Ok, so how do you call elements in such architecture like RS Super Deluxe (prior 2023):
Ok, so how do you call elements in such architecture like RS Super Deluxe (prior 2023):
From the image you shared you've highlighted two things:
The valve located in the head unit is the "Base Valve". The shock shaft displaces fluid when it enters the shock body which is forced through this valve generating compression damping. The valve also features a replenishment circuit that allows the displaced fluid to freely move back into the shock body on the rebound stroke. The replenish is generally designed to not produce any rebound restriction or damping. Base Valves are generally designed to manage more of the low and mid-velocity compression damping characteristics with a fine resolution.
The second item you pointed out is the main damping piston. The damping piston is what moves through the fluid housed in the shock body and has a circuit for compression damping on one side, and rebound damping on the other side. The main damping piston is designed to manage the entire velocity range with a course resolution.
Dirty booger: "You can then ask the important questions like why is RockShox so enamored with digressive compression and rebound stacks?"
Pedaling platform in my opinion. Walking a tightrope between gooshy, saggy while pedaling and getting the "popoff*" just to be at the velocity of a human leg at 65 cadence.
* too weird of an example to use the dyno sheet reader term "knee"
I don't know, I think frame kinematics have helped pedaling platform vastly with the extreme anti squat values, etc seen these days. And almost all shocks have some form of lockout/climb lever as well. Seems like a big performance negative just for pedaling platform. All that digression makes the shock feel so dead.
Maybe it has more to do with mfg tolerances. RS parts tend to be a bit sloppy, and from everything I have pulled apart, they have the biggest occurrence of shim lift (where the edge of the face shim will lift off the piston when torqued down). Perhaps they love preloaded shim stacks because they help prevent shim lift.
I pulled a SD Ultimate from a Santa Cruz HT apart to tune and every single shim stack was preloaded. The comp and rebound on the main piston, the base valve (always preloaded on SD shocks), and even the "needle stack"/rebound check was preloaded!
Speaking of rebound check valve shim stacks, I would love to hear your opinion @PUSH Industries on this as a tuning option.
For shocks that use a shim stack on the rebound check, like current Fox Float X/DHX and RS Super Deluxe (pre'23), what is the effect of a stiffer or softer stack on performance? Does it affect the low speed rebound range and therefore when the main rebound stack will open? What else does it have an influence on?
All Fox shocks have the exact same rebound check shim stack regardless of shock tune, while RockShox has 3-4 different ones they use.
I don't know, I think frame kinematics have helped pedaling platform vastly with the extreme anti squat values, etc seen these days. And almost all shocks...
I don't know, I think frame kinematics have helped pedaling platform vastly with the extreme anti squat values, etc seen these days. And almost all shocks have some form of lockout/climb lever as well. Seems like a big performance negative just for pedaling platform. All that digression makes the shock feel so dead.
Maybe it has more to do with mfg tolerances. RS parts tend to be a bit sloppy, and from everything I have pulled apart, they have the biggest occurrence of shim lift (where the edge of the face shim will lift off the piston when torqued down). Perhaps they love preloaded shim stacks because they help prevent shim lift.
I pulled a SD Ultimate from a Santa Cruz HT apart to tune and every single shim stack was preloaded. The comp and rebound on the main piston, the base valve (always preloaded on SD shocks), and even the "needle stack"/rebound check was preloaded!
I think you're on the right track. Variations in shim thickness (tenths of thousandths) can have a HUGE impact on the force required to move them. With a flat face piston, this can result in the damping variation that you allude to.
Dishing the shim stack has an even greater effect (in the grand scheme of things) , so even a tiny bit of dish takes away much of the influence of shim thickness problems.
Speaking of rebound check valve shim stacks, I would love to hear your opinion @PUSH Industries on this as a tuning option.
For shocks that use...
Speaking of rebound check valve shim stacks, I would love to hear your opinion @PUSH Industries on this as a tuning option.
For shocks that use a shim stack on the rebound check, like current Fox Float X/DHX and RS Super Deluxe (pre'23), what is the effect of a stiffer or softer stack on performance? Does it affect the low speed rebound range and therefore when the main rebound stack will open? What else does it have an influence on?
All Fox shocks have the exact same rebound check shim stack regardless of shock tune, while RockShox has 3-4 different ones they use.
I don't really have an opinion either way. We go the route of FOX where we use fixed bleeds that, when checked, are simply a check and don't result in damping force. I would say that it's not common to use the free bleed as another tuning component, but there's nothing that keeps you from doing it.
I'd like to understand how charger 3 works on the new rockshox fork and how they designed low and high speed compression to be independent of each other. If I close low speed based on their diagram, oil is only flowing through the high speed circuit but it looks like oil flow path for high speed is less restrictive than if high speed and low speed was open, so wouldn't it feel spiky and harsh on fast impact? Same for the opposite if I increase high speed compression or even close it all the way, it looks like low speed compression is dictated by what the high speed pyramid needle thing will allow.
I believe you are correct. What they are calling HSC is simply a typical LSC type needle that is stepped and controls all flow through the base valve, so there is no way it cannot effect the LSC circuit since it is upstream from it.
There is no bypass like in the Charger 2.1 where oil can go through the piston bolt and skip the shim stack entirely and only be controlled by the LSC needle.
Maybe they are claiming that even with the HSC closed, the flow through it is still in the low speed realm and therefore it does not effect the LSC circuit. But I have messed with one out of the fork, and when you crank the HSC all the way, low speed is definitely effected based on my "hand dyno".
The HSC is not the typical version either as it does not simply increase force required to open a shim stack or poppet valve, but it chokes flow to the whole system.
Not a fan of the Charger 3, seems like a few steps backwards.
I believe you are correct. What they are calling HSC is simply a typical LSC type needle that is stepped and controls all flow through the...
I believe you are correct. What they are calling HSC is simply a typical LSC type needle that is stepped and controls all flow through the base valve, so there is no way it cannot effect the LSC circuit since it is upstream from it.
There is no bypass like in the Charger 2.1 where oil can go through the piston bolt and skip the shim stack entirely and only be controlled by the LSC needle.
Maybe they are claiming that even with the HSC closed, the flow through it is still in the low speed realm and therefore it does not effect the LSC circuit. But I have messed with one out of the fork, and when you crank the HSC all the way, low speed is definitely effected based on my "hand dyno".
The HSC is not the typical version either as it does not simply increase force required to open a shim stack or poppet valve, but it chokes flow to the whole system.
Not a fan of the Charger 3, seems like a few steps backwards.
Thanks for the input, validates how I feel with the fork. Charger feels good in most scenario but those quick square edge hits are harsh. Lesson learned not to always hop on the latest tech. I'll probably send it out for a tune to see if I can address that issue.
Thanks for the input, validates how I feel with the fork. Charger feels good in most scenario but those quick square edge hits are harsh. Lesson...
Thanks for the input, validates how I feel with the fork. Charger feels good in most scenario but those quick square edge hits are harsh. Lesson learned not to always hop on the latest tech. I'll probably send it out for a tune to see if I can address that issue.
It's ok, Charger3.7.5.1 will solve all the issues.
I'd like to understand how charger 3 works on the new rockshox fork and how they designed low and high speed compression to be independent of...
I'd like to understand how charger 3 works on the new rockshox fork and how they designed low and high speed compression to be independent of each other. If I close low speed based on their diagram, oil is only flowing through the high speed circuit but it looks like oil flow path for high speed is less restrictive than if high speed and low speed was open, so wouldn't it feel spiky and harsh on fast impact? Same for the opposite if I increase high speed compression or even close it all the way, it looks like low speed compression is dictated by what the high speed pyramid needle thing will allow.
It's a kind of a partial block that changes the flow rate of oil on to the base valve, since reducing the cross section creates higher-velocity flow through that region. The analogy of putting your thumb over the end of a garden hose is most commonly used here - you limit the size of the hole so the water escapes the hose at higher speed (even once its left the hose and in to an "infinitely" wide region).
It never fully closes, and the cross section of the valve is still pretty large so not directly adding much damping on its own, its job is to increase the affect of the shimmed valve by speeding up the oil before it reaches there. Thats why at low speeds it doesn't do anything. Racetech use a similar concept in there more modern Gold Valves (motorcycles) where a stepped piston face lets you add washers of different diameters to reduce the port area. It's also semi-related to the base valve/main piston discussion - part of a base valves job is to increase pressure in front of the main piston, which changes the flow of the oil through the main compression shims. Both are examples of how valves can create different damping forces when paired with another valve, and its more than simply adding the 2 together.
As for the 'cross talk' reference they make in the literature - this normally refers to the interaction between a rebound adjuster and compression damping which doesn't really affect forks anyway. This new damper is improved in a lot of ways in that the low speed adjuster has more control at actual low speeds/less at high speed. That was one of the drawbacks of 2/2.1 which was kind of baked in to the architecture of the damper and couldn't be tuned out. The rebound circuit is also improved IMO, (previous version was very light) and theres a bunch of super interesting things they have done with the damper which I think are pretty clever. Maybe not earth-shattering developments but nice attention to detail touches anyway!
I believe that mid valves are common in rear shock? Especially RockShocks with piggiback all use mid valve, they have 2 compression stack, one on the...
I believe that mid valves are common in rear shock? Especially RockShocks with piggiback all use mid valve, they have 2 compression stack, one on the piston and a base valve near piggyback. I think that Bomber CR does that as well. Or maybe this is just a naming thing?
Rear shocks do not have Mid-Valves.
Let's take a 170mm travel trail bike:
Front wheel travel is 170mm, fork travel is 170mm.
Front Fork Wheel Velocity...
Rear shocks do not have Mid-Valves.
Let's take a 170mm travel trail bike:
Front wheel travel is 170mm, fork travel is 170mm.
Front Fork Wheel Velocity Range is 0-9m/sec, fork velocity is 0-9m/sec
Rear wheel travel is 170mm, shock travel is 65mm.
Rear wheel velocity is 0-7m/sec, shock velocity is 0-2.7m/sec
This is due to the fact that rear shocks are driven by a linkage or pivot system so the motion is not directly 1:1 like a front fork.
Because forks are dealing with a larger travel and velocity range, mid-valves were introduced as another tuning element to reduce compromise over these larger ranges. They provide support in the middle of the travel, or in the mid-velocity range.
Mid valves are found on the backside of the rebound piston and have two elements. The first is free bleed, or float as it's sometimes referred to, which prevents the mid valve from producing compression damping at low-velocity ranges where it's easy for cavitation to form. The second element is the compression stack, or compression spring, etc which actually creates a small amount of compression damping in a specific velocity range before opening fully.
-Darren
"Rear shocks do not have Mid-Valves."
"Mid valves are found on the backside of the rebound piston and have two elements. The first is free bleed... The second element is the compression stack..."
Then what do you call the free-bleed and the compression stack on the piston on a RockShox Deluxe? If these aren't mid-valves (since all rear shocks do not have mid-valves?), then where are the (fixed) base-valves on an inline rear shock?
I understand there may be terminology differences, but you seem to be saying that things that we can see with our own eyes somehow don't exist.
Oh, lkubica recently basically asked the same thing, with helpful pictures!
Everyone here should read this if you have not yet, pretty sure it's available in e-form. It will answer many of the questions posed here, and...
Everyone here should read this if you have not yet, pretty sure it's available in e-form. It will answer many of the questions posed here, and cut through the confusion.
You can then ask the important questions like why is RockShox so enamored with digressive compression and rebound stacks?
In regards to mid valves on fork dampers, many of them can have a rather large compression effect that can produce spiking at higher velocities and add to a harsh feeling. To test this on yours; close the (low speed) rebound adjuster all the way, which closes the bleed around the mid valve forcing more fluid through it instead. Now push on the fork, for some dampers it will feel as if you added tons of compression damping. Although you would never ride this way (rebound fully closed), it illustrates the effect the mid valve can have on compression damping when the bleed is overwhelmed. This is also why it is especially helpful for heavier riders who have the LSR adjuster near closed to have the damper re-valved. The more the LSR bleed is closed, the more the mid valve will produce a spike in compression. If you can add rebound damping via the shim stack instead of closing the LSR needle, you are able to keep the LSR bleed more open and allow more fluid to bypass the mid valve on compression.
"You can then ask the important questions like why is RockShox so enamored with digressive compression and rebound stacks?"
I think it's because that makes changes to the low-speed adjustments (free-bleed mostly) more noticeable when pushing on the bars or doing a parking lot test. They don't care that actual riding with big hits and deep compressions feel terrible since the high-speed damping "falls off" relative to how the low-speed feels. It's "selling more bikes equipped with RS parts" vs making actual good dampers, IMHO, based on my 100 kgs going from 2016 Fox 36 RC2 to 2019 Pike RC to 2020 Fox 36 R2C2. I can make the 36s feel like the Pike by basically opening the high-speed circuits and cranking up the low-speed: "rattly", easy to blow through, less controlled. I end up running the 36s the opposite way: fairly closed on HS, pretty open on LS.
From the image you shared you've highlighted two things:
The valve located in the head unit is the "Base Valve". The shock shaft displaces fluid when...
From the image you shared you've highlighted two things:
The valve located in the head unit is the "Base Valve". The shock shaft displaces fluid when it enters the shock body which is forced through this valve generating compression damping. The valve also features a replenishment circuit that allows the displaced fluid to freely move back into the shock body on the rebound stroke. The replenish is generally designed to not produce any rebound restriction or damping. Base Valves are generally designed to manage more of the low and mid-velocity compression damping characteristics with a fine resolution.
The second item you pointed out is the main damping piston. The damping piston is what moves through the fluid housed in the shock body and has a circuit for compression damping on one side, and rebound damping on the other side. The main damping piston is designed to manage the entire velocity range with a course resolution.
-Darren
Previously:
"Mid Valve: This is when you are creating compression damping on the backside of the rebound damper piston. This is often just a check valve"
Is it just a check valve, or is it a "circuit for compression damping"? You've said both, and since Fox (and SRAM IIRC) has a handful of pre-specced stacks for the compression side of the damper piston for most shocks, it certainly seems to be more than a simple check valve.
RE: the replenishment circuit
"Twin-tube"* shocks can and do replenish/recirculate fluid back into the shock body during the compression stroke. This seems to be the whole damn point of them.
*(in the bike context of shocks like X2 and TTX, not the context of vehicle shocks using twin-tubes to get rid of the IFP and moving the gas chamber to the outer tube)
"Rear shocks do not have Mid-Valves."
"Mid valves are found on the backside of the rebound piston and have two elements. The first is free bleed...
"Rear shocks do not have Mid-Valves."
"Mid valves are found on the backside of the rebound piston and have two elements. The first is free bleed... The second element is the compression stack..."
Then what do you call the free-bleed and the compression stack on the piston on a RockShox Deluxe? If these aren't mid-valves (since all rear shocks do not have mid-valves?), then where are the (fixed) base-valves on an inline rear shock?
I understand there may be terminology differences, but you seem to be saying that things that we can see with our own eyes somehow don't exist.
Oh, lkubica recently basically asked the same thing, with helpful pictures!
You took my quote out of context. The complete quote was:
"Mid valves are found on the backside of the rebound piston and have two elements. The first is free bleed, or float as it's sometimes referred to, which prevents the mid valve from producing compression damping at low-velocity ranges where it's easy for cavitation to form. The second element is the compression stack, or compression spring, etc which actually creates a small amount of compression damping in a specific velocity range before opening fully."
The key is that the mid-valve has float (secondary free bleed) independent from the rebound free bleed. This is due to the fact that mid-valves are found in non, or very low-pressurized systems (Bladder or IFP forks where these are for compensation, and not for pressurization). Mid-valves are generally designed to create damping in the mid-velocity range and are not designed to create damping over the entire velocity range.
On a rear shock, you have the compression stack which does not float and is designed to create damping over the entire compression velocity range (Low, Mid, and High-Speed). This is the arrangement that is used in mid to high-pressurization systems (bladder of IFP with a gas charge behind it creating continuous lifting force even at full extension).
Inline shock: Piston
Inline shock with external reservoir and compression: Piston and Base Valve
Twin Tube Inline Shock: Piston and Base Valve
Twin Tube Shock with external reservoir and compression: Piston and Base Valve
Bladder Fork Cartridge: Base Valve(optional), Rebound Piston, Mid Valve(optional)
IFP Fork Cartridge: Base Valve(optional), Rebound Piston, Mid Valve(optional)
Previously:
"Mid Valve: This is when you are creating compression damping on the backside of the rebound damper piston. This is often just a check valve"...
Previously:
"Mid Valve: This is when you are creating compression damping on the backside of the rebound damper piston. This is often just a check valve"
Is it just a check valve, or is it a "circuit for compression damping"? You've said both, and since Fox (and SRAM IIRC) has a handful of pre-specced stacks for the compression side of the damper piston for most shocks, it certainly seems to be more than a simple check valve.
RE: the replenishment circuit
"Twin-tube"* shocks can and do replenish/recirculate fluid back into the shock body during the compression stroke. This seems to be the whole damn point of them.
*(in the bike context of shocks like X2 and TTX, not the context of vehicle shocks using twin-tubes to get rid of the IFP and moving the gas chamber to the outer tube)
Non or low-pressure system (Bladder or IFP fork cartridge) is creating compression damping: Mid-Valve
Non or low-pressure system (Bladder or IFP fork cartridge) is not creating compression damping: Check Valve
We have examples of both in MTB suspension.
You had previously asked the question: "But does the oil flow in both directions at once in the Monarch and others?" I was simply saying that oil does not flow in two directions at once. If flows and displaces in one direction on the compression stroke, and then flows and displaces in the opposite direction on the rebound stroke. Regardless of mono or twin tube design.
Anyone who knows me know what's coming... how can we make CSUs reliable enough to handle our riding and current geo? Or should we go to dual crowns for anything over 150mm? Personally, I'd like to see DC forks take over, I'm so sick of CSUs dying.
Maybe I've just had astronomically bad luck, but in 8 years I've gone through I think (edit, tallied them up) 7 CSUs from 3 brands. Sure, the first 4 of those were Fox, but I moved on to other brands and got more life, but the same problem . I now sell every single crown before it's out of warranty (puts on tinfoil hat after typing this). I'm just-a-guy, not at the pointy end, and ranged from 190-205 lbs kitted up, so within the bell curve on weight. This has to be getting expensive for brands, and it sucks for consumers.
What EXT is doing looks clever, but that still leaves the stanchion-CSU interface.
Anyone who knows me know what's coming... how can we make CSUs reliable enough to handle our riding and current geo? Or should we go to...
Anyone who knows me know what's coming... how can we make CSUs reliable enough to handle our riding and current geo? Or should we go to dual crowns for anything over 150mm? Personally, I'd like to see DC forks take over, I'm so sick of CSUs dying.
Maybe I've just had astronomically bad luck, but in 8 years I've gone through I think (edit, tallied them up) 7 CSUs from 3 brands. Sure, the first 4 of those were Fox, but I moved on to other brands and got more life, but the same problem . I now sell every single crown before it's out of warranty (puts on tinfoil hat after typing this). I'm just-a-guy, not at the pointy end, and ranged from 190-205 lbs kitted up, so within the bell curve on weight. This has to be getting expensive for brands, and it sucks for consumers.
What EXT is doing looks clever, but that still leaves the stanchion-CSU interface.
What's the solution to this all too common issue?
I have an Ohlins 34 with a 1 piece crown and steerer, not sure if they are still doing it on their more recent offerings?
Anyone who knows me know what's coming... how can we make CSUs reliable enough to handle our riding and current geo? Or should we go to...
Anyone who knows me know what's coming... how can we make CSUs reliable enough to handle our riding and current geo? Or should we go to dual crowns for anything over 150mm? Personally, I'd like to see DC forks take over, I'm so sick of CSUs dying.
Maybe I've just had astronomically bad luck, but in 8 years I've gone through I think (edit, tallied them up) 7 CSUs from 3 brands. Sure, the first 4 of those were Fox, but I moved on to other brands and got more life, but the same problem . I now sell every single crown before it's out of warranty (puts on tinfoil hat after typing this). I'm just-a-guy, not at the pointy end, and ranged from 190-205 lbs kitted up, so within the bell curve on weight. This has to be getting expensive for brands, and it sucks for consumers.
What EXT is doing looks clever, but that still leaves the stanchion-CSU interface.
What's the solution to this all too common issue?
The way ext does it is perhaps the best and still cost effective way compared to single piece csu. If you look at typical fork, overlap of steerer/crown is the same or less than overlap of crown/stanchions. And there are two stanchion tubes to spread the load(on 99% of forks). Can the fork creak in stanchion/crown joint? Sure, but it's lot less likely when they are bonded together properly in the first place. Short answer would be, yes, DC forks are the way to go if you are not in desperate need of barspins/tailwhips on your regular trail/ Enduro ride.
I want to take a moment to thank Darren from Push, who has a small business to run, for taking time to weigh in and educate mouth breathers like me about what's happening inside our suspension stuff that goes up-and-down. I've learned a ton from reading so far. Thanks, Darren!
One thing to point out about recent CSU problems, and I think I've posted about this before on tech rumors, is that they're really a function of bigger wheels for two reasons. First is that longer wheels and forks create more leverage at the CSU, and that's not a small factor. A 29" wheel and fork is a 40mm longer lever than an equivalent travel 26" wheel and fork. Second, that extra 40mm of stack height was a sticking point against the adoption of early 29ers, so (counterintuitively) manufacturers moved to shorter CSU assemblies with less steerer tube/crown overlap to reduce stack when they introduced 27.5 and 29" forks.
So at the same time that longer forks generated more leverage, they were also given shorter crowns to handle all that force. I remember way back in 2013 or so when Fox introduced the 27.5" and 29" 36 fork, they were bragging about how they shaved 10mm of stack height off the crown vs. the 26" version and saved a bunch of weight in the process 😬. I think we've been digging ourselves out of that hole ever since. Change is possible, though. I know the new 29" Zeb is 10 or 15mm taller than a 29" Lyrik of the same travel, and most of that is just due to crown height. Thank God. Smaller riders who don't want the extra front end height of a Zeb can fork-down to a 170mm Lyrik, and they'll probably benefit from a slightly flexier fork anyway. My two cents.
Interestingly, the stanchion/crown interface isn't constrained by stack height in the same way as the steerer tube/crown interface. They can make the crown taller or shorter around the stanchions and it just affects what shape and dimensions the lowers need to be cast in.
One thing to point out about recent CSU problems, and I think I've posted about this before on tech rumors, is that they're really a function...
One thing to point out about recent CSU problems, and I think I've posted about this before on tech rumors, is that they're really a function of bigger wheels for two reasons. First is that longer wheels and forks create more leverage at the CSU, and that's not a small factor. A 29" wheel and fork is a 40mm longer lever than an equivalent travel 26" wheel and fork. Second, that extra 40mm of stack height was a sticking point against the adoption of early 29ers, so (counterintuitively) manufacturers moved to shorter CSU assemblies with less steerer tube/crown overlap to reduce stack when they introduced 27.5 and 29" forks.
So at the same time that longer forks generated more leverage, they were also given shorter crowns to handle all that force. I remember way back in 2013 or so when Fox introduced the 27.5" and 29" 36 fork, they were bragging about how they shaved 10mm of stack height off the crown vs. the 26" version and saved a bunch of weight in the process 😬. I think we've been digging ourselves out of that hole ever since. Change is possible, though. I know the new 29" Zeb is 10 or 15mm taller than a 29" Lyrik of the same travel, and most of that is just due to crown height. Thank God. Smaller riders who don't want the extra front end height of a Zeb can fork-down to a 170mm Lyrik, and they'll probably benefit from a slightly flexier fork anyway. My two cents.
Interestingly, the stanchion/crown interface isn't constrained by stack height in the same way as the steerer tube/crown interface. They can make the crown taller or shorter around the stanchions and it just affects what shape and dimensions the lowers need to be cast in.
Yeah that sums it up - CSU's are always going to have the potential to creak when they are made by pressing thin alloy tubes in to alloy forgings. Going with less overlap at the same time as longer travel / larger wheels exacerbated the issue big time. Older 32mm forks probably creaked just as much but we couldn't hear it over the sound of chains and derailleurs banging on chainstays!
It could probably be reduced easily with a combination of a few mm stack height, a few grams of weight and a little bit more cost (for extra manufacturing processes) but people will absolutely not accept any of those things.
Supposedly the new Fox 38 with a taller crown is much more reliable, but that was coming from Fox themselves so not sure how much I would trust that.....
Rockshox filed a patent for stanchion surface treatments which would include texturing in the stanchion/crown interface and allow for the use of adhesives. That sounds like a potential cure, but is an extra step (and cost) in the manufacturing process. currently we just press smooth alloy tubes which don't give much space for a reliable adhesive to be use. Bearing in mind the ideal surface finish for a pressfit is VERY different to the ideal surface finish tube of a sliding on a teflon bushing!
I want to take a moment to thank Darren from Push, who has a small business to run, for taking time to weigh in and educate...
I want to take a moment to thank Darren from Push, who has a small business to run, for taking time to weigh in and educate mouth breathers like me about what's happening inside our suspension stuff that goes up-and-down. I've learned a ton from reading so far. Thanks, Darren!
For sure, there were so many industry guys giving really good info on MTBR suspension forum until a certain Kiwi with a hard on for Manitous (wonder who that could be) picked fights with all of them for no reason and it's a ghost town of it's former self. Darren was one of those guys who gave a lot of fantastic info. So cheers to him.
I want to take a moment to thank Darren from Push, who has a small business to run, for taking time to weigh in and educate...
I want to take a moment to thank Darren from Push, who has a small business to run, for taking time to weigh in and educate mouth breathers like me about what's happening inside our suspension stuff that goes up-and-down. I've learned a ton from reading so far. Thanks, Darren!
Hmmmm....Teamrobot is giving kudos? Has to be a prank!
One thing to point out about recent CSU problems, and I think I've posted about this before on tech rumors, is that they're really a function...
One thing to point out about recent CSU problems, and I think I've posted about this before on tech rumors, is that they're really a function of bigger wheels for two reasons. First is that longer wheels and forks create more leverage at the CSU, and that's not a small factor. A 29" wheel and fork is a 40mm longer lever than an equivalent travel 26" wheel and fork. Second, that extra 40mm of stack height was a sticking point against the adoption of early 29ers, so (counterintuitively) manufacturers moved to shorter CSU assemblies with less steerer tube/crown overlap to reduce stack when they introduced 27.5 and 29" forks.
So at the same time that longer forks generated more leverage, they were also given shorter crowns to handle all that force. I remember way back in 2013 or so when Fox introduced the 27.5" and 29" 36 fork, they were bragging about how they shaved 10mm of stack height off the crown vs. the 26" version and saved a bunch of weight in the process 😬. I think we've been digging ourselves out of that hole ever since. Change is possible, though. I know the new 29" Zeb is 10 or 15mm taller than a 29" Lyrik of the same travel, and most of that is just due to crown height. Thank God. Smaller riders who don't want the extra front end height of a Zeb can fork-down to a 170mm Lyrik, and they'll probably benefit from a slightly flexier fork anyway. My two cents.
Interestingly, the stanchion/crown interface isn't constrained by stack height in the same way as the steerer tube/crown interface. They can make the crown taller or shorter around the stanchions and it just affects what shape and dimensions the lowers need to be cast in.
Yeah that sums it up - CSU's are always going to have the potential to creak when they are made by pressing thin alloy tubes in...
Yeah that sums it up - CSU's are always going to have the potential to creak when they are made by pressing thin alloy tubes in to alloy forgings. Going with less overlap at the same time as longer travel / larger wheels exacerbated the issue big time. Older 32mm forks probably creaked just as much but we couldn't hear it over the sound of chains and derailleurs banging on chainstays!
It could probably be reduced easily with a combination of a few mm stack height, a few grams of weight and a little bit more cost (for extra manufacturing processes) but people will absolutely not accept any of those things.
Supposedly the new Fox 38 with a taller crown is much more reliable, but that was coming from Fox themselves so not sure how much I would trust that.....
Rockshox filed a patent for stanchion surface treatments which would include texturing in the stanchion/crown interface and allow for the use of adhesives. That sounds like a potential cure, but is an extra step (and cost) in the manufacturing process. currently we just press smooth alloy tubes which don't give much space for a reliable adhesive to be use. Bearing in mind the ideal surface finish for a pressfit is VERY different to the ideal surface finish tube of a sliding on a teflon bushing!
The additional on cost to make the steerer/crown/stanchion more robust has surely got to outweigh the deluge of warranty claims for creaky CSU's. Both my Zebs are due a major service (the 23 needs it bushings resizing, but RS won't hold their hands up to that one and fix it!), whilst they are in, will have them pushed apart and glued back together.
One thing to point out about recent CSU problems, and I think I've posted about this before on tech rumors, is that they're really a function...
One thing to point out about recent CSU problems, and I think I've posted about this before on tech rumors, is that they're really a function of bigger wheels for two reasons. First is that longer wheels and forks create more leverage at the CSU, and that's not a small factor. A 29" wheel and fork is a 40mm longer lever than an equivalent travel 26" wheel and fork. Second, that extra 40mm of stack height was a sticking point against the adoption of early 29ers, so (counterintuitively) manufacturers moved to shorter CSU assemblies with less steerer tube/crown overlap to reduce stack when they introduced 27.5 and 29" forks.
So at the same time that longer forks generated more leverage, they were also given shorter crowns to handle all that force. I remember way back in 2013 or so when Fox introduced the 27.5" and 29" 36 fork, they were bragging about how they shaved 10mm of stack height off the crown vs. the 26" version and saved a bunch of weight in the process 😬. I think we've been digging ourselves out of that hole ever since. Change is possible, though. I know the new 29" Zeb is 10 or 15mm taller than a 29" Lyrik of the same travel, and most of that is just due to crown height. Thank God. Smaller riders who don't want the extra front end height of a Zeb can fork-down to a 170mm Lyrik, and they'll probably benefit from a slightly flexier fork anyway. My two cents.
Interestingly, the stanchion/crown interface isn't constrained by stack height in the same way as the steerer tube/crown interface. They can make the crown taller or shorter around the stanchions and it just affects what shape and dimensions the lowers need to be cast in.
Yeah that sums it up - CSU's are always going to have the potential to creak when they are made by pressing thin alloy tubes in...
Yeah that sums it up - CSU's are always going to have the potential to creak when they are made by pressing thin alloy tubes in to alloy forgings. Going with less overlap at the same time as longer travel / larger wheels exacerbated the issue big time. Older 32mm forks probably creaked just as much but we couldn't hear it over the sound of chains and derailleurs banging on chainstays!
It could probably be reduced easily with a combination of a few mm stack height, a few grams of weight and a little bit more cost (for extra manufacturing processes) but people will absolutely not accept any of those things.
Supposedly the new Fox 38 with a taller crown is much more reliable, but that was coming from Fox themselves so not sure how much I would trust that.....
Rockshox filed a patent for stanchion surface treatments which would include texturing in the stanchion/crown interface and allow for the use of adhesives. That sounds like a potential cure, but is an extra step (and cost) in the manufacturing process. currently we just press smooth alloy tubes which don't give much space for a reliable adhesive to be use. Bearing in mind the ideal surface finish for a pressfit is VERY different to the ideal surface finish tube of a sliding on a teflon bushing!
Back in the day (when they had in-house suspension), Specialized played with bonding alloy tubes in alloy crowns.
It actually worked really well, passed all testing no problem. They were even ride tested after 100k+ cycles of abuse in the test lab and remained creak free and strong. Upper management decided to drop all in house suspension efforts, otherwise they would have gone into production.
One of the other things it allowed, which is still a major issues with current offering from RS and Fox that are pressed in, is that it allowed for perfect alignment of the stanchion tubes every time due to the bonding fixtures used.
It is currently quite common to see stanchion tubes that are 0.02"+ splayed out or in (or twisted) from the crown interface to the end of the tubes. It may seem small, but it is more than enough to make a fork bind in the bushings and feel like poo.
With good surface prep, correct bond gap/alignment design, and correct adhesive; bonding tubes into crowns is the way to go.
I never came across a creaky Blackbox carbon crown on the Revelation - though perhaps the small sample size influenced my perception, I only saw a handful of them. They appeared to be bonded.
One thing to point out about recent CSU problems, and I think I've posted about this before on tech rumors, is that they're really a function...
One thing to point out about recent CSU problems, and I think I've posted about this before on tech rumors, is that they're really a function of bigger wheels for two reasons. First is that longer wheels and forks create more leverage at the CSU, and that's not a small factor. A 29" wheel and fork is a 40mm longer lever than an equivalent travel 26" wheel and fork. Second, that extra 40mm of stack height was a sticking point against the adoption of early 29ers, so (counterintuitively) manufacturers moved to shorter CSU assemblies with less steerer tube/crown overlap to reduce stack when they introduced 27.5 and 29" forks.
So at the same time that longer forks generated more leverage, they were also given shorter crowns to handle all that force. I remember way back in 2013 or so when Fox introduced the 27.5" and 29" 36 fork, they were bragging about how they shaved 10mm of stack height off the crown vs. the 26" version and saved a bunch of weight in the process 😬. I think we've been digging ourselves out of that hole ever since. Change is possible, though. I know the new 29" Zeb is 10 or 15mm taller than a 29" Lyrik of the same travel, and most of that is just due to crown height. Thank God. Smaller riders who don't want the extra front end height of a Zeb can fork-down to a 170mm Lyrik, and they'll probably benefit from a slightly flexier fork anyway. My two cents.
Interestingly, the stanchion/crown interface isn't constrained by stack height in the same way as the steerer tube/crown interface. They can make the crown taller or shorter around the stanchions and it just affects what shape and dimensions the lowers need to be cast in.
Yeah that sums it up - CSU's are always going to have the potential to creak when they are made by pressing thin alloy tubes in...
Yeah that sums it up - CSU's are always going to have the potential to creak when they are made by pressing thin alloy tubes in to alloy forgings. Going with less overlap at the same time as longer travel / larger wheels exacerbated the issue big time. Older 32mm forks probably creaked just as much but we couldn't hear it over the sound of chains and derailleurs banging on chainstays!
It could probably be reduced easily with a combination of a few mm stack height, a few grams of weight and a little bit more cost (for extra manufacturing processes) but people will absolutely not accept any of those things.
Supposedly the new Fox 38 with a taller crown is much more reliable, but that was coming from Fox themselves so not sure how much I would trust that.....
Rockshox filed a patent for stanchion surface treatments which would include texturing in the stanchion/crown interface and allow for the use of adhesives. That sounds like a potential cure, but is an extra step (and cost) in the manufacturing process. currently we just press smooth alloy tubes which don't give much space for a reliable adhesive to be use. Bearing in mind the ideal surface finish for a pressfit is VERY different to the ideal surface finish tube of a sliding on a teflon bushing!
Back in the day (when they had in-house suspension), Specialized played with bonding alloy tubes in alloy crowns.
It actually worked really well, passed all testing...
Back in the day (when they had in-house suspension), Specialized played with bonding alloy tubes in alloy crowns.
It actually worked really well, passed all testing no problem. They were even ride tested after 100k+ cycles of abuse in the test lab and remained creak free and strong. Upper management decided to drop all in house suspension efforts, otherwise they would have gone into production.
One of the other things it allowed, which is still a major issues with current offering from RS and Fox that are pressed in, is that it allowed for perfect alignment of the stanchion tubes every time due to the bonding fixtures used.
It is currently quite common to see stanchion tubes that are 0.02"+ splayed out or in (or twisted) from the crown interface to the end of the tubes. It may seem small, but it is more than enough to make a fork bind in the bushings and feel like poo.
With good surface prep, correct bond gap/alignment design, and correct adhesive; bonding tubes into crowns is the way to go.
Yeah I've seen an increase in mis-aligned CSU's in the last few years. One of several things that seemed like rushed production in the covid era. They're never been perfect but were at least close enough to not be noticeable. Never as bad as some of the old (08 era) marzocchis where I would get with 1 mm difference between the top and the bottom of the stanchions. People would always be looking at all kinds of tuning or mods to do on those forks and I was like my dude these are beyond help.......
I never came across a creaky Blackbox carbon crown on the Revelation - though perhaps the small sample size influenced my perception, I only saw a...
I never came across a creaky Blackbox carbon crown on the Revelation - though perhaps the small sample size influenced my perception, I only saw a handful of them. They appeared to be bonded.
Yeah the creaking is from the fretting that happens between 2 aluminium surfaces when they rub together so alloy-carbon wouldn't do it as much. Those forks however would leak air in to the steerer tube!
*edit - forgot to mention that the stanchion/crown overlap is limited by downtube clearance - as we went to wider hub spacing, larger stanchions and 29" wheels (steeper down tubes) the clearance can be super tight between the dials and the frames. In theory though as the steerer overlap increases you can add an equal amount of height to the stanchion interface
From the image you shared you've highlighted two things:
The valve located in the head unit is the "Base Valve". The shock shaft displaces fluid when it enters the shock body which is forced through this valve generating compression damping. The valve also features a replenishment circuit that allows the displaced fluid to freely move back into the shock body on the rebound stroke. The replenish is generally designed to not produce any rebound restriction or damping. Base Valves are generally designed to manage more of the low and mid-velocity compression damping characteristics with a fine resolution.
The second item you pointed out is the main damping piston. The damping piston is what moves through the fluid housed in the shock body and has a circuit for compression damping on one side, and rebound damping on the other side. The main damping piston is designed to manage the entire velocity range with a course resolution.
-Darren
Dirty booger: "You can then ask the important questions like why is RockShox so enamored with digressive compression and rebound stacks?"
Pedaling platform in my opinion. Walking a tightrope between gooshy, saggy while pedaling and getting the "popoff*" just to be at the velocity of a human leg at 65 cadence.
* too weird of an example to use the dyno sheet reader term "knee"
I don't know, I think frame kinematics have helped pedaling platform vastly with the extreme anti squat values, etc seen these days. And almost all shocks have some form of lockout/climb lever as well. Seems like a big performance negative just for pedaling platform. All that digression makes the shock feel so dead.
Maybe it has more to do with mfg tolerances. RS parts tend to be a bit sloppy, and from everything I have pulled apart, they have the biggest occurrence of shim lift (where the edge of the face shim will lift off the piston when torqued down). Perhaps they love preloaded shim stacks because they help prevent shim lift.
I pulled a SD Ultimate from a Santa Cruz HT apart to tune and every single shim stack was preloaded. The comp and rebound on the main piston, the base valve (always preloaded on SD shocks), and even the "needle stack"/rebound check was preloaded!
Speaking of rebound check valve shim stacks, I would love to hear your opinion @PUSH Industries on this as a tuning option.
For shocks that use a shim stack on the rebound check, like current Fox Float X/DHX and RS Super Deluxe (pre'23), what is the effect of a stiffer or softer stack on performance? Does it affect the low speed rebound range and therefore when the main rebound stack will open? What else does it have an influence on?
All Fox shocks have the exact same rebound check shim stack regardless of shock tune, while RockShox has 3-4 different ones they use.
I think you're on the right track. Variations in shim thickness (tenths of thousandths) can have a HUGE impact on the force required to move them. With a flat face piston, this can result in the damping variation that you allude to.
Dishing the shim stack has an even greater effect (in the grand scheme of things) , so even a tiny bit of dish takes away much of the influence of shim thickness problems.
I don't really have an opinion either way. We go the route of FOX where we use fixed bleeds that, when checked, are simply a check and don't result in damping force. I would say that it's not common to use the free bleed as another tuning component, but there's nothing that keeps you from doing it.
-Darren
I'd like to understand how charger 3 works on the new rockshox fork and how they designed low and high speed compression to be independent of each other. If I close low speed based on their diagram, oil is only flowing through the high speed circuit but it looks like oil flow path for high speed is less restrictive than if high speed and low speed was open, so wouldn't it feel spiky and harsh on fast impact? Same for the opposite if I increase high speed compression or even close it all the way, it looks like low speed compression is dictated by what the high speed pyramid needle thing will allow.
I believe you are correct. What they are calling HSC is simply a typical LSC type needle that is stepped and controls all flow through the base valve, so there is no way it cannot effect the LSC circuit since it is upstream from it.
There is no bypass like in the Charger 2.1 where oil can go through the piston bolt and skip the shim stack entirely and only be controlled by the LSC needle.
Maybe they are claiming that even with the HSC closed, the flow through it is still in the low speed realm and therefore it does not effect the LSC circuit. But I have messed with one out of the fork, and when you crank the HSC all the way, low speed is definitely effected based on my "hand dyno".
The HSC is not the typical version either as it does not simply increase force required to open a shim stack or poppet valve, but it chokes flow to the whole system.
Not a fan of the Charger 3, seems like a few steps backwards.
Thanks for the input, validates how I feel with the fork. Charger feels good in most scenario but those quick square edge hits are harsh. Lesson learned not to always hop on the latest tech. I'll probably send it out for a tune to see if I can address that issue.
It's ok, Charger3.7.5.1 will solve all the issues.
It's a kind of a partial block that changes the flow rate of oil on to the base valve, since reducing the cross section creates higher-velocity flow through that region. The analogy of putting your thumb over the end of a garden hose is most commonly used here - you limit the size of the hole so the water escapes the hose at higher speed (even once its left the hose and in to an "infinitely" wide region).
It never fully closes, and the cross section of the valve is still pretty large so not directly adding much damping on its own, its job is to increase the affect of the shimmed valve by speeding up the oil before it reaches there. Thats why at low speeds it doesn't do anything. Racetech use a similar concept in there more modern Gold Valves (motorcycles) where a stepped piston face lets you add washers of different diameters to reduce the port area. It's also semi-related to the base valve/main piston discussion - part of a base valves job is to increase pressure in front of the main piston, which changes the flow of the oil through the main compression shims. Both are examples of how valves can create different damping forces when paired with another valve, and its more than simply adding the 2 together.
As for the 'cross talk' reference they make in the literature - this normally refers to the interaction between a rebound adjuster and compression damping which doesn't really affect forks anyway. This new damper is improved in a lot of ways in that the low speed adjuster has more control at actual low speeds/less at high speed. That was one of the drawbacks of 2/2.1 which was kind of baked in to the architecture of the damper and couldn't be tuned out. The rebound circuit is also improved IMO, (previous version was very light) and theres a bunch of super interesting things they have done with the damper which I think are pretty clever. Maybe not earth-shattering developments but nice attention to detail touches anyway!
"Rear shocks do not have Mid-Valves."
"Mid valves are found on the backside of the rebound piston and have two elements. The first is free bleed... The second element is the compression stack..."
Then what do you call the free-bleed and the compression stack on the piston on a RockShox Deluxe? If these aren't mid-valves (since all rear shocks do not have mid-valves?), then where are the (fixed) base-valves on an inline rear shock?
I understand there may be terminology differences, but you seem to be saying that things that we can see with our own eyes somehow don't exist.
Oh, lkubica recently basically asked the same thing, with helpful pictures!
"You can then ask the important questions like why is RockShox so enamored with digressive compression and rebound stacks?"
I think it's because that makes changes to the low-speed adjustments (free-bleed mostly) more noticeable when pushing on the bars or doing a parking lot test. They don't care that actual riding with big hits and deep compressions feel terrible since the high-speed damping "falls off" relative to how the low-speed feels. It's "selling more bikes equipped with RS parts" vs making actual good dampers, IMHO, based on my 100 kgs going from 2016 Fox 36 RC2 to 2019 Pike RC to 2020 Fox 36 R2C2. I can make the 36s feel like the Pike by basically opening the high-speed circuits and cranking up the low-speed: "rattly", easy to blow through, less controlled. I end up running the 36s the opposite way: fairly closed on HS, pretty open on LS.
Previously:
"Mid Valve: This is when you are creating compression damping on the backside of the rebound damper piston. This is often just a check valve"
Is it just a check valve, or is it a "circuit for compression damping"? You've said both, and since Fox (and SRAM IIRC) has a handful of pre-specced stacks for the compression side of the damper piston for most shocks, it certainly seems to be more than a simple check valve.
RE: the replenishment circuit
"Twin-tube"* shocks can and do replenish/recirculate fluid back into the shock body during the compression stroke. This seems to be the whole damn point of them.
*(in the bike context of shocks like X2 and TTX, not the context of vehicle shocks using twin-tubes to get rid of the IFP and moving the gas chamber to the outer tube)
You took my quote out of context. The complete quote was:
"Mid valves are found on the backside of the rebound piston and have two elements. The first is free bleed, or float as it's sometimes referred to, which prevents the mid valve from producing compression damping at low-velocity ranges where it's easy for cavitation to form. The second element is the compression stack, or compression spring, etc which actually creates a small amount of compression damping in a specific velocity range before opening fully."
The key is that the mid-valve has float (secondary free bleed) independent from the rebound free bleed. This is due to the fact that mid-valves are found in non, or very low-pressurized systems (Bladder or IFP forks where these are for compensation, and not for pressurization). Mid-valves are generally designed to create damping in the mid-velocity range and are not designed to create damping over the entire velocity range.
On a rear shock, you have the compression stack which does not float and is designed to create damping over the entire compression velocity range (Low, Mid, and High-Speed). This is the arrangement that is used in mid to high-pressurization systems (bladder of IFP with a gas charge behind it creating continuous lifting force even at full extension).
Inline shock: Piston
Inline shock with external reservoir and compression: Piston and Base Valve
Twin Tube Inline Shock: Piston and Base Valve
Twin Tube Shock with external reservoir and compression: Piston and Base Valve
Bladder Fork Cartridge: Base Valve(optional), Rebound Piston, Mid Valve(optional)
IFP Fork Cartridge: Base Valve(optional), Rebound Piston, Mid Valve(optional)
-Darren
Non or low-pressure system (Bladder or IFP fork cartridge) is creating compression damping: Mid-Valve
Non or low-pressure system (Bladder or IFP fork cartridge) is not creating compression damping: Check Valve
We have examples of both in MTB suspension.
You had previously asked the question: "But does the oil flow in both directions at once in the Monarch and others?" I was simply saying that oil does not flow in two directions at once. If flows and displaces in one direction on the compression stroke, and then flows and displaces in the opposite direction on the rebound stroke. Regardless of mono or twin tube design.
-Darren
Anyone who knows me know what's coming... how can we make CSUs reliable enough to handle our riding and current geo? Or should we go to dual crowns for anything over 150mm? Personally, I'd like to see DC forks take over, I'm so sick of CSUs dying.
Maybe I've just had astronomically bad luck, but in 8 years I've gone through I think (edit, tallied them up) 7 CSUs from 3 brands. Sure, the first 4 of those were Fox, but I moved on to other brands and got more life, but the same problem . I now sell every single crown before it's out of warranty (puts on tinfoil hat after typing this). I'm just-a-guy, not at the pointy end, and ranged from 190-205 lbs kitted up, so within the bell curve on weight. This has to be getting expensive for brands, and it sucks for consumers.
What EXT is doing looks clever, but that still leaves the stanchion-CSU interface.
What's the solution to this all too common issue?
I have an Ohlins 34 with a 1 piece crown and steerer, not sure if they are still doing it on their more recent offerings?
The way ext does it is perhaps the best and still cost effective way compared to single piece csu. If you look at typical fork, overlap of steerer/crown is the same or less than overlap of crown/stanchions. And there are two stanchion tubes to spread the load(on 99% of forks). Can the fork creak in stanchion/crown joint? Sure, but it's lot less likely when they are bonded together properly in the first place. Short answer would be, yes, DC forks are the way to go if you are not in desperate need of barspins/tailwhips on your regular trail/ Enduro ride.
I want to take a moment to thank Darren from Push, who has a small business to run, for taking time to weigh in and educate mouth breathers like me about what's happening inside our suspension stuff that goes up-and-down. I've learned a ton from reading so far. Thanks, Darren!
One thing to point out about recent CSU problems, and I think I've posted about this before on tech rumors, is that they're really a function of bigger wheels for two reasons. First is that longer wheels and forks create more leverage at the CSU, and that's not a small factor. A 29" wheel and fork is a 40mm longer lever than an equivalent travel 26" wheel and fork. Second, that extra 40mm of stack height was a sticking point against the adoption of early 29ers, so (counterintuitively) manufacturers moved to shorter CSU assemblies with less steerer tube/crown overlap to reduce stack when they introduced 27.5 and 29" forks.
So at the same time that longer forks generated more leverage, they were also given shorter crowns to handle all that force. I remember way back in 2013 or so when Fox introduced the 27.5" and 29" 36 fork, they were bragging about how they shaved 10mm of stack height off the crown vs. the 26" version and saved a bunch of weight in the process 😬. I think we've been digging ourselves out of that hole ever since. Change is possible, though. I know the new 29" Zeb is 10 or 15mm taller than a 29" Lyrik of the same travel, and most of that is just due to crown height. Thank God. Smaller riders who don't want the extra front end height of a Zeb can fork-down to a 170mm Lyrik, and they'll probably benefit from a slightly flexier fork anyway. My two cents.
Interestingly, the stanchion/crown interface isn't constrained by stack height in the same way as the steerer tube/crown interface. They can make the crown taller or shorter around the stanchions and it just affects what shape and dimensions the lowers need to be cast in.
Yeah that sums it up - CSU's are always going to have the potential to creak when they are made by pressing thin alloy tubes in to alloy forgings. Going with less overlap at the same time as longer travel / larger wheels exacerbated the issue big time. Older 32mm forks probably creaked just as much but we couldn't hear it over the sound of chains and derailleurs banging on chainstays!
It could probably be reduced easily with a combination of a few mm stack height, a few grams of weight and a little bit more cost (for extra manufacturing processes) but people will absolutely not accept any of those things.
Supposedly the new Fox 38 with a taller crown is much more reliable, but that was coming from Fox themselves so not sure how much I would trust that.....
Rockshox filed a patent for stanchion surface treatments which would include texturing in the stanchion/crown interface and allow for the use of adhesives. That sounds like a potential cure, but is an extra step (and cost) in the manufacturing process. currently we just press smooth alloy tubes which don't give much space for a reliable adhesive to be use. Bearing in mind the ideal surface finish for a pressfit is VERY different to the ideal surface finish tube of a sliding on a teflon bushing!
For sure, there were so many industry guys giving really good info on MTBR suspension forum until a certain Kiwi with a hard on for Manitous (wonder who that could be) picked fights with all of them for no reason and it's a ghost town of it's former self. Darren was one of those guys who gave a lot of fantastic info. So cheers to him.
Hmmmm....Teamrobot is giving kudos? Has to be a prank!
Kidding aside....happy to participate.
https://www.intend-bc.com/products/stiffler/
The additional on cost to make the steerer/crown/stanchion more robust has surely got to outweigh the deluge of warranty claims for creaky CSU's. Both my Zebs are due a major service (the 23 needs it bushings resizing, but RS won't hold their hands up to that one and fix it!), whilst they are in, will have them pushed apart and glued back together.
Back in the day (when they had in-house suspension), Specialized played with bonding alloy tubes in alloy crowns.
It actually worked really well, passed all testing no problem. They were even ride tested after 100k+ cycles of abuse in the test lab and remained creak free and strong. Upper management decided to drop all in house suspension efforts, otherwise they would have gone into production.
One of the other things it allowed, which is still a major issues with current offering from RS and Fox that are pressed in, is that it allowed for perfect alignment of the stanchion tubes every time due to the bonding fixtures used.
It is currently quite common to see stanchion tubes that are 0.02"+ splayed out or in (or twisted) from the crown interface to the end of the tubes. It may seem small, but it is more than enough to make a fork bind in the bushings and feel like poo.
With good surface prep, correct bond gap/alignment design, and correct adhesive; bonding tubes into crowns is the way to go.
I never came across a creaky Blackbox carbon crown on the Revelation - though perhaps the small sample size influenced my perception, I only saw a handful of them. They appeared to be bonded.
Yeah I've seen an increase in mis-aligned CSU's in the last few years. One of several things that seemed like rushed production in the covid era. They're never been perfect but were at least close enough to not be noticeable. Never as bad as some of the old (08 era) marzocchis where I would get with 1 mm difference between the top and the bottom of the stanchions. People would always be looking at all kinds of tuning or mods to do on those forks and I was like my dude these are beyond help.......
Yeah the creaking is from the fretting that happens between 2 aluminium surfaces when they rub together so alloy-carbon wouldn't do it as much. Those forks however would leak air in to the steerer tube!
*edit - forgot to mention that the stanchion/crown overlap is limited by downtube clearance - as we went to wider hub spacing, larger stanchions and 29" wheels (steeper down tubes) the clearance can be super tight between the dials and the frames. In theory though as the steerer overlap increases you can add an equal amount of height to the stanchion interface
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