Who does RS fork revalves these days?

Just fit some spacers behind the air piston to take up some volume but keep the same extension.

If you can measure the air springs side to side, or get the dimensions from another member here, it'd be easy to figure out exactly what volume you need to change the negative side by.

I assume the dampers are the same, the volumes in the lowers are the same, but the stanchions are longer and the placement of the sealhead is different.

Avalanche.

They will revalve your charger, if that's what you want. I'm actually currently running the avalanche pistons that I had in my pike, in my lyric. I wanted the full open bath damper below to simplify oil changes, to not have to worry about the bladder blowing again and again and for the adjustability/bottom out protection that you get.

I will say this, the avy charger just gobbles up the roots, very nice.

Here's my lyric cartridge. Just waiting for my oil to show up tomorrow.

You have a spring curve issue, not a damper issue.

Jm_ said:

Here's my lyric cartridge. Just waiting for my oil to show up tomorrow.

View attachment 122275

Click to expand...

F-yeah, SOO much more support from the damping. Like, oh, there's a massive-scary-root-complex, let me take it at full speed. Oh, there's a 5 foot drop and it didn't even use 98.2% of the travel like before. Many more lines opened up to me due to the damping support and lack of blowing-through-travel. This is going to rock at the park.

I was running the avy pistons before, but I can't be 100% sure I got the damping stacks fully transferred over to the lyric exactly as they were and I also felt my old pike with the avy mod didn't really have the low speed support, but that could have been due to what I specified or something else I suppose. This cartridge blows the charger out of the water.

When you go to push down on the fork, there's actually some resistance, feels like you have it pumped up way higher than you actually do, but that's the *real* low speed compression/support, which transfers nicely into that mid-stroke you are talking about. Rebound also seems very slow, typical of setting up a fork/shock with tuned high speed rebound/compression and letting the low speed rebound do it's thing. Can't wait till I get my Monarch+ back.

Apparently, as I swear on a Dungeons & Dragons Monster Manual that this thread wasn't showing up on my screen 30 minutes ago. Whatever I was on appears to have worn off now.

Anyway, dumb question dujour for Hacktastic, Udi, JM and maybe even Sandwich -

Hacktastic said:

You have a spring curve issue, not a damper issue.

Click to expand...

So I'm not sure I understand how the spring curve can affect the "mid-stroke support" issue in a meaningful way. I realize that one of the nice things about an air spring is that you have more ability to tune the spring curve compared to a traditional coil spring, but I can't imagine it can vary in a truly complex manner like say the leverage ratio of [gasp] a VPP bike. In other words, I can see how you could make it more progressive throughout the stroke, but I'm not sure how you could (for example) make it linear for the first 33% of the stroke, super progressive in the middle 33% of the stroke, and digressive at the end of the stroke. But maybe modern air springs are much more tunable than I realize and I've further cemented my status as the village idiot.

To me, mid-stroke support has more to do with damper design and shimz, in which case it would seem like the Avy option would be the way forward.

jackalope said:

(...) In other words, I can see how you could make it more progressive throughout the stroke, but I'm not sure how you could (for example) make it linear for the first 33% of the stroke, super progressive in the middle 33% of the stroke, and digressive at the end of the stroke. But maybe modern air springs are much more tunable than I realize and I've further cemented my status as the village idiot.

To me, mid-stroke support has more to do with damper design and shimz, in which case it would seem like the Avy option would be the way forward.

Click to expand...

Not in the extreme way you wrote about but a bit. The magic trick is the negative spring and/or a second chamber inside the positive spring. Size, location of the equalization point if present and pressure are to be considered.

For details ask @Udi or @Steve M

It is entirely possible to have reduced friction that correlates to less support, after all friction is just another form of damping. If reduced friction is indeed the cause of the change and the air spring curve is similar to the Pike (which it may or may not be, is it? I'd assume it's close) then that's probably not going to be the place you'll solve the problem. It's pretty easy to tell though - a simple push test with damping wound off (after a few cycles to ensure lubrication) and with equal spring rate should give a good indication if the Lyrik is different to the Pike on that front.

By all means get things as good as you can on the air spring curve via spacers etc, but to me it sounds like a good damper revalve (on the compression main piston) is probably your best bet. I'd be doing it myself, but the only other person I'd trust to nail this kind of thing is Steve M @ Vorsprung. Maybe drop him a line and see if you can ship him the damper cartridge alone or something like that.

I've rambled enough about springs in other threads, we probably don't need to hear more on that.

FWIW the new IRT thinger that manitou has for the mattoc and dorado claims to add mid stroke support. from what i can gather it essentially creates a dual rate air spring via two air chambers, each w/ its own schrader

Sandwich said:

I don't think you can tune a spring to do the crazy shit that you're talking about, but why would you want to? The overall force chart for your frame is the combination of the leverage rate, which changes through its travel, and the shock spring rate, which changes through its stroke (or doesn't). Generally bike designers either shoot for a leverage rate that takes advantage of a linear spring (progressive), or for weight uses an air spring with a different rate (deeply progressive-digressive). A fork is neither, it's completely linear and the ratio doesn't change. You can change the progressivity of the spring rate, if you want, but you can't really change the damping rate.

For "Mid-stroke support", I never quite know how people quantify that. I guess a fork that moves into its travel easily but doesn't dive and resists bottoming? I guess I always equate that to a reasonable amount of progression with consistent and firm low speed compression, with fairly fast rebound settings to keep the fork from packing up. Would love to know if I'm off base.

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Yeah, the example I gave was just intended to verify you couldn't do that, even if you were dumb enough to want to. Regarding the mythical "mid-stroke support" term, I've always thought of it as this magical scenario in which the fork would be pretty soft off the top (hooray negative springs!), then firm up in the "middle part" of the travel so it doesn't dive/wallow and finally get less progressive at the very end so you could actually use all the travel if you're hucking to gnar. But maybe that's almost ass-backwards and really what you want after the supple initial stroke is some variety of progression throughout the remaining stroke. I've just seen several examples of air sprung forks that were essentially impossible to get the full travel out of (my '13 Fox 36 Float RLC being an example). But once again, my 1% mental acuity presents profound problems when it comes to comprehending...well, much of anything.
Maybe I should go work for the Trump campaign?!

wydopen said:

Ive done that although with both running 6clicks of LSC and 9 rebound...lyrik definitely goes through the first part of the travel easier...

edit: will try again next time my friend brings his pike dpa over with compression backed off as I guess if damping is different 6clicks might be different from one fork to the other??

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IIRC the Lyric has a bigger negative Chamber. That alone might give it moar suppleness off the top.

Regarding the elusive mid stroke support, some brands such as X Fusion claim to address it through a "mid valve" (whatever that means) while others just trust a pyramidal shimstack to deliver the necessary support for the speed range the fork is suppossed to endure while tripping through that amount of travel.

Sandwich said:

For "Mid-stroke support", I never quite know how people quantify that. I guess a fork that moves into its travel easily but doesn't dive and resists bottoming? I guess I always equate that to a reasonable amount of progression with consistent and firm low speed compression, with fairly fast rebound settings to keep the fork from packing up. Would love to know if I'm off base.

Click to expand...

A progressive spring curve is actually the last thing you want for support. Given two very key factors about the front of a downhill bike...

1. A lack of support at the front of the bike causes OTB incidents at lower than peak riding velocities - i.e. less support means you have to ride slower or analyze the ground with your face. Also, any braking creates a moment that compresses the front suspension - unlike the rear
   
2. A lack of ability to counteract air spring curve anomalies, due to a 1:1 telescope rather than a variable rate linkage (like you said)

...support is much more critical on the front of a downhill bike than the rear. Which makes air springs a significantly bigger issue on the front than the rear - because not only can you not counteract curve issues, but riders commonly use a more progressive spring curve than is desirable to counteract the initial harshness that plagues air springs (a combination of early stroke rate, air preload effects, and increased friction which is present at all points in the stroke including the beginning).

The result of this is that you get closer to a fork that feels like a coil-sprung item, but if you compare the actual spring curve, what you get (if you match the average rate of the air spring to the flat value of the coil) is a lower rate in the middle of the stroke and a higher rate at the end. You can make further efforts to compensate this by running less pressure (which will give you better travel use at the cost of more dive / less support) or running more pressure (better support at the cost of reduced travel usage). You can also compensate with increased damping which certainly helps but net traction is reduced.

So setting up the best air-sprung fork is a careful balance of compromises. You want to use a little of all the tools available to minimise the ill-effects. You want some progression via spacers etc, so that you can run less spring pressure to alleviate breakaway forces and initial stroke harshness. You don't want too much spring progression since you don't want to limit travel use. Instead you can use a little spring progression and bring in stronger mid-speed compression damping to counteract blowing through the travel at the slightly lower (than ideal) pressures you're running to compensate for the initial stroke issues.

Why is it better to use a balance of tuning tools to fix the problem? Because while each tool contributes to solving the same problem, each tool also has a *different* downside, so you reduce the severity of damage in any single area (and should enjoy improved traction and comfort as a result).

@Mo(n)arch @jackalope I think this might interest you guys too.

slimshady said:

Regarding the elusive mid stroke support, some brands such as X Fusion claim to address it through a "mid valve" (whatever that means) while others just trust a pyramidal shimstack to deliver the necessary support for the speed range the fork is suppossed to endure while tripping through that amount of travel.

Click to expand...

Neither of those things target the middle of the stroke, modern damping is speed sensitive (only) and thus cannot target a position range, and a mid-valve just refers to the main/moving piston in a damper. Unfortunately many companies use the term mid-valve as a marketing line to make people think it correlates to mid-stroke support specifically, but in reality there is basically zero position sensitivity involved.

Flo33 said:

The magic trick is the negative spring and/or a second chamber inside the positive spring. Size, location of the equalization point if present and pressure are to be considered.

Click to expand...

There's actually a far more advanced solution I've been thinking about lately, it involves a helical device made of elastic material. I think someone may have already patented this technology for use in bedding or something though.

Since my previous post in this thread, I've conducted further research on re-purposing springs used in bedding and have noticed (in the linked article) that there are several key features which might make them useful in MTB applications. Unfortunately the technology is patented, but at least not by Specialized.



It seems they specifically target concerns of rate change during compression, providing initial softness for compliance with strong support after that.

Now that I think about it though, this article is very marketing-heavy, it seems unlikely that any spring technology could offer all these benefits without a clear downside. I suspect Mr. Louis Andrew might be tampering with the wikipedia page to boost sales. I suppose we should continue to focus on negative spring curves, low-friction air seals, volume tokens and damper mid-valves.

Udi said:

Neither of those things target the middle of the stroke, modern damping is speed sensitive (only) and thus cannot target a position range, and a mid-valve just refers to the main/moving piston in a damper. Unfortunately many companies use the term mid-valve as a marketing line to make people think it correlates to mid-stroke support specifically, but in reality there is basically zero position sensitivity involved.

Click to expand...

Gotcha. I wasn't actually talking about position sensitive damping, but about the speed sensitive one. The compression speed seems (at least to me) higher in the mid stroke, especially in air sprung forks, given the intrinsic progression of air (i. e. the spring should oppose a more powerful force at the end of the stroke).

Now please correct me where necessary, but if I understand you correctly the compression duties get splitted between the moving piston (which happens to control the rebound at the same time) for the medium speed stuff and a static piston, which handles the bottom out/high speed stuff. Does this sound coherent or do I need to go back to suspensión 101?

wydopen said:

How much air are you running in relation to whats printed on the leg and how much sag are you getting? Im pretty much off the charts as far as psi goes for my weight where with the pike I was running right about what they recommended...when I first put it on I put what was recommended for my weight and I was at like 30% sag when standing.....I dont even like to run 20% when standing

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I'm around 65psi or so, which is right about where I should be according to the leg. I'm about 170lbs or so. This puts me close to 20% sag. Avalanche says 22% is optimal and I should be running about 70psi, but that seemed like too little sag. I don't recommend running the Pike or Lyric with 30%, it's too much, they really seem best around 20% IME.

Air springs just aren't linear all-around. Add in a vacuum side with a positive pressure side, the issue compounds. Add in a position sensitive equalizing point (which most of these work off of), and the issue compounds even more.

Original poster wants to re-create the spring curve of his Pike air spring in his Lyrik air spring - we are assuming the dampers are the same, which I'm sure they are. Or close enough to it.

Air chamber diameters are the same, and so are the rod diameters (again, assuming). Travels are the same. So the only variables you have are: positive length (volume), negative length (volume), and equalizing position.

It has to be treated as two separate springs acting in parallel against the same surface. The positive spring character is predictable as a typical pneumatic chamber. So is the negative spring character, although a little more extreme in its gradient. But the resultant curve is additive. Since the change in volume on the negative side is >>100%, small changes in negative volume = big changes in curve.

http://forums.mtbr.com/shocks-suspension/air-spring-shock-modelling-682042.html

This touches on it a little bit, more with negative pressure rather than negative volume.

wydopen said:

yea I usually run between 15-18%
Im assuming you're getting your sag # by standing in attack position??
It's still tripping me out that the #s on the leg is so far off when the pike was spot on...almost makes me think there is something wrong with it....do you mind posting a pic of the air chart on your leg please? They are different between DPA and solo air...Ive got few setups of people similar in size to me and Id like to compare it although they are on solo airs...would like to compare what the difference is between the two so I can get an idea of what they are running...

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Err, I took that sticker off because my bike is "all black" . I think I was the other way around, Pike pressure was way lower for me than suggested. This is much close and the pressure I'm running is actually close to the sticker. Both were solo-airs. I want to say it was suggesting 65-70 or something like that. I don't like measuring sag in "attack" position all that much, as I like having more weight on the rear shock for when I get lazy or have bad technique and do a drop with my weight centered on the rear shock. I like measuring the sag seated with the dropper down, with body aggressively over the front, but I feel attack takes more weight off the rear shock.

This was posted by Andre in this thread:

http://ridemonkey.bikemag.com/threads/videos-mtb-rear-suspension-series.275496/page-2


This is exactly what has happened to your fork by switching between the two. All else being equal except the negative chamber length. If someone has numbers for those two units, that'll be very easy to quantify.


I just re-read the first post. Both forks are the dual position systems. Not sure how that complicates things over the normal Solo Air system, but if they both have positive and negative chambers, the above data still applies.

With the advances in coil spring material and lighter weight lowers, CSUs, etc. someone should produce a new coil sprung fork model. I mean you can still buy a coil Boxxer with a Charger damper, and with the endurofication of trail bikes and rear coils making a comeback, it seems to imply there is a market for it out there.

Nick said:

With the advances in coil spring material and lighter weight lowers, CSUs, etc. someone should produce a new coil sprung fork model. I mean you can still buy a coil Boxxer with a Charger damper, and with the endurofication of trail bikes and rear coils making a comeback, it seems to imply there is a market for it out there.

Click to expand...

I was just thinking exactly the same last night, after cleaning and regreasing a coil Fox 36 from a friend. That thing is in a whole another level when it comes to initial suppleness. A weight gain of 300g with the inclusion of a coil in a chassis like the new Formula 35 would put that hypothetical fork in the same ballpark of the Pike/Lyrik/Stage. That however means extra expenses for the brands, as they would have to include at least two extra coils with each fork. But I guess most people would be OK with that.

Nick said:

With the advances in coil spring material and lighter weight lowers, CSUs, etc. someone should produce a new coil sprung fork model. I mean you can still buy a coil Boxxer with a Charger damper, and with the endurofication of trail bikes and rear coils making a comeback, it seems to imply there is a market for it out there.

Click to expand...

Replace the air spring piston with a seat for a coil and room for a negative one on the other side. Maybe a top cap with a threaded preloader. Get a fox float from earlier than 2015 and some of that's already in there.

Sounds like a kit someone should offer. I wouldn't buy it because I don't think air forks are impossibru but I know some people who would.

What do those ti fox 40 springs weigh? Anybody know?

kidwoo said:

I don't think air forks are impossibru

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I guess I really don't either, but having the coil feel for a (tiny) weight penalty would definitely sell these days.


edit: My Pike feels amazing. I wish I could get the Monarch to feel anywhere close. Swapping the rear air to a coil would close to a pound. What's another half pound up front, right?

Nick said:

I guess I really don't either, but having the coil feel for a (tiny) weight penalty would definitely sell these days.

Click to expand...

I think the reason you're not seeing them is precisely because they weren't selling. I mean jesus you can't even buy a new fox 40 coil. That's just nuts. But I'm sure it's based at least a little in sales numbers comparisons that short while fox offered both. And people's willingness to buy 2008-2012 boxer world cups over and over again proves how much people want air. Those things were awful. They're way better now but I still think the WC boxxers vastly outsell the coil ones.

I don't have a decent scale but I went and grabbed the ti spring I took out of my 40 from 2013. A shorter version of that really wouldn't weigh very much. It would be a nice option for people spending hundreds of dollars on damping bandaids from push/avalanche etc, most of which really would be improved by just using a coil.

However, I'm not one of the people that just thinks coils are the end all be all of how to get well working suspension.
With so many years of fox coil 40s that just sucked, the tunability of air springs is something that does have value in cases like that. For years and years everyone had to run oversprung forks because there was no compression damping that worked worth a damn. You had to choose between oversprung or bottoming the shit out of the things constantly. Coils don't magically fix everything. It's just easier to damp because it's consistent. You have to actually do it though. And in the absence of that it's nice to be able to tune spring rates in a way that you can't do with a coil. Even my last gen coil 40 is kind of lacking IMO. Which is why I put that RS damper in there.

cliffnotes: still need gooder damping all round yo

Yeah, the bike parks should be only using air suspension, there's great stuff available and sending 150lb people out with 600lb springs is flat out negligent. I'm going to push this Lyrik a little more this weekend, but the damping is great and I think it will support it.

I've been running a titanium coil in the new 40 chassis for a couple years now, the weight difference from the air is approximately +150g (not 300) - the value is commonly over-assumed because the current air 40 saw a lot of weight savings in the chassis. Having ridden it back-to-back with both the coil-neg Float 40 (including a custom orange coil-neg sprung one from Cam Cole, which was my favourite air 40) and current air-neg Float 40 I think the full coil spring is squarely superior. I commented a few weeks ago that the legend Steve Smith was running a coil sprung Boxxer at the last two world cups as well.

RE dampers: I've ridden the RC2 damper (post 2011, every version since) all over the world, and having tried everything out there currently, it's still my favourite damper. I find it particularly good on very steep tracks. I run mine valved a little firmer than stock, but I'd be making far more drastic changes to a charger for example (notably in the HS comp valve design) to provide the same support.

slimshady said:

Gotcha. I wasn't actually talking about position sensitive damping, but about the speed sensitive one. The compression speed seems (at least to me) higher in the mid stroke, especially in air sprung forks, given the intrinsic progression of air (i. e. the spring should oppose a more powerful force at the end of the stroke).

Now please correct me where necessary, but if I understand you correctly the compression duties get splitted between the moving piston (which happens to control the rebound at the same time) for the medium speed stuff and a static piston, which handles the bottom out/high speed stuff. Does this sound coherent or do I need to go back to suspensión 101?

Click to expand...

Yes to split between a dynamic and static piston - but no they don't necessarily affect different speed ranges, and certainly not positions. I think you might be confusing spring curves with damper curves here - there is a *direct* correlation in rebound since the spring force dictates the shaft velocity and thus damping - however compression damping is *primarily* dependent on bump force and external load transfers.

It's up to the tuner to balance the valving between the two pistons - however an important consideration is cavitation - if you have much compression damping from the main piston you generate a strong vacuum on the rebound side of that piston. In a rear shock the piggyback pressure reduces this pressure differential, however most forks do not have pressurized dampers and thus benefit from just having a check valve on the main piston or very light compression damping, with most damping generated at the stationary piston as a result of shaft displacement.

Udi said:

I've been running a titanium coil in the new 40 chassis for a couple years now,

Click to expand...

How much did you have to gut out of the air spring to seat the coil? Or did you just grab an entire spring leg setup from an older fork?

I don't like the air 40s either. But the changes they've made in the RC2 are awesome.

See, I would have said that the primary reason folks went away from coils was the weight savings. But again, now that the other fork components can being manufactured much lighter ...

A 4-ish pound coil 36 or Pike? I can't believe those wouldn't sell "these days".

Oh make no mistake, it's definitely weight savings. That's an easy one to do. And if you can have a 4ish lb coil fork, the first question everyone's going to ask is 'where's my 3.9lb air fork?'

I'm not saying air is superior, just that some of its quirks can be improvements over poorly done coil forks.

kidwoo said:

How much did you have to gut out of the air spring to seat the coil? Or did you just grab an entire spring leg setup from an older fork?

Click to expand...

Used the spring rod and sealhead from same year 40R (you can use the rod from older forks too), and the titanium coil from previous year forks. The new stanchions are lighter so it's worth running those. I used the Float topcap and made up a spacer to be a bit lighter than the preload adjusting one but both work.

Running a 650b wheel but in the updated 26" lower to maintain the old offset. Plenty of clearance on the new style lowers, and 650 noticeably better in the rough stuff. Something tells me you'd appreciate the hell out of this fork.

Nick said:

See, I would have said that the primary reason folks went away from coils was the weight savings. But again, now that the other fork components can being manufactured much lighter ... A 4-ish pound coil 36 or Pike? I can't believe those wouldn't sell "these days".

Click to expand...

You nailed it here and with your post further up.
Forks are lighter now and we can go back to coil.
For anyone interested my "new" coil 40 weighs 2860g. I think a titanium coil in a new 36 could weigh 2000g.

Fox even published the exact weight saving breakdown for both the 36 and 40 Float forks so you could see how much the air spring saved compared to the lowers, crowns, stanchions, etc. I've posted them here before but can do so again if anyone wants - or just google.

Udi said:

Used the spring rod and sealhead from same year 40R (you can use the rod from older forks too), and the titanium coil from previous year forks. The new stanchions are lighter so it's worth running those. I used the Float topcap and made up a spacer to be a bit lighter than the preload adjusting one but both work.

Running a 650b wheel but in the updated 26" lower to maintain the old offset. Plenty of clearance on the new style lowers, and 650 noticeably better in the rough stuff. Something tells me you'd appreciate the hell out of this fork.

Click to expand...

Good info, thanks. I forgot about the 40R as a parts source.

Right now I'm debating between something like that or just getting a new RC2 damper to put in my old fork.




edit: but now that we've completely diverged, what's it gonna take to get a coil in wydopen's lyrik?

He wants the dual position feature, I suggest a U-turn assembly from an old psylo.

Coil guts from the old Lyrik slide right into the new Lyrik. A few friends here in N.Van are running new Lyrik's with coils.

The info on how to do it is over on the emptybeer buried under all the threads about what new plus tire will fit into some old XC frame from 2001 so a Joey can get more plush for his flat trails.

kidwoo said:

He wants the dual position feature, I suggest a U-turn assembly from an old psylo.

Click to expand...

Uhhh you know RS made a U-Turn Lyrik right? No need to dig back to the Psylo.

shirk007 said:

Uhhh you know RS made a U-Turn Lyrik right? No need to dig back to the Psylo.

Click to expand...

Uhhhh you realize psylo is a way funnier word right?

kidwoo said:

Uhhhh you realize psylo is a way funnier word right?

Click to expand...

Trying to fit 32mm internals in the new Lyrik would turn even funnier!

oh, and I want the Tullio QR back!

slimshady said:

Trying to fit 32mm internals in the new Lyrik would turn even funnier!

Click to expand...

Don't quote me on this but I think narrower things fit into larger diameter things.

We'll have to check with science.