The Tuesday Tune Ep 5: Low- and High-Speed Damping - Video

 Thanks, we try

 @VorsprungSuspension: Is it wrong to think about suspension settings as tools to adjust steering geometry? In my moto and road race motorcycling days, I would always tune suspension to get the desired turning attributes I am looking for... Balancing act between "knifing" (twitchy over steer) to "plowing" (stable under steer). If I I'm losing speed in a critical turn because the bike runs wide and wont finish a turn, either increase rebound or decrease HS Comp in front and conversely, reduce rebound or increase HS comp in the rear to effectively increase HTA?? That's what's works for me. The decision to adjust rebound or compression is the tough one that I struggle with.. Any insight?

 @ErnieK: it's really critical to steering on any motorised vehicle for sure, because it massively affects weight transfer due to the rigid sprung mass. It does have an effect, but to a much lesser extent on mountain bikes because the rider is able to shift 80-90% of the sprung mass a huge amount backwards or forwards relative to the wheelbase and have a larger effect on both geometry and tyre load than the suspension alone can create.

 Thanks for the kind words!

 @VorsprungSuspension same here - was watching it today and it really helped me understand why I like some forks and do not get along with otheres that well

 Usually you want to dial your HSC then your LSC.

 We'll be looking at that next week

 @VorsprungSuspension: Seriously looking forward to that, great videos Steve. I've had CCDB coil CS for a week now and got it set up with no LSC as I like very supple small bump sensitivity and about 2.5 turns out of 4 for HSC. I've got the rebound slow on both circuits so I don't get bucked if I do find myself jumping and so that the bike doesn't feel like a pogo stick on the small stuff. I weigh about 134 lbs and have a 300lb coil at 20% sag on a transition if that helps clarify anything and would love a simple yes/no, you've got that sounding really well set up/no, it sounds wrong if you have the time. Great vids, keep up the good work.

 @andybloomer: running a DB coil [IL] on my suppressor with 30% sag, 20% seems very high.

 @poah: sorry. My mistake. I meant 20mm 30% sag. Same as your set up

 @andybloomer: for someone your weight, you would need a 200-250 pound spring, that would really change up how your shock feels, also download the cane cree app and it has everything you need to get your shock dialed

 @SRAMIX29: not sure I'd agree mate. 300 lb spring with about 2 turns of preload gives me 30%. If I go lower spring I'd need to wind the preload way past the max 6 turns recommend to get the sag right, no?

 @VorsprungSuspension: Can you do an explanation of damper settings for different rear suspension kinematics? Like rising and falling rate of some VPP suspension curves, linear curves, steep progressive, high and low anti-squat designs, etc..

 @andybloomer: not sure why everyone is so focused on 30% sag. It's going to vary with settings/geo/preference...

 @nvranka: transition recommend 35%, didn't work for me but 30% does.

 @poah: same here mate, too many pedal strikes at 35

 @jdendy: that's on the list

 @andybloomer: Idk how you ride, but cane creek says for a 164lb rider you need a 225lb spring, from there, you just get lsc hsc lsr and hsr dialed in to how you want it to feel, turning the knobs multiple times is not a bad thing

 @SRAMIX29: I run a different weight spring to what CC spring calculator says.

 @SRAMIX29: I just visited the site, entered frame travel and total riding weight and it said 300 lbs for me.. I got some advice from the guys at TF tuned and they agreed. I was speaking with @poah earlier and agree that bold moves with the dials works well. I'm on:

2HSC although might go higher if the graphs show that doing so helps you get more out of the low speed
3HSR
only 1 LSC
17LSR.

Very little low speed rebound for me as I pedal well (ex roadie for over 30 years) so don't bob much anyway and wanted super sensitive small bump compliance. If I do feel the need to pedal for long distances uphill and want it more efficient I simply use the climb switch but otherwise prefer the suspension to work well and track the ground

All feels good now to me, these higher end shocks are awesome for adjustability

 @andybloomer: yeah, if you disagree with what the cc calculator says, that's perfectly fine, it all depends on riding styles, I run air suspension on my 180mm bike, and I weigh 150 but have my rear shocks set for a 200lb person simply because my style is just huck everything. I don't worry about being smooth as long as it's fast

 @SRAMIX29: that explains a lot. I like grip, so plush suspension. I get scared and out of my comfort zone if I'm in the air too long . But I'm hoping to improve

 @andybloomer: everyone is different when it comes to riding, I'm a racer, and my friends hate going dirt jumping with me because my style is fast not necessarily flowy. I just scrub everything and get to the bottom first. I don't really like big jumps, but enjoy stuff like hucking trail features such as a decent sized double with a roller afyer it, my brain says speed up and tripple it

 I'm hoping this is the case.

 That can help, but don't interpret that as meaning "more HSC is always the answer" or anything. When you want more LS support but increasing the LSC adjuster just increases harshness and not support, that's the time you want to be increasing HSC. If you already have a sufficient HSC threshold force, using the LSC adjuster is the thing to do, and increasing HSC may just make things harsher.

 @VorsprungSuspension: yeah, I think I just need to send you my shock for a service, dyno and possibly a revalve.

 I have the same shock, albeit the newer version without boost control. From what I can tell, it's supposed to stiffen the spring rate. I interpret that as it helps in the case of being between spring rates. Say you have a 400 and 450 lb spring, but you should be using is s 425 lb spring. If the 400 is installed, adding air pressure helps get you more in the 425 range. Not sure if this is correct, but it's how my brain sees it.

 The air pressure in the piggyback is purely for bottom-out. The spring rate of the shock is linear until the very end, with the air spring (set up at a relatively low pressure) providing a bottomless feel at the end of the stroke.

 There are two variants of the RC4 - the first generation with the 5/8" damper shaft and the Boost Valve, and the second generation with a 1/2" damper shaft and no boost valve.

First gen w/BV: the pressure affects the compression damping directly, in a position sensitive manner. That means it has the most effect at the end of the stroke. It also has some effect on the spring rate throughout the stroke; you'd run ~50lbs/in lighter on that shock than a shock with a very small shaft or very low gas charge pressure (eg CCDB).

2nd gen w/o BV: the pressure only affects the spring rate, and has the largest effect (which is still fairly small) at the end of the stroke. Long story but basically Fox got rid of the position sensitive aspect of the shock to make the damping entirely speed sensitive without having to introduce any parts they didn't already make.

 @VorsprungSuspension: Thanks Steve, Really appreciate all your amazing info.

 Correct - how much HSC you have wound on affects how the point at which your LSC support transitions into the proportionally softer HSC region.

 Sounds like what you want is simply higher pressure with the OTT preload wound further on. You'll still get the supple initial stroke, but with more support further in - that's the purpose of that adjuster, to let you separate average spring rate from the very beginning of the stroke's force curve somewhat so that you aren't creating harshness by running a firmer spring rate.

 I'm kind of wondering the same thing. I have a Diamond and have played with it quite a bit. I added some oil (for volume, like what spacers do) to the air spring to make it more progressive in the mid stroke or actually more at the end of the mid stroke as I felt it was bottoming too easily with OTT set to the recommended settings. This helped. But it still feels too soft mid stroke with OTT. More air pressure makes it way too firm and never bottoms out or uses the last 1" of travel. More LSC makes it too harsh. I've backed off the OTT and it rides like a traditional fork. I guess I want it more progressive towards the middle, might be in the OTT settings? It's a new fork, so I haven't found that sweet spot yet, but so far it's pretty amazing. Just need some tuning advice to get it perfect is all.

 @oldschool43: Try higher pressure (in 5% increments - note that's percent, not PSI) and winding the OTT to the plusher setting at the same time. You may also want to remove a bit of the oil you added so that you can reach full travel.

 @VorsprungSuspension: Thanks for the reply.
After thinking on it some more, i realized the compression knobs must affect the entire stroke similarly since it actually sits on a separate fork leg from the springs.
If i understood your video correctly, increasing HSC does not change the "spring rate" (i.e - slope) on high speed bumps. So, assuming i'm riding aggressive rocky trails, and most of my bumps are in high speed curve zone and in the middle of my travel (past the OTT), my ways to increase midstoke support are:
a) reduce spring volume (spacers, oil etc...)
b) add more air for a firmer ride


@oldschool43 - i actually try to leave the LSC alone. I mostly use it as "climb" switch to reduce some bobbing on climbs (although even when fully closed it's not nearly as "efficient" as other forks i've used). I share your feeling about midstroke support. Initially i used very little OTT, simply cuz i like my suspension springy and hop-friendly. But after adding more and more OTT, its hard to go back. the small bump sensitivity is addictive (and also adds about 200 grams to your fork, so you might as well use it

 @foxinsocks: HSC does not affect spring rate (unless you just meant gradient of the slope? In which case you are correct, but that's a confusing analogy!) - springs are a completely separate thing to dampers. It does increase the HSC force at any speed (above the threshold velocity) however, but primarily by offsetting that force.

From what you've described, I think reducing spring volume will do the opposite of what you are looking to do. It makes the fork ramp up harder - from what you have described though it sounds like you're after more support in the middle of the stroke. Adding air, increasing OTT and increasing volume will firm up the middle of the travel without affecting too much else.

The difficulty here however is being sure that what you're looking to improve actually is in the middle of the stroke, and that your perceptions on that are correct - it's pretty common to find that what a rider thought was happening a particular region of the travel was actually happening elsewhere. For example, a perception of a lack of mid stroke support (or sense of midstroke harshness) is sometimes actually happening 70-80% of the way through the travel, which is where ending stroke ramp up has a big effect, so you'll

 @VorsprungSuspension: I only added 25cc or so. Around 13mm of height, still has plenty of room fully compressed, maybe 50mm of space? It does get full travel with the OTT cranked up without it being noticed or a harsh top out. Sorry, when I backed OTT out, it didn't reach full travel. I'm a heavy guy (250lbs) and ride rough stuff. It just feels "soft" mid stroke to full compression. I've only ridden Fox and they feel like they have a bit more ramp up toward the last 40mm. It feels flat with the DVO, it's not packing up, it's the spring rate. I will try the pressure settings. I'm running the minimum, 140psi with 20% sag on a hard tail in attack mode, or standing on the pedals. It's close, was just thinking maybe it needs some volume.

 @foxinsocks: Yes, after riding a small bump sensitive fork like this one, I really like OTT. I could feel the difference in my wrists and hands after one ride. It turn up the LSC for climbing sometimes, but usually keep it open 1, or if there is a lot of pedaling 2. Just need to figure out the middle stroke.

 @oldschool43:
Straight up I'd say your best bet is to get in contact with Bryson Martin and ask for his advice. That's the brilliant thing about DVO is they are more than willing to give you top quality one to one advice on setting up your suspension.

But after riding Emeralds for over a year now, if the diamonds are anything like the emeralds that is, then I will admit they are a bitch to setup; mostly due to the vast amount of clicks on every setting. but that isn't necessarily a bad thing.

It's not a quick process. I went back and tuned the Emerald again the other month, and I ended up spending over 6 hours tuning it in, and I hadn't even got to the LSC by the end of the day! But once you get it dialled, it is so worth it.
Just find a nice section of trail that has a bit of everything (roots, rocks, drops, berms etc.) and play around with the fork, tuning one thing at a time. Get to know the fork and how everything works.

To help with tuning go from one extreme to the other. So, for example, turn the rebound fully clockwise and ride the section of track. Then ride the section of track but with the rebound fully anti-clockwise. After that you can begin to tune in 2 clicks or so at a time and find the sweet spot.

DVO have a YouTube channel, with vids talking you through setting up your diamond, emerald etc. They are very helpful.

 @Jack-McLovin: i definitely agree and so far DVO have been very responsive. Just enjoying a nice tech discussion here with the vorsprung guys.

The versatility of the tuning on this fork is has its pros and cons. It's very not fool proof, and requires experienced riders to get the max out of it (as opposed to a "CTD" approach which any idiot can figure out).
I actually do the same approach as you described - going to the extremes to get a good sense of the affect and range. Still, with so many factors affecting compression (HSC, LSC, OTT, air pressure) its hard to place a finger on it. Not to mention that a certain setup might feel awesome in fast chatter trails and bad on slow technical stuff. It's difficult to find "golden rules" with so much dials.

 @Jack-McLovin: (Nice profile name!) I've only had the Diamond about 3 months, but have 20 rides or so on it. I know how most things work when it comes to forks. I've added volume to my air (and coil) forks for 20+ years, can feel when I need an oil change based on performance, etc, but this fork is a whole new adventure.

I set the rebound first on every fork so I went with the base tune and set up the rebound first. So my first ride on it, I rode a short, rocky, rooted, 1 mile loop with some fast descents and stopped at the truck to make adjustments each lap, adding and subtracting. I had it setup to my liking, except for the mid stroke thing. I thought it needed volume, so I pulled the air valve out and inserted a syringe with fluid. Did a lap, added more, and so on. It changed it some, it still wasn't perfect, but plenty rideable. Then I went to a trail with jumps, that's where the mid stroke issue reared it's ugly head. I turned up the HSC a bit and the LSC and I was still bottoming the fork on the face of the jumps hard. I could feel the compression working, but that was the only thing working. Once it hit so hard the tire collapsed (35psi) and it sent me over for a visit with a tree. With the jumping setup, set to 20% sag and on a regular trail, way too firm. Started over on the settings and haven't strayed too much since.

I actually just got around to re-installing my 15' Fox 32 Factory Fit 4 on my other bike this weekend, after 3 months. I had it set it up rigid and kind of liked the challenge and after the rebuild, I didn't want to get my hands dirty.. Okay, was just being lazy.. So I have only ridden the DVO for 3 months. Anyway with the Fox, even in descend mode, or technically no compression damping, I still don't bottom harshly or have any volume added to it hitting the same jumps. I didn't even use full travel (had 10mm or so unused), also set to 20% sag but with 30psi in the tires. Currently, the Fox blows the DVO out of the water as far as the spring curve goes. I want to figure out that spring curve. Maybe I just need more oil (volume) in it..

 For really big hits, HSC and spring rate are what matter. LSC isn't really relevant there. Rebound requirements are only really related to spring rate, so you shouldn't have to worry too much about that between different riding contexts.

 You are somewhat correct with the unweighted wheel being able to move faster than the sprung mass of the bike when the wheel is on the ground. However, the spring RATE is relatively consistent but the spring FORCE depends where you are in the travel. Where LSC becomes HSC in terms of the damping curve is dependent on damper configuration and setup, so in some situations the HSC will be affecting the movement of the bike/rider and in some cases those movements will be occurring within the LSC realm.

 @VorsprungSuspension: I was curious about LSR and HSR, not LSC and HSC. Is that what you were referring to?

 Yes and yes. If you have two compression circuits in parallel, one preloaded and one linear, adjusting the preload on the preloaded one also affects the overall gradient. The CCDB and X2 dampers are an example of this (in compression).

 @VorsprungSuspension: Does this apply to the CC inline as well?
Excellent work and huge thanks on the video, I love knowing more about how my kit works and this feels like having a personal tutor to teach me!

EDIT: I've just watched the DSC video below- so for CC and X2 dampers, the combination of the shim stack and adjustable rod valve/poppet allows you to alter the HSC damping curve? As I understand, the shim stack is used to control the compression curve, and the rod/poppet is used to control the 'transition threshold' from LSC to HSC?

 @VorsprungSuspension: does that mean with the X2 that the point at which LSC transitions to HSC is not adjustable?

 @spicer: basically yes. When you increase preload on the poppet valve, it essentially forces more oil through the other compression circuit at any speed high enough to be opening the valve, instead of allowing as much oil to flow through the poppet. Because the other (shimmed) compression circuit has a linear force vs oil flow rate characteristic, any increase in the poppet's preload then results in a steeper force gradient and a higher HSC offset at the same time.

 @Creg: no, it adjusts both the HSC threshold and the HSC gradient simultaneously. Notably this does not apply to rebound on any of those shocks except the DB coil.

 Rock shox vivid and vivid air have beggining and ending-stroke rebound adjusters that let you achieve that

 There are shocks out there that do this. In certain circumstances I agree with you.

@nehuen93 the beginning and ending stroke (LS and HS) rebound adjusters (which we'll get into more next week) don't actually let you create quite the progressive curve @Kramz was describing.

 @VorsprungSuspension: Isn't this what push does using - a modified shim stack to control rebound velocity depending on distance into stroke?

 @nicolai12: All shimmed valves are speed sensitive, but all rebound velocities are constrained by distance into stroke. For example, you can't reach the same peak rebound velocities at 25% travel as you can at 80% travel because the spring force built up at 80% travel is much higher. So what you've said is applicable to any variable aperture rebound valve.

 Check out last week's video on damping vs springs

 Correct, the LSC circuit is always somewhat active. However, in some cases the flow area of the LSC circuit is so minimal compared to that of the HS circuit, that once the HS circuit opens, the LSC counts for a tiny percentage of the restriction. It varies a lot from fork to fork, shock to shock. In some cases the HSC circuit only increases the flow area by a max of 50%, in other cases it's more like 5000%. The variation is huge.

There are cases where the HSC adjuster does affect the HS gradient too - any time there are two variable aperture circuits in parallel, this can happen. For example, any of the CCDB series compression circuits.

 The specifics of that depend on the damper in question. The Float X for example does restrict both LSC and HSC in the Climb mode, giving a very firm feel, as does the Float DPS. Having a climb mode that firm makes it pretty much exclusively for smooth climbs, or very low speed stuff, because neither of those shocks want to move much at all when using the climb mode on rougher technical climbs. Most other shocks work only on the LS circuit, which does tie the platform firmness to your HSC threshold. In most actual off-road situations this is fine, though some people do want it firmer for smoother climbs.

 Did a little bit of a double take when i saw that

 That DSC video has some great animations that really illustrate the flow paths well, thanks for the link. The Rod Valve System though is just another name for a poppet valve system that is pretty much identical to what's inside the Cane Creek shocks.

 LSR would be what you're looking at predominantly (rather than LSC), but maxing that out on any damper I can think of might not really be ideal...

 @VorsprungSuspension:
HSR fast and LSR slow and keep LSC/HSC normal?

 @trauty: If that's what you like, sure. Really depends on the shock too, no two are identical.

 Easier way to do that would just be to change the spring stiffness. The effect, up to choke velocities, is the same.

 We'll get more into practical setup concepts of that and the HSC/LSC next week.

 They do exist actually, but the more variables you have, the more things you can get wrong.

 Australians call them prawns

 @VorsprungSuspension: all kidding aside, thanks so much for these vids, been watching all of them ... comes at a good time as I've got a Float X2 on my Nomad now so lots of fun things to think about. The part for me which drove it home was the idea that lowering your high speed can reduce the range over which low is effective. I always looked as at them as 2 circuits independant, but didn't think about the relationship part. Cool!

 To make it wet?

 @jarradlawrence: I believe the technical term is "damp"