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Awesome thanks!
This is a follow up to a reply from @TEAMROBOT in a comment about the new RS shocks, because it relates to the pressure post above.
The top plot is a recent super deluxe (theres a few variations on the tunes, coil and air, high flow or not high flow piston but they have similar trends) set to fully closed, middle and fully open. In the firmer settings you can see how the force builds until the base valve opens and the line flattens off. In the bottom line there is no distinct knee which means we can assume it isn't building much pressure at the base valve. This design gives a lot of range, and probably quite noticeable but its more like a high speed adjuster. Because there is little pressure from the BV in the full open setting, you can't add much damping at the main piston either. It might be fine if you only ran in the firmer positions but there would be trouble if you set it fully open. It also has not much change below 127mm/s which is your body control/stability range. In my experience this range of adjustment gives an "OK" range, but you need to trade off support, bump absoprtion and bottoming control a lot more.
The lower plot is a different shock where the LSC dial has more change down to 25mm/s so the BV is doing much more work. From reading the press release it sounds like the new RS shocks will be somewhere closer to the bottom plot - maybe not the same, but if they can drop the IFP pressure to 120psi that signals to me a pretty big change
This was great. Thank you. I think I mostly understand-ish.
Oh yeah one other thing - I described the base valve as too "soft", when actually the shims are probably quite stiff, hence the large change in force available, its just they add too much extra free bleed or bypass when you open the LSC dial.
Also one small note about reading dyno graphs - the sharp bends in the curves look like valves open at a very distinct point, when actually thats just a PVP (peak velocity plot) graph which runs several speeds and only takes the peaks to make a single straight line. So the RS graph looks like the valve opens at exactly the same speed, when they would really open somewhere between that speed and the previous one measured
Slick move. I'm going to integrate that. Thanks man!
Yeah I often do the same if I need a more accurate measurement and not sure of the pressure change in the exact shock. Usually forks and shocks all change similar amounts but it you're testing something significantly different then its a good way to do it
This might be of interest to the readers of this thread, methinks: https://www.vitalmtb.com/product/guide/forks/ohlins/rxf38-m-3-68486#product-reviews-764016.
I hope everyone will forgive a very basic parts and maintenance question, but it does relate to suspension modifications.
I run SKF dual compound seals and an aftermarket damper (in this case, a Lift) in a Lyrik. I'm trying to figure how to replace the bushings and seals on the air spring. The 200 hour service kit is $75. I don't want the dust wipers and don't need the damper parts. While it'd feel wasteful and gross, I could just buy a new air spring for a tad over $90 and throw the old one away.
Am I missing something? What are people doing?
You can just buy the o-rings (and 1 quad ring) from a seal supplier and replace the ones on the current air piston and sealhead. Measure it for yourself, but its normally a #213 quad ring on the piston and a 10x3 o-ring against the shaft. The wiper there is normally fine
Or just buy and air spring and sell your old one to someone wanting to change travel. And if your fork isn't already buttercup equipped then you get a buttercup upgrade at the same time (assuming its a recent lyrik....otherwise disregard that part)
Huge thanks for that. Really appreciate all the knowledge you share on here. I'll pick up some o-rings and change them more regularly to boot. I remember your post about them degrading from time alone.
And just any old o-rings of the proper size will do? There's nothing special about them? You sure they're not aerospace grade?
My fork does have buttercups. Do you have any thoughts on how important it is to change out that little elastomer and with what frequency?
Yeah just Nitrile N70 o-rings (sometimes called NBR or Buna-N) - some places only do quad rings in N80 but thats fine too. Either way they are all extremely common standard Jellybean parts. You will occasionally seen Viton and Polyurethane o-rings but they are still easy to source if you really need it (just more expensive) but the majority of push bike products don't need anything that special and operate within the range of Nitrile. Shock wiper seals are often polyurethane for extra durability though
Couple tips on o-ring sizes, which is helpful if measuring and knowing what to order-
*Like most things imperial sizing is very common, so when I say a #213 o-ring (or Q-ring) the 2 means it is 3.53mm cross section. And the second 2 numbers relate to ID so a 214 is the next size up from 213. #1 is 2.62mm and #0 is 1.78mm
*There are a few metric sizes, like 1, 1.5, 2 and 3mm. So normally when you measure a seal it won't line up exactly with one of those or the imperial sizes, but factoring in that they stretch or compress slightly, you just go with the next closest one. ie if you measure one at 1.7mm or 2.9mm, don't go looking for that size - they were originally 1.78 and 3mm.
*The ID of an air piston seal will grow slightly, so if it looks like you are in between 2 sizes, go with the slightly smaller one. 99.999999% of the time they only come in standard increments, and most major brands use standard sizes. It only seems to be smaller brands that use weird sizes, as though they didn't fully factor that in during the design process (normally they would design the seal housing etc around the appropriate size seal for the application, but a few brands seems to miss that part.....like they make the seal housing and then find the closest seal that fits, even if its a weird size)
*A shaft seal might compress slightly, but generally the easiest way to know you've got the right size, is the ID of the seal will match the shaft size (eg a 10mm air shaft uses a 10mm ID o-ring) Installing it in the sealhead is what compresses it slightly to squeeze the air shaft.
Buttercups - in theory they do break down but I have noticed variation in them even from new so probably doesn't matter that much. I also believe their main benefit isn't really to do with absorbing bumps directly, but they correct misalignment in the same way as Fox's new glidecore springs. I still don't if Rockshox intended that or would ever admit it, but thats the hypothesis I'm sticking too until I get proven wrong!
I bought this DVO used for $75 and it gave me two strong seasons out of it. Worth servicing, or just buy a new shock? Compression is blown.
Probably not...those ones used a 10mm shaft which wasn't super durable, so you will likely need at least a new damper body and shaft on top of the service. There's a few updates/revisions you would need to look out for when its apart, so if you send it to DVO it should go OK but not everyone is that familiar with them...And you might find it doesn't last very long
The dampers have potential but the newer Gen 3 shock with a 1/2" steel shaft is a lot more robust so would be worth servicing, but the older ones you need to be careful with
Good to know.
It was a great shock, felt fine and just worked. I know the weight of the ebike can make any shock feel good, but this one genuinely did. Never felt it packing up, and never bottomed hard (until the compression blew and it bottoms hard on everything now)
Will a charger 3 (or 3.1,3.2...) RC2 fit inside a SID35 chasis? I have a frame lying around that will do with a 120, or even 110mm travel, "light" fork, but xc dampers are not my cup of tea, and a Pike is not particularly light, at least on paper
Check the reservoir pressure with a shock pump before you consign it to "blown", they were notorious for leaky valves and no pressure in the system feels the same as blown.
Good call out. Any idea what it should be?
I was going to link you to the service manual but forgot over the years that in hilariously DVO fashion...bruh, we totally spaced on including the 'pressurize the bladder' step in the published service manual. 🤪
From memory it's 150-180psi
Hey all, Tried to post the in the other thred..And I guess as a dealer I would have to give it a week or so for all FOX employees to catch up. But I have the all gold fox 40, Witch I believe is the 2025. Damper adjustment say X2. Does that mean I can drop in the new glidecore airshaft, And if I want new dampner??
Damper, no N.
You will need a response from fox. this is a new chassis so there is no guarentee that the air spring is a drop in. I would be very surprised if the damper (no n) isn't a drop in to the previous generation.
Ok, Only reason I asked is that the OTHER colored side said ALL adjustments are backwards doable. It was confusing..lol.
My Jade is 170-200.
I also seem to remember something around 200 psi in the bladder. I also had a Topaz, I warrantied a Super Deluxe in 2020 and it was taking so long that I bought a replacement Topaz for the time being and by the time I got the Super Deluxe back, I could warranty the Topaz because it didn't hold air in the bladder. I could actually see some oil leaking out around some seals on the piggyback if I remember correctly though. So might be something else leaking too.
Yeah I think bladder pressure is 170-200 psi or there abouts, depending on the feel you're looking for. I bought a used one to try at one point and that damn thing leaked and felt like it was blown. Guy I sold it to said he could fix it and wasn't worried - I was just happy to be rid of it.
Adding here for the folks not in the other discussion, yes, for 40 the Glidecore air spring and new Grip X2 damper are compatible with MY25 and MY26 forks. Apologies for missing this question here.
Can any math/suspension nerds answer this for me please
Does higher IFP pressure in the piggyback reservoir decrease sensitivity (increasing brake away friction) or is it largely fixed by damper design (i.e how much pressure is generated on the oil side of the IFP) and the friction/area of the seal.
Obviously there is a trade off, you could have a very small piston with a higher pressure (charge) or a large piston diameter and lower charge. Does it really change much?
Higher pressure puts more load on the seals, which in turn adds friction. It also pushes on the area of the shaft so with a large shaft and/or high pressure you effectively add extra preload. The difference between a low pressure, small shaft system and something with a higher spring force would be over 10kg at the shock so if you can safely reduce that its worthwhile. As for the IFP itself, a larger diameter needs to travel less for an equivalent shaft displacement compared to a smaller IFP so it can respond much quicker as well.
Jade x D3 I have in my hand says 120-180psi
Yep, that’s a different shock with different internal architecture and has different pressure requirements. New shock uses the new bladder pressure range. Older shocks will cavitate at 120psi and are to be set to 170-200psi.
https://tech.dvosuspension.com/tuning/jade/bladder/
Also look at the shock in the picture that’s being discussed, bladder pressure sticker can be seen, it’s the 170-200 range.
Yeah they made a couple of updates to the bladder (made it thicker) and the resi cap (latest ones are black) which made a massive improvement to reliability.
Also the base valving was crazy stiff so the internal pressures would cause the rebound aduster o-ring to extrude out of the body after a while. If you make that shim stack much lighter you can prevent that happening too
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