Pike custom tuning

[teK--]

Has anyone had their Pike custom tuned? (the new style one with Charger damper).

Being on the light side, I find the HSC to be too high and would like to have this adjusted internally.

NS Dynamics say they can custom tune on top of a standard damper service for total of $100.00. Just wondering if anyone has had this or similar works done by NSD or other workshop.

The only other option I can see is an Avalanche open bath cartridge. They were amazing when I ran their cartridge in a Fox 34, but it's more coin than I would like to spend on the Pike which is already a very good fork in all other respects.

 

[SummitFever]

How comfortable are you with pulling the charger damper apart yourself? If you are, then post up the shim stack and I can give you some ideas on shim changes to give you less HSC. Also, make sure you are not wanting more HSC because you are running too much rebound damping causing the fork to feel feeling spiky because its running up against the really non-linear part of the air spring. It would be best to describe what it is the fork is doing that you don't like rather than jumping straight into "I want less HSC". One man's HSC may be another LSC.

 

[teK--]

Hi Summit

I haven't got the tools to dismantle and bleed the Charger. For the small investment of $100 I'd probably rather send it up to NSD rather than potentially spend half a day faffing around with it if I fudge it up. Thanks for offer to help with the shimstack though.

The reason why I want the HSC/HSR tuned, is due to the fork's behaviour over tree roots or medium sized square hits (rock gardens etc), mostly when there is a whole bunch lined up in quick succession. Either the fork is not compressing enough with each hit, or it is springing back too quickly. Or perhaps it's not springing back quickly enough and the forks are packing down.

This results in a jarring sensation and can bounce me off line. Maybe I need to set up a video camera from the side and shoot it in slow mo....

Don't think it's technique related as on the Tuned Fox 34 I had, it just floated over the same areas.

In any case do you think it's a HSC/HSR issue, or can it be tuned out using the LSC/LSR adjustments and spring rate/tokens?

Currently running just under 20% sag, 1 token, 2 clicks LSC, and LSR is halfway from full open.

 

[SummitFever]

Video camera is a great way to go, particularly if you've got one with a higher frame rate like 240fps.

If I had to guess, you've got too much rebound damping. Half closed for a light guy seems slow but each fork can be different. Counting clicks from fully closed is a better way to compare from fork to fork, but even then the actual number isn't that comparable.

I would try charging the same rock gardens with the rebound opened right up (fast as possible). A few clicks either way will be undetectable, but open it right up and see if that feels better or worse. Also, the Pike rebound adjuster works on a bleed port which allows fluid to bypass the rebound shims, so it affects both LSR and HSR (although more the LSR).

Also, the feel of your fork is highly dependent on how your rear suspension is set up. Too little rear sag, too little rear rebound damping or too much platform/LSC on the rear will make the fork do much more work and through successive hits kick the rear up thereby loading up the front. This will make even the best fork feel bad.

 

[SummitFever]

Also, $100 for a custom tune is good value, but it can be very difficult to convey to your tuner what exactly is wrong. Sometimes there are known issues with particular forks and shocks and this makes it easy, but for a fork like the Pike which is universally accepted as being pretty good (with no glaring f-ups from the factory) it will be just as easy to get a revalve wrong as getting it right.

 

[Rhys_]

The older 32 and 34 Fox forks were severely under damped when it came to HSC, which is what led to their very 'plush' feeling. This may have felt good at times, but it's not the ideal when it comes to aggressive riding and having a fork that stays up in its travel and 'with you'. What you are probably noticing is HSC actually doing something, compared to your old Fox. In the big scheme of things, a lot of people still consider the Pike to be under damped, so it's not like even it's running a lot of HSC. I'd harden up and reap the rewards in other riding situations :biggrin1:

 

[dug8713]

post up the shim stack and I can give you some ideas on shim changes to give you less HSC

The standard Pike shim stack configuration:

Compression
Ø18 X Ø6 X 0.1
Ø16 X Ø6 X 0.1
Ø18 X Ø16 X 0.15 (ring shim)
Ø18 X Ø6 X 0.1
Ø18 X Ø6 X 0.1
Ø18 X Ø6 X 0.1
Ø18 X Ø6 X 0.1
Ø8 X Ø6 X 0.4 (spacer shim)
Ø8 X Ø6 X 0.4 (spacer shim)
Ø8 X Ø6 X 0.4 (spacer shim)
Ø8 X Ø6 X 0.4 (spacer shim)
Ø8 X Ø6 X 0.4 (spacer shim)

Compression check plate
Ø16 X Ø7 X 0.1

Rebound
Ø16 X Ø6 X 0.1
Ø14 X Ø6 X 0.1
Ø16 X Ø14 X 0.1 (ring shim)
Ø16 X Ø6 X 0.1
Ø8 X Ø6 X 0.4 (spacer shim)
Ø8 X Ø6 X 0.4 (spacer shim)

Rebound check plate
Ø16 X Ø7 X Ø0.1

This is for 2014 RCT3, not sure about RC or if the shim stack have been revised on later years

 

[SummitFever]

The standard Pike shim stack configuration:

Compression
Ø18 X Ø6 X 0.1
Ø16 X Ø6 X 0.1
Ø18 X Ø16 X 0.15 (ring shim)
Ø18 X Ø6 X 0.1
Ø18 X Ø6 X 0.1
Ø18 X Ø6 X 0.1
Ø18 X Ø6 X 0.1
...

Great info dug8713. The the Pike has a straight stack of 18mm 0.1's with an 8mm clamp. For the DIY crowd wanting to reduce HSC this is fairly good news as a bit of shim removal is all that may be required (rather than having to go and buy some more shims). To drop the HSC but keep LSC about the same, remove shims further away from the piston. You could probably pull a couple out and test ride. Just make sure there is enough thread left to clamp the stack tight with the shims removed.

Just for info's sake. If you want to reduce the LSC, then move the position of the ring shim towards the piston face. Move it the other way for more LSC.

These straight stacks are very easy to tweak for the DIYer because of how primitive they are.

If you were a very light rider and needed to remove more shims, then its possible that the remaining shims would start fatiguing. At that point, we'd need to come up with a tapered stack to provide support for the reduced number of large diameter shims.

What's the RCT3 "midvalve" look like? It'll be masquerading as a rebound check plate with spring. Is that what you've described as the Rebound checkplate? When that midvalve opens, our comp piston will start to see much less oil flow. Any weirdness in that cross-over point will make the fork feel funny.

 

[dug8713]

What's the RCT3 "midvalve" look like? It'll be masquerading as a rebound check plate with spring. Is that what you've described as the Rebound checkplate? When that midvalve opens, our comp piston will start to see much less oil flow. Any weirdness in that cross-over point will make the fork feel funny.

That's even better info here!

As you've described, the check plate is the "mid valve". It has about 1mm of travel before the inner diameter hits the shoulder of the bolt & starts to flex.

Would you ever try fettling with the mid valve shim stack?

Sent from my GT-I9505 using Tapatalk

 

[SummitFever]

Absolutely. Indeed, high speed spiking can be caused by the mid-valve providing too much initial flow restriction. Once you include any sort of "mid-valve" it becomes one of the most important parts of the compression valving. The comp piston can only ever see the amount of oil displaced by the rebound rod volume. The mid valve is actually traveling through the oil so it can see a much larger "signal". If it doesn't work effectively then it can overload the comp valving by forcing too much oil through those circuits in high speed events.

In theory, a good mid valve will allow a comp piston tune with very little platform and great medium to HSC performance, with the mid-valve handling "float" and LSC events. Tune via both the mid-valve spring rate and the mid valve shim stack. This will mean removing LSC related damping from the comp piston and losing the ability to tune the LSC via adjusters. This is probably why bike fork manufacturers don't go down this path.

 

[teK--]

The older 32 and 34 Fox forks were severely under damped when it came to HSC, which is what led to their very 'plush' feeling. This may have felt good at times, but it's not the ideal when it comes to aggressive riding and having a fork that stays up in its travel and 'with you'. What you are probably noticing is HSC actually doing something, compared to your old Fox. In the big scheme of things, a lot of people still consider the Pike to be under damped, so it's not like even it's running a lot of HSC. I'd harden up and reap the rewards in other riding situations :biggrin1:

The Fox 34 I had, was fitted with an Avalanche custom tuned damper. However I agree with what you are saying in that the Pike being firmer and staying higher in its travel is good in many areas where the Fox 34 was too divey.

Video camera is a great way to go, particularly if you've got one with a higher frame rate like 240fps.

If I had to guess, you've got too much rebound damping. Half closed for a light guy seems slow but each fork can be different. Counting clicks from fully closed is a better way to compare from fork to fork, but even then the actual number isn't that comparable.

I would try charging the same rock gardens with the rebound opened right up (fast as possible). A few clicks either way will be undetectable, but open it right up and see if that feels better or worse. Also, the Pike rebound adjuster works on a bleed port which allows fluid to bypass the rebound shims, so it affects both LSR and HSR (although more the LSR).

Also, the feel of your fork is highly dependent on how your rear suspension is set up. Too little rear sag, too little rear rebound damping or too much platform/LSC on the rear will make the fork do much more work and through successive hits kick the rear up thereby loading up the front. This will make even the best fork feel bad.

Thanks I do think maybe there is too much LSR damping. I'm going to try full open like you suggest then bracket my way down to probably some sort of midpoint to what I have now. Also going to let out maybe 5psi to run closer to 20% sag since most rides I only use about 145 to 150 of the 160 travel except if I have a huge hit.

The rear is pretty much dialed, I spent a while tuning the LSR and running it slightly faster than the critical point where the rebound starts oscillating past full extension. Previously I ran it much faster and it used to buck off jumps and square hits but now it is perfect.

Also, $100 for a custom tune is good value, but it can be very difficult to convey to your tuner what exactly is wrong. Sometimes there are known issues with particular forks and shocks and this makes it easy, but for a fork like the Pike which is universally accepted as being pretty good (with no glaring f-ups from the factory) it will be just as easy to get a revalve wrong as getting it right.

I'll try these steps first cheers.

Lots of good info being shared including the shimstacks, the latter of which is a bit over my head though :nerd:

 

[teK--]

Just reporting outcome;

Dropped 2-3psi to hit 22% sag.

Reduced LSR by 4 clicks (now it is about 1/4 from full open).

LSC reduced by 2 clicks (now it is full open)

Much better now on rock gardens and small washboard bumps/roots. I suspect a lot of my problem was due to the forks packing down. The HSC could still do with some reduction but that's a job for another day!