# HSR vs LSR on Jumps



## scepticshock (Jun 6, 2005)

Which matters more on taming the buck on jumps? High or low speed rebound, or a combo of both? I have an X2 so the variables are daunting.

I'm having a hard time finding a balance between running it fast enough to prevent pack up on rocky trails, and keeping it sailing nice and balanced in the air. I'm not a very good jumper, and nothing kills confidence more then feeling that back end come up too high. Thanks!


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## Deerhill (Dec 21, 2009)

Sounds like front/rear spring rates don't quite match, I'd start there...never used x2 though is that air spring?


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## kenbentit (Jan 2, 2003)

Think of the 2 types of impacts as a sine wave (low speed) Vs a square or triangular wave (high speed). The "speed" in those settings is referring to how fast the impact affects the bike which is both a factor of the shape of the obstacle as well as the speed that you're hitting it. On the takeoff of a jump you're going to be using more of the LSR/LSC, the HSR/HSC come into play more on square edge impacts and drops. Have you looked at the Fox chart for the recommended settings for the shock? I've found them to be pretty close to where I want to be, only made a couple of minor adjustments for personal preference. 
And as J mentioned, having the front and rear suspension balanced is very important. I find myself experimenting with front suspension setup more than rear...


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## scepticshock (Jun 6, 2005)

Thanks guys. Yes I am using the recommended ranges, though I tend to want to run the LSC slower for jumps. I haven't really played with HSR much, but it sounds as if it shouldn't effect take off much as rocks and sharp impacts.

J-yes the X2 is an air spring.


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## Christopher Robin (Dec 1, 2004)

The HSC shouldn't be affecting your jumps as that adjustment is supposed to be independent of the LSC. If your backend is bucking you up, could be you're not centered enough during takeoff, or the LSR is too fast or both? 

For shocks like that, write down what Fox recommends and keep track of what adjustment you're changing. Only mess with one thing at a time.


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## Miker J (Nov 4, 2003)

scepticshock said:


> Which matters more on taming the buck on jumps? High or low speed rebound, or a combo of both? I have an X2 so the variables are daunting.
> 
> I'm having a hard time finding a balance between running it fast enough to prevent pack up on rocky trails, and keeping it sailing nice and balanced in the air. I'm not a very good jumper, and nothing kills confidence more then feeling that back end come up too high. Thanks!


Bucking...

It's a HSR issue.

Hit a high speed jump with a steep face and you are going to sink way into your travel, especially if you load up on the bike's suspension.

When the shock rebounds from deep in its travel most likely you'll be dealing with accelerated shaft speeds, regardless how fast the bike itself is going downhill. There is a lot of psi pushing back when the shock gets loaded on a jump's face.

So, we'd be dealing with, at least in part, HSR.

For example, look at Rock Shox Vivid coil. That's what came stock on my DH rig. They don't name their rebound settings LSR/HSR. They call in beginning stroke and ending stroke rebound. Their beginning stroke equates to LSR, and their ending stroke equates to HSR.

Rock Shox goes on to specifically say....

"Ending Stroke Rebound - designed to control the speed at which the shock extends to its full travel position after a large compression. Ending Stroke Rebound can be tuned to allow the suspension to recover quickly from a large bump or reduce "bucking" from a large
bump."

https://sram-cdn-pull-zone-gsdesign...efault/files/techdocs/vivid_pocketguid_en.pdf

This is not to say that LSR does not play a part, but I think it's more of a HSR issue. Too much of LSR damping may cause packing. Too little and body weight shifts make the bike move too much, and also the suspension may feel too chattery.

Also, you can get a bucking sensation if your fork is under sprung or it's rebound damping is too slow.

And BTW, the X2 is a awesome shock. Put one on my AM rig a few days ago. Completely blown away. As an aside, I got a super deal on an X2 from my bike's maker as I repeatedly killed the Float X. Their tech's gave me their recommended set up. The rebound felt pretty slow, and I'm usually running more rebound than that average joe. But, on the trail, the shock feels incredible. On the downs, feels like a DH shock. I do run more LSC than recommended, but I don't like the bike to feel soft at slow speeds. The shock totally opens up once the speed picks up... perfect !

Kenb...

As an aside, not sure if or how you are affiliated with Pivot, but the X2 went on my Mach 6. I'm a skeptic, and rarely expect too much out of any new product, but I was blown away by what the X2 did for the M6. And that's against a PUSH'd Float X.


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## scepticshock (Jun 6, 2005)

Miker J said:


> Bucking...
> 
> It's a HSR issue.
> 
> ...


Thanks for your input! May I ask what your PSI and rebound settings are for your X2 on your M6?
I'm on an HD3 so they are fairly close. The settings per Fox's guide seem a little on the fast side.


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## kenbentit (Jan 2, 2003)

Yeah, I work at Pivot. I'm a HUGE fan of the X2 (also on my M6), such an easy shock to setup and tons of adjustability. Totally agree with the suggestions on jump setup, it's hard to dial in just one setting for that as you're going to be crossing into the range of both High & Low speed settings at different points. I prefer to run my suspension with minimal rebound damping but a firmer compression setup so it has plenty in reserve when I get into the rougher sections.


Miker J said:


> Bucking...
> 
> It's a HSR issue.
> 
> ...


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## kenbentit (Jan 2, 2003)

Here's my current setup for the X2 on my Mach6 (rider weight is approx 185 lbs)

Air: 175 psi
HSR: 14
LSR: 17
HSC: 19
LSC: 18 
(all these are from fully CLOSED)


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## scepticshock (Jun 6, 2005)

kenbentit said:


> Here's my current setup for the X2 on my Mach6 (rider weight is approx 185 lbs)
> 
> Air: 175 psi
> HSR: 14
> ...


Cool! Thanks!


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## Miker J (Nov 4, 2003)

kenbentit said:


> Yeah, I work at Pivot. I'm a HUGE fan of the X2 (also on my M6), such an easy shock to setup and tons of adjustability. Totally agree with the suggestions on jump setup, it's hard to dial in just one setting for that as you're going to be crossing into the range of both High & Low speed settings at different points. I prefer to run my suspension with minimal rebound damping but a firmer compression setup so it has plenty in reserve when I get into the rougher sections.


Cool. Small world. Would like to give you guys at Pivot a HUGE thanks. Your customer service is great. The M6 continues to amaze me and I think this will be its 4th season for me. Yesterday I saw you guys even took the time to paste the red-line sag indicator on my X2. Thanks again.

To the OP, settings....

Pretty close to Kenb's and I'm about the same weight. Can't recall the exact numbers right now, but I do know I'm running a hair more on the spring at 180-185 psi. The attack position puts me a little short on the correct sag, but seated I'm good. I've got super long levers and when seated on the steep climbs I sink into the my sag quite a bit.

I prefer a stiffer setup too. Suspension set up to feel nice in the parking lot often feels soft out on the trail.


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## Deerhill (Dec 21, 2009)

*Weight balance*



scepticshock said:


> I'm on an HD3 so they are fairly close. The settings per Fox's guide seem a little on the fast side.


What fork are you riding for DH/chunk, iirc that linkage is based @545mm axle to crown? Any adj/setup notes and how they're affecting the ride after runs...is it that you keep closing free bleed and it's just not helping?

I'm thinking that x2 is a newer fox air (twin tube design), so more than likely some adjustments up front would help real in the HD3 buck...as in +20mm a-c to start if you have the capability

Nice frame btw


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## scepticshock (Jun 6, 2005)

J: said:


> What fork are you riding for DH/chunk, iirc that linkage is based @545mm axle to crown? Any adj/setup notes and how they're affecting the ride after runs...is it that you keep closing free bleed and it's just not helping?
> 
> I'm thinking that x2 is a newer fox air (twin tube design), so more than likely some adjustments up front would help real in the HD3 buck...as in +20mm a-c to start if you have the capability
> 
> Nice frame btw


Thanks guys. Is that your ready to ride weights? Also curious about how many spacers you are using in there.

I have a Fox 36 160mm that just received the Push Factory tune, and I am pretty much within a click of their setting with 70 PSI. My riding weight is 183. The fork feels great.

I also just had my pivots redone also, so started re-evaluting my settings. I had noticed I was experiencing harshness to the rear and and that my LSC was pretty slow. Speeding it helped, but is now affecting my jumps. BTW in the X2 I run 160psi and have in 1 spacer in addition to the red limiter.


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## Deerhill (Dec 21, 2009)

*Either rear oversprung somehow or...*



kenbentit said:


> Here's my current setup for the X2 on my Mach6 (rider weight is approx 185 lbs)
> 
> Air: 175 psi
> HSR: 14
> ...


This is a big clue in that x2 circuit, at least for me...

OP, 70psi in that 36 sounds quite under sprung (for freshly serviced stock rc2 and no air spacers). Big weight difference though, Kenbentit is way closer to your rtr weight

*Edit- looks like Miker J is same rtr weight too*


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## NWS (Jun 30, 2010)

FWIW, every time I've seen a video of some getting "bucked" it has looked to me like they really just had their weight too far forward at takeoff. 

That said, I agree with kenbentit that jumping is more likely to be using the low-speed circuits than the high-speed circuits.


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## scepticshock (Jun 6, 2005)

J: said:


> This is a big clue in that x2 circuit, at least for me...
> 
> OP, 70psi in that 36 sounds quite under sprung (for freshly serviced stock rc2 and no air spacers). Big weight difference though, Kenbentit is way closer to your rtr weight


I forgot to say I use 2 blue spacers in the fork.

I have heard it said by a few folks, and even Darren from Push, that bucking can be caused by not running enough LSC. Is this because you are not going as deep into the shocks stroke and engaging the HSR?


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## Deerhill (Dec 21, 2009)

scepticshock said:


> I forgot to say I use 2 blue spacers in the fork.
> 
> I have heard it said by a few folks, and even Darren from Push, that bucking can be caused by not running enough LSC. Is this because you are not going as deep into the shocks stroke and engaging the HSR?


I've noticed it too, the free bleed is definitely part of it. In the 36 specifically, adding air volume spacers basically takes spring rate away from the top of the stroke (so for same psi it will absolutely affect f/r weight balance and dive much more compared to no spacers). Adding a volume spacer also makes LSC much less effective at the top of the stroke (because there's less spring rate/support), that spring rate is effectively moved/added to the end of stroke spring rate.

*Assuming this bucking is something new to your suspension retune correct?


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## Miker J (Nov 4, 2003)

scepticshock said:


> I forgot to say I use 2 blue spacers in the fork.
> 
> I have heard it said by a few folks, and even Darren from Push, that bucking can be caused by not running enough LSC. Is this because you are not going as deep into the shocks stroke and engaging the HSR?


Yeah, what u said, makes a lot of sense.

Funny thing is, bucking has way more to do with body position on the bike. Head out to a pump track on a rigid bike.


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## scepticshock (Jun 6, 2005)

Thanks guys. I think Push takes the bike frame into account. I asked for more of an aggressive trail tune, not a big hit tune.

I wish we had a pump track around here. I hear they are working on it but likely its years out. I'm sure body position is a factor. Wen you feel less confident you may not be as centered as you should be.


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## <Steven> (Nov 14, 2007)

I just went through this myself with the same shock (X2). 

It didn't buck if I hit jumps going slow (warm up DH runs) but when riding the same jumps at a decent speed it would buck hard. So I didn't touch my HSR and LSR at all (was already at the low end of the bracket for HSR and was at the high end of the bracket for LSR) but increased both my LSC and HSC... fixed! Now I can hit lippy jumps at speed and take off perfectly balanced because I'm not blowing through travel on the take off... the bike remains supported instead. 

It's also super important to make sure your fork isn't under sprung as well... so aim to make it balanced with the rear once you turn up the LSC and HSC (I turned up the LSC on my Boxxer as well until I got that balance). Change 1 setting at a time and go from significant open to closed changes (bracket it) to get a feel for what each setting does. You might even need to increase fork air spring pressure or go to a firmer spring in the fork.


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## Gemini2k05 (Apr 19, 2005)

NWS said:


> FWIW, every time I've seen a video of some getting "bucked" it has looked to me like they really just had their weight too far forward at takeoff.


Usually it's the opposite. If you have your weigh biased forward you are able to push the bike down and lean back to compensate from "bucking". You see beginners make this mistake all the time. They lean way back on jumps to "play it safe" and the bike just ends up rotating forward and they go over the bars. If you watch good jumpers or Pro DJers they are basically standing straight up on steeper/bigger jumps.

But yeah, on a MTB any "bucking" is almost purely from poor riding, not suspension setup, unless your suspension setup is wayyyyyyyyyy off. On moto this is not the case.


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## scepticshock (Jun 6, 2005)

For sure its always best to be in a lightly forward posture. If only for getting you in a more aggressive attack mindset, and not a fearful retreat. But I think it also helps to keep you neutral and centered.
^ true about the pros pretty much standing up with the bars in pretty close. But when I make suspension changes I kind of have to relearn my technique again. I just firmed my shock up as per a few set up comments here, so I now have a true 17mm, and a bit more in my fork too, and it feels quit different.


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