setting up rebound?

[urastus]

watching videos trying to sus out rebound settings. I understand the theory, but until today I couldn't tell you one way or the other, by feel, if one setting was good or bad Found this simple video, and just ran through it on my bike and my partner with her bike - awesome! I could feel the change and see it. The phone camera has slomo mode, which is really handy for this. This is just for the rear

 

[Gary]

I posted links to Andre's Youtube channel and his suspension fundamentals playlist in the suspension set-up guides "sticky" topic at the top of this (General Emtb) forum.
it's been there for 2 years

 

[urastus]

Doh! I actually had a look there, saw a couple of familiar videos I was familiar and frustrated with. Didn't see the one that mattered. I don't know how to delete this thread now, so I'll leave it.

 

[Zimmerframe]

In case anyone stumbles here ... and wants to go there ...

Suspension set-up guides and info

@Rob Hancill There are a lot of threads on the forum asking questions about suspension set-up. I think it would be good to sticky a guide to suspension set-up for all users to easily find. @steve_sordy just posted an excellent and fairly thorough PDF guide to suspension set up in the commencal...

www.emtbforums.com

IF you want the thread deleted .. just put .. Dear Mod .. please delete this thread - it should automatically delete it then.. I do it all the time on other peoples threads which don't' have any humour in them ...

 

[urastus]

In case anyone stumbles here ... and wants to go there ...

Suspension set-up guides and info

@Rob Hancill There are a lot of threads on the forum asking questions about suspension set-up. I think it would be good to sticky a guide to suspension set-up for all users to easily find. @steve_sordy just posted an excellent and fairly thorough PDF guide to suspension set up in the commencal...

www.emtbforums.com

IF you want the thread deleted .. just put .. Dear Mod .. please delete this thread - it should automatically delete it then.. I do it all the time on other peoples threads which don't' have any humour in them ...

In the first post? Or in the title of the thread? Or in the title of someone else's thread?

 

[Mteam]

The fox setup guides usually get you to pretty much the correct damping settings just by looking at the table of damping settings for any given air pressure. Doesnt help if you dont have a fox shock, but if you do I usually find them spot on.

for example : the 2020 fox float x2 damping settings part way down the page SHOCK- 2020 FLOAT X2 | Bike Help Center | FOX

 

[urastus]

The fox setup guides usually get you to pretty much the correct damping settings just by looking at the table of damping settings for any given air pressure. Doesnt help if you dont have a fox shock, but if you do I usually find them spot on.

for example : the 2020 fox float x2 damping settings part way down the page SHOCK- 2020 FLOAT X2 | Bike Help Center | FOX

I've never had any luck with any of them - not even close . Not even for sag.

 

[Mteam]

I've never had any luck with any of them - not even close . Not even for sag.

I was going to say (but decided against it for some reason, but you'll note I didn't recommend their weight and air pressure charts, just their damping chart ) to ignore the setup guides for sag, and just set sag using whatever method works for you, but once you have your air pressure set, reading off the damping chart for the air pressure you're using seems to work for me.

 

[urastus]

I was going to say (but decided against it for some reason, but you'll note I didn't recommend their weight and air pressure charts, just their damping chart ) to ignore the setup guides for sag, and just set sag using whatever method works for you, but once you have your air pressure set, reading off the damping chart for the air pressure you're using seems to work for me.

if that works, that's a great idea! I'll try that too. It's nice to see that it is working the way it is supposed to though; that's what I like about the curb technique. What you suggest might be a good thing for the fork - setting that up seems subjective otherwise.

 

[Mikerb]

I agree. It's difficult to see how any set of recommended settings can work when the shock can be installed on a range of bikes with different kinetics which may be more or less progressive/linear. I suspect that also applies to compression. Return speed ( rebound) should however have a consistent relationship with air pressure regardless.

 

[urastus]

I agree. It's difficult to see how any set of recommended settings can work when the shock can be installed on a range of bikes with different kinetics which may be more or less progressive/linear. I suspect that also applies to compression. Return speed ( rebound) should however have a consistent relationship with air pressure regardless.

I just tried the online rockshox setup guide for my fork. I'm using 55psi, that probably bottoms out once every 4 or 5 rides, which seems ideal. If I enter my weight as 45 kg (I actually weigh 80kg) and select emtb, it comes back with 55psi and -13 clicks rebound. That is what I have it on now. I was just going for a pretty fast fork - beginner's luck. Thanks again mteam; I'll use that method for all forks (I have a couple more bikes, and my partner's).

 

[Mikerb]

keep in mind that the starting point for both compression and rebound is determined by the factory tune and if you only have one rebound setting it is Low Speed Rebound only really affecting small bump and undulation compliance. I find it is invariably best at around 30% from fast assuming the fork has a medium factory tune..............close to open/full fast if the factory tune is firm.

 

[Gary]

No mike. If your shock only has ONE rebound adjustment it controls BOTH high and low speed adjustment.
Otherwise your shock would top out like fuck and spring back uncontrolled on high speed hits.

 

[Mikerb]

OK...does that also apply to Compression? I thought the factory tune applied for high speed hits??

 

[urastus]

keep in mind that the starting point for both compression and rebound is determined by the factory tune and if you only have one rebound setting it is Low Speed Rebound only really affecting small bump and undulation compliance. I find it is invariably best at around 30% from fast assuming the fork has a medium factory tune..............close to open/full fast if the factory tune is firm.

I think you might mean compression damping? Some high end suspension have high speed and low speed compression. Mine only has low speed. I use it both ends if I'm playing on jumps or drops, or only the rear if I'm climbing or pedalling on the flat; otherwise it's wide open. I'm guessing low speed compression would affect bigger, slower stuff - that's usually what stops my suspension from bottoming out when I land flat or case ; those are generally high speed hits but it still makes a difference.

 

[Mikerb]

I have a high and low speed compression on one of my bikes ( fork) and both high and low compression and damping on the other so different set up. With low and high speed settings the low speed only affects the speed of compression/return on small bumps and undulations. Gary corrected me re the effect of compression/rebound settings if there is only one setting.

 

[urastus]

I have a high and low speed compression on one of my bikes ( fork) and both high and low compression and damping on the other so different set up. With low and high speed settings the low speed only affects the speed of compression/return on small bumps and undulations. Gary corrected me re the effect of compression/rebound settings if there is only one setting.

I think you might still misunderstand it, or I've misunderstood you Compression damping slows down the compression of the suspension; it doesn't affect return speed. I think that's right? Rebound damping affects the speed of your suspension returning to extended? Gary was talking to you about rebound damping only. If you consider the names; compression (contraction), rebound (extension / returning). Just going by the name, I would think low speed compression works on larger, more rounded (basically slower) hits, high speed would work on sharper (faster) hits big or small? Lots of small bumps together are probably high speed? Any small bump might be high speed because of the speed you go over it would make it a fast hit? Although you could go over it slowly, too, which would make it a slow hit? I'm guessing that most of us run over small bumps at speed.

I just had a quick look at this article from Gary's suspension sticky; article linked by Steve Sordy Suspension Tech: How does high speed compression damping differ from low speed? - Bikerumor. They say that jumps and drops are high speed (that makes sense); despite this, I've found that by applying low speed compression damping (I don't have high speed) it does lessen the amount of suspension I use, quite a lot. I've measured with and without when playing on jumps and drops etc.

Update: rather than read my gobbledy gook, I found another good easy to understand page on compression damping (low and high speed) and rebound How Mountain Bike Suspension Works | evo

 

[Mteam]

When they say high speed and low speed they are referring to the speed the shaft of the damper moves at, not the speed the bike is going. Low speed compression events are typically caused by weight shifts of the bike, eg rider moving their body around, or compression from pedalling and braking forces, or maybe landing from a jump onto a nice smooth transition. The key is that the movement of the shaft is over a longer period of time ie is slower.

High speed compression events are typically from the trail eg square edged bumps in the trail, badly cased landings or landing to flat.ie fast movements of the shaft

It depends on the damper design how much adjusting the low speed comp damping also alters the high speed(and vice versa) , some designs isolate the two adjustments from each other better than others. It's a complicated thing.

 

[Gary]

OK...does that also apply to Compression? I thought the factory tune applied for high speed hits??

Mate. your damper is simply an adjustable port and (fixed) shim stack that oil flows through. the more you wind on the damping adjuster the harder it becomes for that oil to pass through (Very simplified explanation). This is what slows the rebound/compression speed of the shaft.
Unless your shock has a bypass circuit the oil has to pass through those same shims/ports whether the shaft is moving quickly or slowly.
So what do you think?

 

[Waynemarlow]

Don't forget to mention the words "suspension packing" and the rule of thumb that you should be using all of the travel of the shock at least once on every ride, or you have the shock setup too hard.

 

[Mikerb]

Mate. your damper is simply an adjustable port and (fixed) shim stack that oil flows through. the more you wind on the damping adjuster the harder it becomes for that oil to pass through (Very simplified explanation). This is what slows the rebound/compression speed of the shaft.
Unless your shock has a bypass circuit the oil has to pass through those same shims/ports whether the shaft is moving quickly or slowly.
So what do you think?

from the SRAM/Rockshox Fork Tuning Manual.........."
LSC damping adjustments have less effect during high speed compression
stroke scenarios. Drops and large bump impacts can exceed the LSC
damper's effective range of control and will cause the suspension fork to
compress suddenly and quickly, regardless of the LSC damper setting"

Dampers like the Rockshox charger only have one compression setting....Low speed compression.

 

[Gary]

Oh FFS! Make it STOP!

 

[urastus]

from the SRAM/Rockshox Fork Tuning Manual.........."
LSC damping adjustments have less effect during high speed compression
stroke scenarios. Drops and large bump impacts can exceed the LSC
damper's effective range of control and will cause the suspension fork to
compress suddenly and quickly, regardless of the LSC damper setting"

Dampers like the Rockshox charger only have one compression setting....Low speed compression.

Gary did mention "Unless your shock has a bypass circuit the oil has to pass through those same shims/ports whether the shaft is moving quickly or slowly. "

 

[Norcalsl]

It's not rocket science. The point is to eliminate a pogo stick effect.

 

[Mikerb]

Gary did mention "Unless your shock has a bypass circuit the oil has to pass through those same shims/ports whether the shaft is moving quickly or slowly. "

yes, the oil circuit and shims assuming no external controls determine the speed of compression. The shims provide a progressive response meaning the response will be fastest at the beginning of the stroke. Hence most forks at least provide a low speed compression external setting to close off some of the ports. This makes the speed of response of the stroke slower over small bumps, undulating ground and the slower type of stroke when riding a berm. But as the extract from the Rockshox tuning guide explains, the means of adding slow speed compression cannot withstand the harder/longer stroke hits. So with harder hits the speed of compression is determined mostly by the factory shim stack setting. I have never seen an explanation however of how a single rebound external setting affects the speed of the return stroke both for slower compressions and harder hits. When the fork has both high and low speed compression........and if it also has both low and high speed rebound, the internals obviously get a bit more complex!! Always happy to learn more...or differently!!

 

[Gary]

FFS