagram?

Jeron @ Offset Bushings

Posted: Apr 6, 2017 at 4:34 Quote
Hi Jeron,

Yes that's fine, go for it.

Posted: Apr 6, 2017 at 4:53 Quote
242spot wrote:
Shock successfully fitted tonight.

With two offset bushes fitted the Fox X2 is the same length as the BOS Kirk.

Ready to go for the weekend now!

woh yeah, 11/10 Book

Posted: Apr 6, 2017 at 12:11 Quote

do you think this could be the reason why you can't mount a 200x57mm Fox X2 on à Commencal Meta V4 ?

Or is it because the body of the shock is too wide and would not fit in the top tube?

Commencal just told me "it doesn't fit" but did not explain why.


Truly beautiful bike BTW, with great specs!

Posted: Aug 16, 2019 at 23:00 Quote
Hey, can you share opinion on the difference you got between the BOS and the Fox?

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