Suspension Component Technology/Functionality Discussion

Primoz wrote:

3D scanning might work (likely expensive), photogrammetry probably won't work as you need to look very deep into the air chamber to see the shape of...

3D scanning might work (likely expensive), photogrammetry probably won't work as you need to look very deep into the air chamber to see the shape of it, it's shiny and usually black, so I doubt you'll get any meaningful results from photogrammetry.

3D scanning is much more likely to work as it also projects (in IR) patterns onto the surface plus looks at the object using two cameras and the part has to be covered with something like TiO2 to be nice and matte to prevent reflections. But you're again back to square zero where you have to measure each and every shock option, it will more or less be a throw-away shock as it will be hard to properly clean the TiO2 from all the surfaces, etc.

It's a very expensive endeavour for something that a) is likely something the manufacturers already have and need to develop the platform correctly and b) would be very easy for the manufacturers to share and c) would not give anything away design wise as those who could realistically benefit from it, easily buy competitor products and analyse them (it's VERY hard to imagine the like of Fox, Rock Shox, Suntour and Manitou don't have 3D scnaning, dynos and other equipment in house and can't afford 20 to 30k to investigate competitor products once those come out).cha

FWIW, if data was shared, starting volumes of both positive and negative chambers, piston surface area and equalisation stroke point is what would be needed to fully model the shock for an enthusiast (spring stiffness wise).

ntm95 wrote:

I'd agree that it's going down the rabbit hole to actually measure volumes, shaft displacement, piston area, transfer port locations and attempt to extrapolate a curve.The...

I'd agree that it's going down the rabbit hole to actually measure volumes, shaft displacement, piston area, transfer port locations and attempt to extrapolate a curve.

The layman can suss out 90% of what they need by simply calculating compression ratio. But it's all arbitrary in most cases anyways when we are talking about applying this to a trail bike like a ripmo. An x2 is easy enough to tune, throw some volume spacers in it. Add some lsc, you'll be popping around like Jeff KW in no time.

 

boozed wrote:

In my ignorance I had assumed, apropos of nothing, that suspension tuners would have developed an heuristic for that by now, e.g. "above a certain leverage...

In my ignorance I had assumed, apropos of nothing, that suspension tuners would have developed an heuristic for that by now, e.g. "above a certain leverage ratio (or other characteristic) = Float X2, below it = Float X", or something along those lines, although I'm sure it isn't that simple.

How difficult is it to measure the chamber volumes when it's already open for service?  I imagine filling each chamber with an appropriate incompressible fluid, but I don't know enough about the insides of an air shock to know whether an "appropriate fluid" exists or if they'd tolerate that kind of thing in general.

TheSuspensionLabNZ wrote:

Yeah theres definitely some rough guidelines we pick up, but measuring air springs accurately is tricky so a lot of it comes down to rider feedback...

Yeah theres definitely some rough guidelines we pick up, but measuring air springs accurately is tricky so a lot of it comes down to rider feedback and trends as much as measuremements. And part of that for me is not being able to 100% confidently measure the full stroke of an air shock accurately across a range of pressures without a way to validate those tests. Each stroke shock and even trunnion and standard eyelets have different volumes so its a big task to collect data on all of them. 

Ive tried measuring a few different ways, all are pretty fiddly - you can fill it with oil or degreaser and weigh the shock before & after bit you still need to work our how much was in each chanber. The inside of the eyelets are awkward shapes so cant be directly measured either. It can be done, its just not always worth the amount of time it would take to work it out. Ive been playing with 3d scanning/photogrammetry and there is potential there for measuring things quite accurately though, so ill look at giving that a try for shock volume soon 

Primoz wrote:

3D scanning might work (likely expensive), photogrammetry probably won't work as you need to look very deep into the air chamber to see the shape of...

3D scanning might work (likely expensive), photogrammetry probably won't work as you need to look very deep into the air chamber to see the shape of it, it's shiny and usually black, so I doubt you'll get any meaningful results from photogrammetry.

3D scanning is much more likely to work as it also projects (in IR) patterns onto the surface plus looks at the object using two cameras and the part has to be covered with something like TiO2 to be nice and matte to prevent reflections. But you're again back to square zero where you have to measure each and every shock option, it will more or less be a throw-away shock as it will be hard to properly clean the TiO2 from all the surfaces, etc.

It's a very expensive endeavour for something that a) is likely something the manufacturers already have and need to develop the platform correctly and b) would be very easy for the manufacturers to share and c) would not give anything away design wise as those who could realistically benefit from it, easily buy competitor products and analyse them (it's VERY hard to imagine the like of Fox, Rock Shox, Suntour and Manitou don't have 3D scnaning, dynos and other equipment in house and can't afford 20 to 30k to investigate competitor products once those come out).cha

FWIW, if data was shared, starting volumes of both positive and negative chambers, piston surface area and equalisation stroke point is what would be needed to fully model the shock for an enthusiast (spring stiffness wise).

hamncheez2003 wrote:

Unrelated-- how do we feel about there Bartlett? There's a good deal on one. My two riding buddies had the MRP Ribbon and both were disappointing...

Unrelated-- how do we feel about there Bartlett? There's a good deal on one. My two riding buddies had the MRP Ribbon and both were disappointing to say the least,  but this was years ago.  IDK if MRP has updated their in house forks ever.

 

It would be nice to swap my 170mm fork to get 190mm with minimal AtC changes 

bikelurker wrote:

Just a quick question:

What does 'check tune' mean in Rock Shox rear shocks jargon?

 

boozed wrote:

In my ignorance I had assumed, apropos of nothing, that suspension tuners would have developed an heuristic for that by now, e.g. "above a certain leverage...

In my ignorance I had assumed, apropos of nothing, that suspension tuners would have developed an heuristic for that by now, e.g. "above a certain leverage ratio (or other characteristic) = Float X2, below it = Float X", or something along those lines, although I'm sure it isn't that simple.

How difficult is it to measure the chamber volumes when it's already open for service?  I imagine filling each chamber with an appropriate incompressible fluid, but I don't know enough about the insides of an air shock to know whether an "appropriate fluid" exists or if they'd tolerate that kind of thing in general.

TheSuspensionLabNZ wrote:

Yeah theres definitely some rough guidelines we pick up, but measuring air springs accurately is tricky so a lot of it comes down to rider feedback...

Yeah theres definitely some rough guidelines we pick up, but measuring air springs accurately is tricky so a lot of it comes down to rider feedback and trends as much as measuremements. And part of that for me is not being able to 100% confidently measure the full stroke of an air shock accurately across a range of pressures without a way to validate those tests. Each stroke shock and even trunnion and standard eyelets have different volumes so its a big task to collect data on all of them. 

Ive tried measuring a few different ways, all are pretty fiddly - you can fill it with oil or degreaser and weigh the shock before & after bit you still need to work our how much was in each chanber. The inside of the eyelets are awkward shapes so cant be directly measured either. It can be done, its just not always worth the amount of time it would take to work it out. Ive been playing with 3d scanning/photogrammetry and there is potential there for measuring things quite accurately though, so ill look at giving that a try for shock volume soon 

FrontRangeFriend wrote:

I’ve always been suspicious that changing shock stroke changed the air volume on my X2. I extended the stroke from 62.5 to 65 and it felt softer...

I’ve always been suspicious that changing shock stroke changed the air volume on my X2. 

I extended the stroke from 62.5 to 65 and it felt softer even at the same sag (by distance in mm, not by %). I put a volume spacer in and it felt similar to the prior stroke.

Primoz wrote:

What exactly does the compression ratio give you? 

TheSuspensionLabNZ wrote:

Yeah theres definitely some rough guidelines we pick up, but measuring air springs accurately is tricky so a lot of it comes down to rider feedback...

Yeah theres definitely some rough guidelines we pick up, but measuring air springs accurately is tricky so a lot of it comes down to rider feedback and trends as much as measuremements. And part of that for me is not being able to 100% confidently measure the full stroke of an air shock accurately across a range of pressures without a way to validate those tests. Each stroke shock and even trunnion and standard eyelets have different volumes so its a big task to collect data on all of them. 

Ive tried measuring a few different ways, all are pretty fiddly - you can fill it with oil or degreaser and weigh the shock before & after bit you still need to work our how much was in each chanber. The inside of the eyelets are awkward shapes so cant be directly measured either. It can be done, its just not always worth the amount of time it would take to work it out. Ive been playing with 3d scanning/photogrammetry and there is potential there for measuring things quite accurately though, so ill look at giving that a try for shock volume soon 

Primoz wrote:

3D scanning might work (likely expensive), photogrammetry probably won't work as you need to look very deep into the air chamber to see the shape of...

3D scanning might work (likely expensive), photogrammetry probably won't work as you need to look very deep into the air chamber to see the shape of it, it's shiny and usually black, so I doubt you'll get any meaningful results from photogrammetry.

3D scanning is much more likely to work as it also projects (in IR) patterns onto the surface plus looks at the object using two cameras and the part has to be covered with something like TiO2 to be nice and matte to prevent reflections. But you're again back to square zero where you have to measure each and every shock option, it will more or less be a throw-away shock as it will be hard to properly clean the TiO2 from all the surfaces, etc.

It's a very expensive endeavour for something that a) is likely something the manufacturers already have and need to develop the platform correctly and b) would be very easy for the manufacturers to share and c) would not give anything away design wise as those who could realistically benefit from it, easily buy competitor products and analyse them (it's VERY hard to imagine the like of Fox, Rock Shox, Suntour and Manitou don't have 3D scnaning, dynos and other equipment in house and can't afford 20 to 30k to investigate competitor products once those come out).cha

FWIW, if data was shared, starting volumes of both positive and negative chambers, piston surface area and equalisation stroke point is what would be needed to fully model the shock for an enthusiast (spring stiffness wise).

TheSuspensionLabNZ wrote:

I wouldn't have mentioned photogrammetry if it wasn't something I was already playing with......this was done with a smartphone and a relatively cheap app....that shaft is...

I wouldn't have mentioned photogrammetry if it wasn't something I was already playing with......this was done with a smartphone and a relatively cheap app....that shaft is supposed to be 14.00mm btw 

Primoz wrote:

What exactly does the compression ratio give you? 

ntm95 wrote:

Average spring curve. 

TheSuspensionLabNZ wrote:

I wouldn't have mentioned photogrammetry if it wasn't something I was already playing with......this was done with a smartphone and a relatively cheap app....that shaft is...

I wouldn't have mentioned photogrammetry if it wasn't something I was already playing with......this was done with a smartphone and a relatively cheap app....that shaft is supposed to be 14.00mm btw 

Primoz wrote:

What exactly does the compression ratio give you? 

ntm95 wrote:

Average spring curve. 

Primoz wrote:

How? 

HexonJuan wrote:

OK nerds, have a live one for you. Am I nuts thinking it'd be pretty freaking sweet for sus co's to specify what their stock air...

OK nerds, have a live one for you. Am I nuts thinking it'd be pretty freaking sweet for sus co's to specify what their stock air spring volumes are for forks and dampers? I posit after a bit of a lengthy chat with a pal about why the X2 on his V2 Ripmo isn't the greatest choice for the platform and the bike would be better suited with a smaller spring volume, citing the playfulness of my V3 Rip. Bear in mind he's had the bike since new and never got used to the plow feel, preferring a spunkier ride. I thought it'd be sweet if we had access to that info as well as the piston diameters for those of us who like to do the math so we can better understand and show the rate change effects. 

So, silly or no?

Primoz wrote:

3D scanning might work (likely expensive), photogrammetry probably won't work as you need to look very deep into the air chamber to see the shape of...

3D scanning might work (likely expensive), photogrammetry probably won't work as you need to look very deep into the air chamber to see the shape of it, it's shiny and usually black, so I doubt you'll get any meaningful results from photogrammetry.

3D scanning is much more likely to work as it also projects (in IR) patterns onto the surface plus looks at the object using two cameras and the part has to be covered with something like TiO2 to be nice and matte to prevent reflections. But you're again back to square zero where you have to measure each and every shock option, it will more or less be a throw-away shock as it will be hard to properly clean the TiO2 from all the surfaces, etc.

It's a very expensive endeavour for something that a) is likely something the manufacturers already have and need to develop the platform correctly and b) would be very easy for the manufacturers to share and c) would not give anything away design wise as those who could realistically benefit from it, easily buy competitor products and analyse them (it's VERY hard to imagine the like of Fox, Rock Shox, Suntour and Manitou don't have 3D scnaning, dynos and other equipment in house and can't afford 20 to 30k to investigate competitor products once those come out).cha

FWIW, if data was shared, starting volumes of both positive and negative chambers, piston surface area and equalisation stroke point is what would be needed to fully model the shock for an enthusiast (spring stiffness wise).

TheSuspensionLabNZ wrote:

I wouldn't have mentioned photogrammetry if it wasn't something I was already playing with......this was done with a smartphone and a relatively cheap app....that shaft is...

I wouldn't have mentioned photogrammetry if it wasn't something I was already playing with......this was done with a smartphone and a relatively cheap app....that shaft is supposed to be 14.00mm btw 

Primoz wrote:

This is very different to trying to scan the insides of an aircan (or aircan). The problem is the flare right above the outer sealhead if...

This is very different to trying to scan the insides of an aircan (or aircan). The problem is the flare right above the outer sealhead if it's present. And the outside technically doesn't help as you don't know the wall thickness. 

Unless you cut it in half. 

TheSuspensionLabNZ wrote:

I wouldn't have mentioned photogrammetry if it wasn't something I was already playing with......this was done with a smartphone and a relatively cheap app....that shaft is...

I wouldn't have mentioned photogrammetry if it wasn't something I was already playing with......this was done with a smartphone and a relatively cheap app....that shaft is supposed to be 14.00mm btw 

CascadeComponents wrote:

What app is that? All the phone based ones I've messed with have been pretty bad so I gave up on them.As far as figuring out...

What app is that? All the phone based ones I've messed with have been pretty bad so I gave up on them.

As far as figuring out spring curves, it would probably be easier and more accurate to measure the shock's actual spring curve and then fit it to an equation to approximate the curve at any pressure. If you know shock stroke used and initial positive pressure, you only have to back out initial negative pressure, negative piston area, positive piston area, initial negative air volume, and positive air volume. Pick five data points and that's a system of equations you can solve.

ntm95 wrote:

Average spring curve. 

Primoz wrote:

How? 

ntm95 wrote:

Nothing fancy, or particularly useful. Simply gives you an idea of spring rate progression vs a linear rate progression.In the context of the OP, they're looking...

Nothing fancy, or particularly useful. Simply gives you an idea of spring rate progression vs a linear rate progression.

In the context of the OP, they're looking for "pop", as in a higher progression rate/compression ratio. That data might be useful to them in so far as to compare an x2 to something like a float x, in order to isolate spring performance vs having more valving in the x2. Case in point, ibis uses extremely light valving for the most part, I suspect in the OP's case, the tune is the major factor creating a difference between the two bikes, not necessarily the air spring volumes. Likely the v3 ripmo is on an ibis tune, and the v2 is an off the shelf mid tune x2. Comparing the two compression ratios would give him an idea. Of course the sensible thing is to simply compare the tunes.

iceman2058 wrote:

Anti-dive device for the fork...I wonder how this rides. It has to add some harshness under braking, and I'm sure the way the bike reacts under...

Anti-dive device for the fork...I wonder how this rides. It has to add some harshness under braking, and I'm sure the way the bike reacts under braking would take some getting used to as well, but still an interesting experiment:

HexonJuan wrote:

OK nerds, have a live one for you. Am I nuts thinking it'd be pretty freaking sweet for sus co's to specify what their stock air...

OK nerds, have a live one for you. Am I nuts thinking it'd be pretty freaking sweet for sus co's to specify what their stock air spring volumes are for forks and dampers? I posit after a bit of a lengthy chat with a pal about why the X2 on his V2 Ripmo isn't the greatest choice for the platform and the bike would be better suited with a smaller spring volume, citing the playfulness of my V3 Rip. Bear in mind he's had the bike since new and never got used to the plow feel, preferring a spunkier ride. I thought it'd be sweet if we had access to that info as well as the piston diameters for those of us who like to do the math so we can better understand and show the rate change effects. 

So, silly or no?

TEAMROBOT wrote:

I think that information is useful, but in a limited sense. Positive air spring volume is one number that's part of several other ratios that determine...

I think that information is useful, but in a limited sense. Positive air spring volume is one number that's part of several other ratios that determine spring rate, like positive to negative volume ratio (e.g. MegNeg) and positive volume to air shaft displacement ratio (e.g. new Boxxer with a smaller seal head, requiring way higher pressures to create a more linear feel). You could be looking at two shocks with similar positive spring volumes that had very different spring rate curves depending on some of those other factors.

Primoz wrote:

The compression ratio would be a very good indicator of shock performance if it only had the positive chamber. With the negative chamber volume, piston area...

The compression ratio would be a very good indicator of shock performance if it only had the positive chamber. With the negative chamber volume, piston area and equalisation point playing a role it doesn't give much usable data by it's own. 

The shockwiz measures the compression ratio to know roughly where in the travel it sits by measuring the pressure. The keyword is roughly though. 

AndehM wrote:

Got it, seems pretty straightforward.  Looks like a fun weekend project.  I'll probably split the difference on the compression side, putting the spacer in between #2...

Got it, seems pretty straightforward.  Looks like a fun weekend project.  I'll probably split the difference on the compression side, putting the spacer in between #2 & #3, seeing as how I'm of the opinion some damping is better than none.  Thank you so much for your help.

AndehM wrote:

Got it, seems pretty straightforward.  Looks like a fun weekend project.  I'll probably split the difference on the compression side, putting the spacer in between #2...

Got it, seems pretty straightforward.  Looks like a fun weekend project.  I'll probably split the difference on the compression side, putting the spacer in between #2 & #3, seeing as how I'm of the opinion some damping is better than none.  Thank you so much for your help.

descendnow wrote:

Hey, 

How did it go for you? What did you do in the end? Let us know  

Cheers 

TheSuspensionLabNZ wrote:

The new 3.1 manual includes a light rebound tune which works for 3.0 dampers as well, but I would probably remove 1 more shim than what...

The new 3.1 manual includes a light rebound tune which works for 3.0 dampers as well, but I would probably remove 1 more shim than what is suggested in the stack for a kid that light

AndehM wrote:

Thanks, looking at the manual now, I must have remembered the Comp tune.  So you're suggesting taking the "Light" tune stack of 14(0.15)x3 - 7(0.3)x4 -...

Thanks, looking at the manual now, I must have remembered the Comp tune.  So you're suggesting taking the "Light" tune stack of 14(0.15)x3 - 7(0.3)x4 - 14(0.1)x1 (all 5mm ID) and dropping that to 14(0.15)x3 - 7(0.3)x4?  Eliminating the 14mm OD 0.1mm thick single shim?  

Don't I need to maintain the same overall stack height (1.75mm)?  If I'm doing my math right, what I could do is eliminate 2 of the 14mm 0.15 thick shims and add 1 7mm 0.3 thick spacer.

Assuming what I'm thinking about the stack height needing to remain the same, I don't see any way to reduce the Comp "Standard" tune without sourcing custom spacers.

TheSuspensionLabNZ wrote:

The 14x0.1 is the check shim so leave that in - I would instead take the original medium tune (3 x 14mm OD shims and 2x...

The 14x0.1 is the check shim so leave that in - I would instead take the original medium tune (3 x 14mm OD shims and 2x 12mm x  0.15mm shims) and leave 1 x 14 x 0.15 and 1 x 12 x 0.15. Stack height I don't think is mega critical but it is good practice so what you can do is place the spares between spacer shims where they will do nothing ie-

Piston

14 x 0.15

12 x 0.15

7 x 0.3 - spacer

14 x 0.15

14 x 0.15

12 x 0.15

7 x 0.3 -spacer

7 x 0.3 -spacer

14 x 0.1

 

the 0.3 is thick enough that the shims will never flex far enough to touch the spares. On the compression piston, you can move a spacer shim between the face shims somewhere to reduce the preload - between the first and second reduces the compression damping to hardly anything, or moving it up in the stack retains a little bit of damping if you need it at some point. You need 1 shim in contact with the piston to maintain a seal. Or you can remove face shims and put them behind the spacers again, but I find reducing the preload is pretty effective for very light riders

ryosukekimura wrote:

Friend here. This was for my son. We've spent more time bracketing. Swapped the rear shock to Vivid etc.I got a 3.1 upgrade kit. I'd appreciate...

Friend here. This was for my son. We've spent more time bracketing. Swapped the rear shock to Vivid etc.
I got a 3.1 upgrade kit. I'd appreciate it if you could give us your suggestions based on the updated setup.

Rider: 9 years old: 142cm /  4'8"
Riding Style: https://www.instagram.com/reel/DOFnQTdjpPm/?igsh=NTc4MTIwNjQ2YQ%3D%3D
Rider Weight: 36kg / 80lbs with full riding gear
Bike: 2024 Santa Cruz Bronson V4.1 XS (14.35kg / 31.6 lbs)

Shock: Vivid RS-VIIVD-ULT-C1
 - Rebound Tune: R25
 - Compression Tune: C34
 - Volume Reducer: 1 Token
 - PSI: 72psi
 - Rebound: fully Open
 - HSC: 0
 - LSC: 0
 - HBO: -1

He uses almost all travel without a harsh bottom out. Rebound could be faster, but it's not excessively slow like he was on stock Super Deluxe. He struggled to use full travel, about 80% ish, with Super Deluxe with 0 tokens. He was asking to run higher PSI to get more pop but it makes it even harder to use more travel. Everything was fixed after we swapped it to Vivid. 

So his fork is the next thing to be dialed.

Current Fork Setup
Fork: Lyrik Select+ FS-LYRK-SELP-D1
Damper: Charger 3 RC2
Token: Installed MRP Noken
PSI: 30psi
Rebound: Fully open
HSC: -2
LSC:- 7 (Fully open)

He started using a similar fork travel as I do after installing MRP Noken, however, the rebound (especially after the deep compression) seems slow.

We got the 3.1 upgrade kit. I'd appreciate if you could share some recommended shim setup for him.
I just want to make sure we don't make it too light for what he does now and what he'll do in the future.

He rides at the park and likes to jump and hit drops, etc.
The picture is after we hit the local trails at the speed. The trail doesn't have huge drops but has some jumps, step down, and high compression berms.











 

AndehM wrote:

Thanks, looking at the manual now, I must have remembered the Comp tune.  So you're suggesting taking the "Light" tune stack of 14(0.15)x3 - 7(0.3)x4 -...

Thanks, looking at the manual now, I must have remembered the Comp tune.  So you're suggesting taking the "Light" tune stack of 14(0.15)x3 - 7(0.3)x4 - 14(0.1)x1 (all 5mm ID) and dropping that to 14(0.15)x3 - 7(0.3)x4?  Eliminating the 14mm OD 0.1mm thick single shim?  

Don't I need to maintain the same overall stack height (1.75mm)?  If I'm doing my math right, what I could do is eliminate 2 of the 14mm 0.15 thick shims and add 1 7mm 0.3 thick spacer.

Assuming what I'm thinking about the stack height needing to remain the same, I don't see any way to reduce the Comp "Standard" tune without sourcing custom spacers.

TheSuspensionLabNZ wrote:

The 14x0.1 is the check shim so leave that in - I would instead take the original medium tune (3 x 14mm OD shims and 2x...

The 14x0.1 is the check shim so leave that in - I would instead take the original medium tune (3 x 14mm OD shims and 2x 12mm x  0.15mm shims) and leave 1 x 14 x 0.15 and 1 x 12 x 0.15. Stack height I don't think is mega critical but it is good practice so what you can do is place the spares between spacer shims where they will do nothing ie-

Piston

14 x 0.15

12 x 0.15

7 x 0.3 - spacer

14 x 0.15

14 x 0.15

12 x 0.15

7 x 0.3 -spacer

7 x 0.3 -spacer

14 x 0.1

 

the 0.3 is thick enough that the shims will never flex far enough to touch the spares. On the compression piston, you can move a spacer shim between the face shims somewhere to reduce the preload - between the first and second reduces the compression damping to hardly anything, or moving it up in the stack retains a little bit of damping if you need it at some point. You need 1 shim in contact with the piston to maintain a seal. Or you can remove face shims and put them behind the spacers again, but I find reducing the preload is pretty effective for very light riders

ryosukekimura wrote:

Friend here. This was for my son. We've spent more time bracketing. Swapped the rear shock to Vivid etc.I got a 3.1 upgrade kit. I'd appreciate...

Friend here. This was for my son. We've spent more time bracketing. Swapped the rear shock to Vivid etc.
I got a 3.1 upgrade kit. I'd appreciate it if you could give us your suggestions based on the updated setup.

Rider: 9 years old: 142cm /  4'8"
Riding Style: https://www.instagram.com/reel/DOFnQTdjpPm/?igsh=NTc4MTIwNjQ2YQ%3D%3D
Rider Weight: 36kg / 80lbs with full riding gear
Bike: 2024 Santa Cruz Bronson V4.1 XS (14.35kg / 31.6 lbs)

Shock: Vivid RS-VIIVD-ULT-C1
 - Rebound Tune: R25
 - Compression Tune: C34
 - Volume Reducer: 1 Token
 - PSI: 72psi
 - Rebound: fully Open
 - HSC: 0
 - LSC: 0
 - HBO: -1

He uses almost all travel without a harsh bottom out. Rebound could be faster, but it's not excessively slow like he was on stock Super Deluxe. He struggled to use full travel, about 80% ish, with Super Deluxe with 0 tokens. He was asking to run higher PSI to get more pop but it makes it even harder to use more travel. Everything was fixed after we swapped it to Vivid. 

So his fork is the next thing to be dialed.

Current Fork Setup
Fork: Lyrik Select+ FS-LYRK-SELP-D1
Damper: Charger 3 RC2
Token: Installed MRP Noken
PSI: 30psi
Rebound: Fully open
HSC: -2
LSC:- 7 (Fully open)

He started using a similar fork travel as I do after installing MRP Noken, however, the rebound (especially after the deep compression) seems slow.

We got the 3.1 upgrade kit. I'd appreciate if you could share some recommended shim setup for him.
I just want to make sure we don't make it too light for what he does now and what he'll do in the future.

He rides at the park and likes to jump and hit drops, etc.
The picture is after we hit the local trails at the speed. The trail doesn't have huge drops but has some jumps, step down, and high compression berms.











 

TheSuspensionLabNZ wrote:

The 14x0.1 is the check shim so leave that in - I would instead take the original medium tune (3 x 14mm OD shims and 2x...

The 14x0.1 is the check shim so leave that in - I would instead take the original medium tune (3 x 14mm OD shims and 2x 12mm x  0.15mm shims) and leave 1 x 14 x 0.15 and 1 x 12 x 0.15. Stack height I don't think is mega critical but it is good practice so what you can do is place the spares between spacer shims where they will do nothing ie-

Piston

14 x 0.15

12 x 0.15

7 x 0.3 - spacer

14 x 0.15

14 x 0.15

12 x 0.15

7 x 0.3 -spacer

7 x 0.3 -spacer

14 x 0.1

 

the 0.3 is thick enough that the shims will never flex far enough to touch the spares. On the compression piston, you can move a spacer shim between the face shims somewhere to reduce the preload - between the first and second reduces the compression damping to hardly anything, or moving it up in the stack retains a little bit of damping if you need it at some point. You need 1 shim in contact with the piston to maintain a seal. Or you can remove face shims and put them behind the spacers again, but I find reducing the preload is pretty effective for very light riders

ryosukekimura wrote:

Friend here. This was for my son. We've spent more time bracketing. Swapped the rear shock to Vivid etc.I got a 3.1 upgrade kit. I'd appreciate...

Friend here. This was for my son. We've spent more time bracketing. Swapped the rear shock to Vivid etc.
I got a 3.1 upgrade kit. I'd appreciate it if you could give us your suggestions based on the updated setup.

Rider: 9 years old: 142cm /  4'8"
Riding Style: https://www.instagram.com/reel/DOFnQTdjpPm/?igsh=NTc4MTIwNjQ2YQ%3D%3D
Rider Weight: 36kg / 80lbs with full riding gear
Bike: 2024 Santa Cruz Bronson V4.1 XS (14.35kg / 31.6 lbs)

Shock: Vivid RS-VIIVD-ULT-C1
 - Rebound Tune: R25
 - Compression Tune: C34
 - Volume Reducer: 1 Token
 - PSI: 72psi
 - Rebound: fully Open
 - HSC: 0
 - LSC: 0
 - HBO: -1

He uses almost all travel without a harsh bottom out. Rebound could be faster, but it's not excessively slow like he was on stock Super Deluxe. He struggled to use full travel, about 80% ish, with Super Deluxe with 0 tokens. He was asking to run higher PSI to get more pop but it makes it even harder to use more travel. Everything was fixed after we swapped it to Vivid. 

So his fork is the next thing to be dialed.

Current Fork Setup
Fork: Lyrik Select+ FS-LYRK-SELP-D1
Damper: Charger 3 RC2
Token: Installed MRP Noken
PSI: 30psi
Rebound: Fully open
HSC: -2
LSC:- 7 (Fully open)

He started using a similar fork travel as I do after installing MRP Noken, however, the rebound (especially after the deep compression) seems slow.

We got the 3.1 upgrade kit. I'd appreciate if you could share some recommended shim setup for him.
I just want to make sure we don't make it too light for what he does now and what he'll do in the future.

He rides at the park and likes to jump and hit drops, etc.
The picture is after we hit the local trails at the speed. The trail doesn't have huge drops but has some jumps, step down, and high compression berms.











 

TheSuspensionLabNZ wrote:

Ok a few thoughts -Friction your biggest enememy, especially at this weight range and will add a significant amount of force slowing down rebound and preventing...

Ok a few thoughts -

Friction your biggest enememy, especially at this weight range and will add a significant amount of force slowing down rebound and preventing it from getting fulll travel. Things like having the bushings sized go a long way here, also make sure the air spring is lubricated and no one wiped all the grease out. 

In saying that, dont look at getting full travel as a target - once things are running properly you might also start using more stroke but its not an issue to normally use 80-90% . All set ups need some kind of compromise and personally this is the first thing i would let go of.

The spring might be a little soft at 30psi, potentially 35 would be more inline with pressures at higher weights. 

The slow rebound is probably a combination of low pressure and friction - you can also try very light oil with the tune from above, the stock is 7wt but I would at least use the rs/maxima 3wt or even something like the fox 1.5wt dropper fluid. 

That tune should be ok up to around 45-50kg, maybe a little more but kids grow fast and will often need a new tune very soon anyway

ryosukekimura wrote:

Thank you for your insights. Yes, he shouldn't use full fork travel at the local trail without huge drops. So in terms of travel usage, it...

Thank you for your insights. Yes, he shouldn't use full fork travel at the local trail without huge drops. So in terms of travel usage, it looks OK for now.

I got a SKF seal, and my friend plans to burnish the fork to reduce friction.

I'm slightly concerned about running a super light compression tune, as I heard Jordi at Fox say that compression is more terrain- and rider skill/style-dependent than weight-dependent, unlike rebound. I just want to make sure he'll have enough compression and rebound to dial in for bike park riding, like big drops.

Should we run your suggested tune with 3wt oil, or should we run a stock-lighter tune with 3wt oil?

Thank you so much for your knowledge and insights. 


Reference:
Max suggested height is 5'1" and the average weight is around 46 - 56 kg.



 

TheSuspensionLabNZ wrote:

I'll try to keep it general to stay relevant to the thread,  - Even using that much travel on drops might be fine, or at least don't...

I'll try to keep it general to stay relevant to the thread,  - 

Even using that much travel on drops might be fine, or at least don't rule out running slightly higher pressure still.

Friction & spring are the 2 most important things (after tyres) so don't stress about the damper until those are fully optimised. If there is too much friction or the spring is too soft then there won't be much difference between those 2 tunes

I can't speak for Jordi but my thoughts would be a) the Charger 3.1 is very different to grip 2 or X2 in terms of damping levels, so while a grip2 damper is fine for very light riders, the 3.1 does have limits below a certain weight so is something worth tuning for light riders. b) the difference in optimum damping levels is quite small between something like a 60kg adult and 90kg adult so preference or speed is as big of a factor as weight. eg a top elite rider will have a stiffer spring and slightly more damping which will combine to feel very stiff to an average rider but each variable is only slightly higher on its own. But when you get down to light riders the proportion of friction is huge - ie there could be 10kg of total friction in a fork which is important but less noticeable to a 90kg rider than a 40kg rider. Friction is a form of damping so we often need to reduce compression damping more than what would theoretically be ideal to compensate for that. 

Each production damper from brands like Fox and Rockshox have certain compromises - they will almost never be perfect for anyone so you will be trading something off no matter what you do with it. It's tough to predict the perfect setting for anyone so you often need a few attempts, therefore my suggestions, depending on time/patience/budget and what you have available locally would be - 

Start by dialling in the chassis and air spring only - if it still doesn't feel right then try another damper tune

Do the chassis & air spring along with the soft tune (removing preload) - you might need to add some damping back but its basically a coin toss as to which you do first.  I usually prefer to make a huge change first then dial it back so by going to a very soft tune the outcomes are either  

a) it feels great

b) it still feels too stiff which means there is either still friction or you have reached the limit of the fork  

c) it is too soft and you can step back to halfway between and it should be pretty good. If you only go to the slightly lighter tune to begin with and it feels better, but could still be improved you actually don't know if you should go softer or firmer from there. 

 

last option - give a bunch of money to a good suspension shop to do it all properly and can take the time to work out the best options. If you are doing it yourself theres not really a quick way to the best setting so there will always be some trial and error. Normally the exact tune I would personally install also depends on me doing the rest of the fork too - everyone works different so if I knew the chassis was perfectly optimised (maybe using a coil spring too) then I would potentially use a bit more damping, but if in doubt I would oitherwise err on the side of slightly softer first.

 

TheSuspensionLabNZ wrote:

I'll try to keep it general to stay relevant to the thread,  - Even using that much travel on drops might be fine, or at least don't...

I'll try to keep it general to stay relevant to the thread,  - 

Even using that much travel on drops might be fine, or at least don't rule out running slightly higher pressure still.

Friction & spring are the 2 most important things (after tyres) so don't stress about the damper until those are fully optimised. If there is too much friction or the spring is too soft then there won't be much difference between those 2 tunes

I can't speak for Jordi but my thoughts would be a) the Charger 3.1 is very different to grip 2 or X2 in terms of damping levels, so while a grip2 damper is fine for very light riders, the 3.1 does have limits below a certain weight so is something worth tuning for light riders. b) the difference in optimum damping levels is quite small between something like a 60kg adult and 90kg adult so preference or speed is as big of a factor as weight. eg a top elite rider will have a stiffer spring and slightly more damping which will combine to feel very stiff to an average rider but each variable is only slightly higher on its own. But when you get down to light riders the proportion of friction is huge - ie there could be 10kg of total friction in a fork which is important but less noticeable to a 90kg rider than a 40kg rider. Friction is a form of damping so we often need to reduce compression damping more than what would theoretically be ideal to compensate for that. 

Each production damper from brands like Fox and Rockshox have certain compromises - they will almost never be perfect for anyone so you will be trading something off no matter what you do with it. It's tough to predict the perfect setting for anyone so you often need a few attempts, therefore my suggestions, depending on time/patience/budget and what you have available locally would be - 

Start by dialling in the chassis and air spring only - if it still doesn't feel right then try another damper tune

Do the chassis & air spring along with the soft tune (removing preload) - you might need to add some damping back but its basically a coin toss as to which you do first.  I usually prefer to make a huge change first then dial it back so by going to a very soft tune the outcomes are either  

a) it feels great

b) it still feels too stiff which means there is either still friction or you have reached the limit of the fork  

c) it is too soft and you can step back to halfway between and it should be pretty good. If you only go to the slightly lighter tune to begin with and it feels better, but could still be improved you actually don't know if you should go softer or firmer from there. 

 

last option - give a bunch of money to a good suspension shop to do it all properly and can take the time to work out the best options. If you are doing it yourself theres not really a quick way to the best setting so there will always be some trial and error. Normally the exact tune I would personally install also depends on me doing the rest of the fork too - everyone works different so if I knew the chassis was perfectly optimised (maybe using a coil spring too) then I would potentially use a bit more damping, but if in doubt I would oitherwise err on the side of slightly softer first.

 

TEAMROBOT wrote:

Here's a dumb question: How difficult, expensive, or dangerous would it be to use a machine (I assume a lathe) to cut off material from a...

Here's a dumb question: How difficult, expensive, or dangerous would it be to use a machine (I assume a lathe) to cut off material from a coil spring and tune spring rate?

I remember seeing this once from (I think a Kiwi) racer or tuning shop in a WC DH bike check, where a stock steel coil had a constant diameter of the coil shaved off to dial in an exact spring rate that was in between the manufacturer's 50-pound range.

This sort of thing could be helpful for a super light 80-pound rider who's looking to reduce friction (i.e. using a Smashpot in a Zeb where you might need to go lower than the lowest 25 pound spring), or for someone who buys a Marzocchi coil sprung Z1 that only offers four spring rates, creating big gaps between spring rates.

I imagine you'd need to insert something in the center of the spring to perfectly center it and stabilize it on the lathe, but once you're centered and stabilized... start shaving away, amiright?

TheSuspensionLabNZ wrote:

I'll try to keep it general to stay relevant to the thread,  - Even using that much travel on drops might be fine, or at least don't...

I'll try to keep it general to stay relevant to the thread,  - 

Even using that much travel on drops might be fine, or at least don't rule out running slightly higher pressure still.

Friction & spring are the 2 most important things (after tyres) so don't stress about the damper until those are fully optimised. If there is too much friction or the spring is too soft then there won't be much difference between those 2 tunes

I can't speak for Jordi but my thoughts would be a) the Charger 3.1 is very different to grip 2 or X2 in terms of damping levels, so while a grip2 damper is fine for very light riders, the 3.1 does have limits below a certain weight so is something worth tuning for light riders. b) the difference in optimum damping levels is quite small between something like a 60kg adult and 90kg adult so preference or speed is as big of a factor as weight. eg a top elite rider will have a stiffer spring and slightly more damping which will combine to feel very stiff to an average rider but each variable is only slightly higher on its own. But when you get down to light riders the proportion of friction is huge - ie there could be 10kg of total friction in a fork which is important but less noticeable to a 90kg rider than a 40kg rider. Friction is a form of damping so we often need to reduce compression damping more than what would theoretically be ideal to compensate for that. 

Each production damper from brands like Fox and Rockshox have certain compromises - they will almost never be perfect for anyone so you will be trading something off no matter what you do with it. It's tough to predict the perfect setting for anyone so you often need a few attempts, therefore my suggestions, depending on time/patience/budget and what you have available locally would be - 

Start by dialling in the chassis and air spring only - if it still doesn't feel right then try another damper tune

Do the chassis & air spring along with the soft tune (removing preload) - you might need to add some damping back but its basically a coin toss as to which you do first.  I usually prefer to make a huge change first then dial it back so by going to a very soft tune the outcomes are either  

a) it feels great

b) it still feels too stiff which means there is either still friction or you have reached the limit of the fork  

c) it is too soft and you can step back to halfway between and it should be pretty good. If you only go to the slightly lighter tune to begin with and it feels better, but could still be improved you actually don't know if you should go softer or firmer from there. 

 

last option - give a bunch of money to a good suspension shop to do it all properly and can take the time to work out the best options. If you are doing it yourself theres not really a quick way to the best setting so there will always be some trial and error. Normally the exact tune I would personally install also depends on me doing the rest of the fork too - everyone works different so if I knew the chassis was perfectly optimised (maybe using a coil spring too) then I would potentially use a bit more damping, but if in doubt I would oitherwise err on the side of slightly softer first.

 

TEAMROBOT wrote:

Here's a dumb question: How difficult, expensive, or dangerous would it be to use a machine (I assume a lathe) to cut off material from a...

Here's a dumb question: How difficult, expensive, or dangerous would it be to use a machine (I assume a lathe) to cut off material from a coil spring and tune spring rate?

I remember seeing this once from (I think a Kiwi) racer or tuning shop in a WC DH bike check, where a stock steel coil had a constant diameter of the coil shaved off to dial in an exact spring rate that was in between the manufacturer's 50-pound range.

This sort of thing could be helpful for a super light 80-pound rider who's looking to reduce friction (i.e. using a Smashpot in a Zeb where you might need to go lower than the lowest 25 pound spring), or for someone who buys a Marzocchi coil sprung Z1 that only offers four spring rates, creating big gaps between spring rates.

I imagine you'd need to insert something in the center of the spring to perfectly center it and stabilize it on the lathe, but once you're centered and stabilized... start shaving away, amiright?