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cyco biker
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Local MX shop or web search

I know nothing of the NZ market but found shims here in the US thru a web search of suspension shims. Your best resource may be a local motocross shop; they should be able to help. Michigan Engineering http://www.mei-inc.com/machine/ will ship internationally, if you don't find a resource locally. When you get to their site, go to the main menu & click "suspension shims" then click "production shims" then click "ID 8 mm " & wa la, you have more choices than you can imagine. I believe they sell in bags of 10 but they are pretty inexpensive.
 

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Shimmie

We can always stick something in the mail too!
Adding another 15mm @ .15 thickness will reduce small and mid bump compliance.
It will add good compression for big single hits, but i suspect you'll not like the added hand slap.
Experiment with thinner shims, such as: 21mmX.10. Use 2 of these stacked.
The .10mm thick shims give much more tuning options and greatly reduce the "slap" and if stacked right still retians good big hit compression.
You can usually get all 8mm i.d. in .10mm thickness.
Generally you'll find that reducing the shimmed compression will allow you to run more air pressure for better bottom out and brake dive, with out the added harshness from a combonation of too much pressure and too much compression damping from the shims.
Using the thinner shims also allows the use of thicker oil for better rebound control, again, without the harshness from thick oil and standerd shim stacks.
Alpamayo can attest the smoothness from changing to these shims...

Thin shim stack start point: (starting at piston)
21mm X .10 -qty 1
18mm X .10 -qty 1
12mm X .15 -qty 1
21mm X .15 (this is used as a backer shim, to keep thinner shims from bending too far)
Experiment from there, two .10mm shims will flex easier than one .15mm, so that tells you what you can do with thnner shims stacked for your ride style.
 

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Discussion Starter · #4 ·
Thanks Ethan

The intention is to improve the big hit compression. I have the fork tuned for a more linear feel (5ml 10wt oil in the air spring) but it does blow through the travel pretty easily on big hits. I don't want to increase the air spring pressure (currently 140psi but this equates to 15% sag). When I reduce the spring pressure to 125psi it feels way too soft.

Small bump compliance is currently good.

So the plan is have a linear feeling fork with 25% sag that has good small bump compliance but doesn't bottom out on 1-2 foot drop offs. I did have more oil in the air spring to give a more progressive feel but would prefer a linear rate.

Do you have the suggested shims at your end?

Cheers
 

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I'd try the 15mm shim for that application, if all else feels pretty good.
Also add pressure to the damper, this helps bottom out, but stays linear for 2/3rds travel.
You can add 18cc total to the air chamber, and go to 100-110psi in the damper if needed.
 
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