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SCARY

Not long enough
I'm in no way fast,but I'm wondering if I'm missing something by running my suspension the way I do.

I run forks stiffer than anyone I know.Their not stupid stiff,and I've softened them up after I started running higher psi in my tires for better rolling resistance and getting no more flats.

My rear is pretty standard,I think.It's pretty soft in the beginning and my preference is for it to ramp up quickly.

I really hate diving in my fork,the Dorado is awesome for dialing that out.

Lately I've noticed that Gwinn seems to have really softened up on his fork.Gee seems to run his stuff really soft all the time.And Hill might have lightened up,maybe not.Or is it that these guys tracks are so fast most of the time,that's what they need to do,where I'm trying to not get hung up in imbedded rocks?

Am I reading this wrong or do I need to relearn how to ride?We got a lot of rocks and Bouldery stuff out here,but it's generally not that way everywhere else.The last really good feeling race I had was probably Schwietzer,a long time ago.
I dunno, softer feels awkward ,but maybe I've gone to far and am screwing myself outta speed.Id like to hear some informed school of thought,but all the kids at Pinkbike have gone night night.
 

Rhubarb

Monkey
Jan 11, 2009
384
174
I am in no way fast and quite lazy when it comes to fine tuning my suspension. I find it easier to get my fork dialled in but struggle more with my shock. Together with not getting around to trying small adjustments I end up with a shock that feels good but could probably be better.
I also find that firmer works better. When I got into bigger bikes I thought the whole point was to run them soft but I hated it and when I firmed things up I found out what it meant to get hung up.
My newest discovery is HSC. I always thought it was really just for BO control. I noticed I was getting hung up on certain big rocks at speed, resulting in a sound like my tire was flattening and the rim was striking the rock. I remembered reading a few days prior that HSC also has to do with shaft speed not just for BO. Since this was a high speed hit I added HSC and instant improvement. Now I realise I could still make some LSC, HSC and rebound adjustments cause while I know I am close 1 -2 clicks from where I am at could take the shock from good to great. The trick is knowing there is a section that you know well enough, feel confident enough that you will feel the difference and feel relaxed enough not to crash while you try and feel the shock out. I think I have found a couple of places and I am just at the point of trying to get my Jedi in that sweet spot so I am really looking forward gettuing my shock back from service and seeing what I can come up with.
I have always wondered what someone who knew what they doing took my bike for a ride and gave me feedback. I ride solo so not likely to happen.
I would also really like to hear other opinions.
 

buckoW

Turbo Monkey
Mar 1, 2007
2,336
1,712
Champery, Switzerland
Gwin rides some of the firmest suspension out of all the riders. He just rides so fast it looks like it is soft. Gee also rides with a lot of compression.
 
Aug 4, 2008
328
4
Indeed - Imagine your average pro taking average amateur bike (with soft suspension set for 75kg Joe Average) and then hit your average WC track at speeds 30% higher than you (we) do. Now calculate the forces (they should be much higher than 30%) and now imagine those forces being translated into damping.

I weigh 100 kilos. I had my suspension tuned by TFTuned and they cranked the compression up madly. Everybody that tries my bike calls me and its setting insane, because everybody is used to undersprung and underdampened bikes. The only thing I know is that the bike performs awesomely now.
 
I'm far from a pro or from going fast, but I also like to have my suspension cranked up.

I feel that, past certain speeds (when you start to "float" over stuff), too much sag doesn't really make the wheel follow the trail any better; it just drains your speed and pedaling efforts. Also, on steep sections, makes diving easier.

When I try my friends' bikes and I brake, I eat half the travel (ok, being 5-10kg heavier also helps). Maybe it's just me, but I don't understand how that is practical. No wonder people have so many bottoming out issues then.
 
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babw

Chimp
May 26, 2008
5
0
Gwin rides some of the firmest suspension out of all the riders. He just rides so fast it looks like it is soft. Gee also rides with a lot of compression.
I had a ride on Gee's bike awhile ago (the Athertons used to live local to me) and couldn't believe how much compression dampening he had! The rebound was pretty fast as well.

His reasoning was that the top guys put so much more input/work into the bikes during cornering etc they'd be bottoming the bikes on every other turn if they rode with the compression dampening of the casual user. They're also much less prone to fatigue so can afford to do it.
 

dw

Wiffle Ball ninja
Sep 10, 2001
2,943
0
MV
As a general rule, the faster you go, the more energy your suspension needs to absorb and dissipate. That means that as you go faster, you need to run additional spring support, and becuase the rebound damper's job is to dissipate the energy stored in the spring, you will need more rebound to go with the higher spring force. Additionally, sometimes faster guys will need to run slightly more HSC, but not a drastic amount. LSC will not change and all things being equal (like certain suspension designs NEED to run more LSC to accelerate acceptably), is largely tuned based on rider weight and more importantly the style of the rider (finesse -vs- gorilla).

Stiffer suspension is directly averse to reducing variations in tire load. The less variation in tire load, the more traction the tire is capable of. This goes for all tires, from mountain bikes to the ones on the space shuttle. Therefore, your goal as a suspension tuner should be to set up your suspension to use as little spring and damping as you need to handle the bumps and weight transfer requirements of the course, rider style, and bike. Anything more and you are giving up traction. That doesn't mean that you should be setting your bike up like a marshmallow, you just don't want to set it up with an absurdly greater stiffness than necessary.

There is nothing "cool" about running your stuff too stiff. It doesn't make you more of a man, it just makes you slower.

Hope this helps,

Dave

Can't wait to see the "tags" on this one!:D

edit: quick clarification to LSC, wouldn't want to cause an international incident by not being totally clear..
 
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ianjenn

Turbo Monkey
Sep 12, 2006
2,869
613
SLO
w

Stiffer suspension is directly averse to reducing variations in tire load. The less variation in tire load, the more traction the tire is capable of. This goes for all tires, from mountain bikes to the ones on the space shuttle. Therefore, your goal as a suspension tuner should be to set up your suspension to use as little spring and damping as you need to handle the bumps and weight transfer requirements of the course, rider style, and bike. Anything more and you are giving up traction. That doesn't mean that you should be setting your bike up like a marshmallow, you just don't want to set it up with an absurdly greater stiffness than necessary.

There is nothing "cool" about running your stuff too stiff. It doesn't make you more of a man, it just makes you slower.

Hope this helps,

Dave

Can't wait to see the "tags" on this one!:D
Like when Nico would sometimes run 40-50% sag on his Sunn bikes? Maybe just to gain maximum amounts of traction.
 

dw

Wiffle Ball ninja
Sep 10, 2001
2,943
0
MV
Like when Nico would sometimes run 40-50% sag on his Sunn bikes? Maybe just to gain maximum amounts of traction.
Perhaps.. Another thing to consider, how much travel did those bikes have? How much mechanical trail at static? I held one at Eurobike and it reminded me more of a heavy slalom bike than a current DH bike to me.
 

Steve M

Turbo Monkey
Mar 3, 2007
1,992
45
Whistler
Additionally, sometimes faster guys will need to run slightly more HSC, but not a drastic amount. LSC will not change and is largely tuned based on rider weight and more importantly the style of the rider (finesse -vs- gorilla).
I'm inclined to disagree with this one to some degree; for a bike's suspension response to be optimised, the vibration response should be optimised, which in turn means displacement transmissibility needs to be comparable. When the forcing frequency at the tyre is higher (on average), the damped and undamped natural frequencies of the suspension needs to be higher too, which means as you say stiffer spring rates, but also heavier damping (in both directions, theoretically proportional to the square root of the increase in spring rate) in order to keep the damping ratios similar and not develop weird handling issues (excessive peak spring forces, lack of energy dissipation in the compression stroke etc) from it.

In my own experience, and in theory, heavier springs need to be matched with heavier damping in all regards when the rider's speed picks up. It may only be a click or two though, as you say, it's not necessarily an enormous change.
 
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chup29

Chimp
Sep 9, 2009
70
3
Ashland
a good rule of thumb that i found out is that you should set it soft enough to bottom out once per run in a race setting - back when i fancied myself one of the serious and quick kids than the dude goofing around with his friends - i used to carry a shock pump (i have boxxer wc's) down the track with me on the second run to the hardest front impact and then spend 30 minutes setting it up right, now though - i set it how i like it on the trails i ride and then dont really fiddle with it... instead i occupy myself with "pro call-outs"(anyone who has seen the movie "Gnar" will know what this is... and they should be doing it too - its pretty much the most hilarious thing ever...) and beating my chest like a gorilla in the race line to freak out my competitors... it is oddly successful...
 

dw

Wiffle Ball ninja
Sep 10, 2001
2,943
0
MV
I'm inclined to disagree with this one to some degree; for a bike's suspension response to be optimised, the vibration response should be optimised, which in turn means displacement transmissibility needs to be comparable. When the forcing frequency at the tyre is higher (on average), the damped and undamped natural frequencies of the suspension needs to be higher too, which means as you say stiffer spring rates, but also heavier damping (in both directions, theoretically proportional to the square root of the increase in spring rate) in order to keep the damping ratios similar and not develop weird handling issues (excessive peak spring forces, lack of energy dissipation in the compression stroke etc) from it.

In my own experience, and in theory, heavier springs need to be matched with heavier damping in all regards when the rider's speed picks up. It may only be a click or two though, as you say, it's not necessarily an enormous change.
We are saying the same thing I think, I just tried to put it in the least complex way that I could with the hope that people reading it could understand. He was asking a general question, I just wanted to give a general answer, nothing more. Not trying to rewrite Millliken over here! :)

On the Milliken front; One thing that I think needs to be appreciated with regards to transmissibility and LSC is that the real world bicycle has a much higher ratio of sprung mass to unsprung mass than other vehicles that we analyze in a classroom setting. When you start looking at the graphs (for bicycle levels of sprung to unsprung mass ratios) of transmissibility versus suspension response in Hz, you see that the transmissibility between different damping ratios are essentially equivalent at lower frequencies. In other words, ideally, the LSC circuit is just set up to deal with "weight transfer requirements of the course, and rider style" as I wrote earlier.
 

dw

Wiffle Ball ninja
Sep 10, 2001
2,943
0
MV
In my own experience, and in theory, heavier springs need to be matched with heavier damping in all regards when the rider's speed picks up. It may only be a click or two though, as you say, it's not necessarily an enormous change.
I wanted to quote this part separately because it gets a little deeper into my main point. The resolution on a HSC clicker on many bike shocks is great enough that for two riders, one 50# heavier than the other, both going the same speed, many times the added HSC requirement is less than one click. Tested on the dyno, data acquisition, and test riders. You can take that to the bank. Two additional clicks of HSC on a typical MTB damper is an IMMENSE amount.

Yes I am speaking in generalities and not using the names of actual dampers on purpose.

Dave
 

SCARY

Not long enough
Wow,great posts...except for socket....I have no clue what he said.My goal is to use"displacement transmissibility " in a sentence on Monday,and see if I can get away with it.
I've heard the "use all the suspension once or twice in a run" for a long time.The problem with that is that is kinda sux the other 70% of the course,for me anyway.I always seem to have 1"left over.Maybe in case I screw up,it'll help.I don't know,just when I set it up the way I like,that's what happens.(I'm speaking forks,the shock pretty much stays the same once I'm comfy on it)Maybe I'm underestimating the shock,the CCDB seems amazing once it's set up,and seems to almost "self adjust"it rides so well over a wide variety of terrain.
 
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ustemuf

Monkey
Apr 8, 2010
198
15
Bay Area
I'm pretty sure the faster you go, the stiffer you need. And chances are if it's too stiff, you aren't riding fast enough :)
 

gemini2k

Turbo Monkey
Jul 31, 2005
3,526
117
San Francisco
I've heard the "use all the suspension once or twice in a run" for a long time.The problem with that is that is kinda sux the other 70% of the course
I agree. I think that "bottom your fork at least once a run" has the be the dumbest idea ever.
 

htrdoug

Chimp
Nov 25, 2001
66
0
So.Indiana
...I've heard the "use all the suspension once or twice in a run" for a long time.The problem with that is that is kinda sux the other 70% of the course,for me anyway.I always seem to have 1"left over.Maybe in case I screw up,it'll help.I don't know,just when I set it up the way I like,that's what happens.(I'm speaking forks,the shock pretty much stays the same once I'm comfy on it)Maybe I'm underestimating the shock,the CCDB seems amazing once it's set up,and seems to almost "self adjust"it rides so well over a wide variety of terrain.


It's most important to set the suspension for the best performance over the entire length of the course, If you don't use all your travel on some courses so be it. If you have one big jump that requires mega stiff suspension possibly it may be quicker overall to ease up for that one obstacle to allow you to run the rest of the trail the fastest.


I'm no engineer but I kinda disagree with the concept of mitigating the variations in tire load to increase traction(with all due respects!!!) that may apply to NAZCAR but with all the variations in offroad riding it's kinda nice to be able to force the front tire into the terrain to momentarily increase traction due to increased load. I do think keeping the tire on the ground is very important also but if the spring rate and damping are too soft the tire will hop and skip out from under you in corners even if you get forward to weight it(think SSV Marzocchi here,when softened enough not to spike on high speed hits they have zero low speed damping in either direction and will skip out in any choppy turn and you can't possibly weight the front enough to compensate) Again,I ain't got me any of that there formal education,but have ridden and race dirt bikes for 40 years, and with no natural ability I have always had to spend lots of time tuning my junk to be able to keep up with the damn A and AA level riders that I always seemed to be riding with for any length of time.
 

dw

Wiffle Ball ninja
Sep 10, 2001
2,943
0
MV
I'm no engineer but I kinda disagree with the concept of mitigating the variations in tire load to increase traction(with all due respects!!!)
I understand that the concept may be alien, but to a tire engineer this is gospel. When you look at the dynamics of traction, tire to ground, asphalt, pavement, grass, etc.. Tires break traction due to variations in tire load. These are not my words. This is the accepted reality in the field of vehicle dynamics.

It is what it is.
 

htrdoug

Chimp
Nov 25, 2001
66
0
So.Indiana
I understand that the concept may be alien, but to a tire engineer this is gospel. When you look at the dynamics of traction, tire to ground, asphalt, pavement, grass, etc.. Tires break traction due to variations in tire load. These are not my words. This is the accepted reality in the field of vehicle dynamics.

It is what it is.

After seeing what is offered as automotive tires these days I ain't too impressed by tire engineers lately...treads chop up,tire are coarse,noisy POS no matter how much you spend on them(I actually see better wear and comfort on cheap tires than high dollar ones,Michelin being the exception,they seem to wear well)

Is the variation they are speaking of a momentary drop off of load or too much load folding the tread over? I'd think that if the fork was too stiff for the tire to follow the ground or so soft it bounced up in the air after a bump either way you'll loose traction due the unloaded tread.


I like to tune the spring rate and preload to allow the front end to settle into a good geometry for turning on a smooth turn either banked or flat depending on the trail I'm riding then tune the compression and rebound damping to allow the tire to follow the ground and maintain my proper geometry while doing so,then I work out the bottom out resistance I need. Sometimes I then need to go back to the start again to get back to proper turning with the new damping setting,usually about the time I finally get it dialed I get the hots for a new bike...
 

SCARY

Not long enough
So,what does that mean if I usually run 35 in front and 40 in the rear?Physiologically I know I can hit stuff harder and not worry about flatting,but I give up some in certain corners.But that's a baseline I use and usually adjust the front depending on terrain and corners.
Also, the tires have to be pretty new in order for it to work.You really on the tread itself more than tire conformation....I could also be completely out to lunch,too.That is also an option and a distinct possibility.
 

Udi

RM Chief Ornithologist: “I Brake for Birds”
Mar 14, 2005
4,882
1,131
If you're running 35/40psi then I'd forget all about suspension for the time being, and either run thicker/heavier tubes so you can run lower pressures and/or work on being smoother. I think those pressure are too high for going fast down most DH courses, unless you weigh a tonne and your courses are all hardpack.

I honestly think 250-280g is a safe minimum for rear tubes, and maybe not much lower than 230g in the front. This is not a stab at you, but I see so many people running XC tubes / tubeless / etc and sacrificing performance (either in the way of excess pressure or getting flats) for weight.
 

toowacky

Monkey
Feb 20, 2010
200
4
Pac NW
Here's a good perspective on this:

MSA Rider's Setups

The pros all run stiffer set ups due to the higher speeds in which they are traveling and the need to keep their bikes moving forward as efficiently as possible. But they all said that they have "play" settings for when they are not racing or holding on for dear life.
 

dw

Wiffle Ball ninja
Sep 10, 2001
2,943
0
MV
After seeing what is offered as automotive tires these days I ain't too impressed by tire engineers lately...treads chop up,tire are coarse,noisy POS no matter how much you spend on them(I actually see better wear and comfort on cheap tires than high dollar ones,Michelin being the exception,they seem to wear well)

Is the variation they are speaking of a momentary drop off of load or too much load folding the tread over? I'd think that if the fork was too stiff for the tire to follow the ground or so soft it bounced up in the air after a bump either way you'll loose traction due the unloaded tread.


I like to tune the spring rate and preload to allow the front end to settle into a good geometry for turning on a smooth turn either banked or flat depending on the trail I'm riding then tune the compression and rebound damping to allow the tire to follow the ground and maintain my proper geometry while doing so,then I work out the bottom out resistance I need. Sometimes I then need to go back to the start again to get back to proper turning with the new damping setting,usually about the time I finally get it dialed I get the hots for a new bike...
Have to head out of the office, time to go ride! Tony Foale does a great job describing the basics of this in an understandable fashion in his book. You can buy it at tonyfoale.com.
 

SCARY

Not long enough
If you're running 35/40psi then I'd forget all about suspension for the time being, and either run thicker/heavier tubes so you can run lower pressures and/or work on being smoother. I think those pressure are too high for going fast down most DH courses, unless you weigh a tonne and your courses are all hardpack.

I honestly think 250-280g is a safe minimum for rear tubes, and maybe not much lower than 230g in the front. This is not a stab at you, but I see so many people running XC tubes / tubeless / etc and sacrificing performance (either in the way of excess pressure or getting flats) for weight.
I used to run the gamut from 17 psi to 30.After I got used to it,and having to ride a little looser with the higher psi-it ain't worth getting a flat on the race I just spent $1000 to attend.Just cause I missed my perfect line and nailed a rock instead of float it.I've blown more races from flats than I can remember.I'm pretty much in my racing end times....I've really liked not having a flat in 2 years.
 

Rhubarb

Monkey
Jan 11, 2009
384
174
Here's a good perspective on this:

MSA Rider's Setups

I dont have a RC4 so it would be interesting to know how many clicks of adjustment it has to make a comparason. They turn in fully then back out. Without knowing how many clicks are available it is hard to know how much compression they are using. Custom valving comparason was interesting though.
 

Steve M

Turbo Monkey
Mar 3, 2007
1,992
45
Whistler
We are saying the same thing I think, I just tried to put it in the least complex way that I could with the hope that people reading it could understand. He was asking a general question, I just wanted to give a general answer, nothing more. Not trying to rewrite Millliken over here! :)

On the Milliken front; One thing that I think needs to be appreciated with regards to transmissibility and LSC is that the real world bicycle has a much higher ratio of sprung mass to unsprung mass than other vehicles that we analyze in a classroom setting. When you start looking at the graphs (for bicycle levels of sprung to unsprung mass ratios) of transmissibility versus suspension response in Hz, you see that the transmissibility between different damping ratios are essentially equivalent at lower frequencies. In other words, ideally, the LSC circuit is just set up to deal with "weight transfer requirements of the course, and rider style" as I wrote earlier.
I dunno about that, FFTs I've done haven't shown that the input frequencies are all that high that you could forget about LSC; and even then, frequency analysis doesn't tell you anything specific about velocity, so it's hard to pick out the different effects of HSC from LSC. The effective sprung mass of the bike is essentially variable because the rider moves too, in effect giving you a 3-degree-of-freedom suspension system (once you account for the tyre, mechanical suspension and the rider) vs the typical 2 of any other vehicle, which in essence reduces the sprung to unsprung mass ratio; on really high speed hits, the rider could be better represented mathematically as a constant force acting on the bars and pedals rather than a rigid body! For what it's worth, I actually built a post shaker and tested this stuff for real for my thesis (this involved a fairly dodgy home-made apparatus shaking my rear wheel up and down like crazy with me aboard while my front axle was mounted on a tripod in my uni's FSAE garage!). The human body can in no way be considered a rigid body mass in terms of suspension!

My point, at the end of all the technobabble, is that when you ride faster, you slam into stuff harder, which means you need more to resist it. A 10% faster rider has 21% more kinetic energy that needs to be stored or dissipated within the same suspension displacement, and if you only rely on the spring and rebound damper to do that, you end up generating excessive peak spring forces that start making the bike kick more off every lip (which typically you need LESS of, the faster you are). When you hit a corner or g-out that much faster, a stiffer spring will affect your peak suspension compression, but it doesn't have such a significant effect on the speed the suspension compresses at, and thus on its own doesn't provide the same ability to reduce the overshoot of the suspension. Riding faster requires more LSC to keep the handling of the bike predictable IMO. This is based on my personal experience as well as data acquisition and small-sample statistical analysis of timed sections of track.
 
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kidwoo

Artisanal Tweet Curator
Aug 25, 2003
30,011
6,147
The old timey times
For what it's worth, I actually built a post shaker and tested this stuff for real for my thesis (this involved a fairly dodgy home-made apparatus shaking my rear wheel up and down like crazy with me aboard while my front axle was mounted on a tripod in my uni's FSAE garage!). The human body can in no way be considered a rigid body mass in terms of suspension!
Gonna need a video of this.
 

aaronjb

Monkey
Jul 22, 2010
743
256
[snip]

Again,I ain't got me any of that there formal education,but have ridden and race dirt bikes for 40 years, and with no natural ability I have always had to spend lots of time tuning my junk to be able to keep up with the damn A and AA level riders that I always seemed to be riding with for any length of time.
How did this get missed?
 
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IH8Rice

I'm Mr. Negative! I Fail!
Aug 2, 2008
24,525
493
Im over here now
I used to run the gamut from 17 psi to 30.After I got used to it,and having to ride a little looser with the higher psi-it ain't worth getting a flat on the race I just spent $1000 to attend.Just cause I missed my perfect line and nailed a rock instead of float it.I've blown more races from flats than I can remember.I'm pretty much in my racing end times....I've really liked not having a flat in 2 years.
i agree. for the one local mountain i ride, i run 40psi with DH tubes since its so damn hardpacked and none of the rocks move if you make a mistake. id rather have the higher psi then worry about changing tubes. though running this high of psi does make my suspension obviously act completely different then if i was running a much lower psi.
 

dw

Wiffle Ball ninja
Sep 10, 2001
2,943
0
MV
I dunno about that, FFTs I've done haven't shown that the input frequencies are all that high that you could forget about LSC; and even then, frequency analysis doesn't tell you anything specific about velocity, so it's hard to pick out the different effects of HSC from LSC. The effective sprung mass of the bike is essentially variable because the rider moves too, in effect giving you a 3-degree-of-freedom suspension system (once you account for the tyre, mechanical suspension and the rider) vs the typical 2 of any other vehicle, which in essence reduces the sprung to unsprung mass ratio; on really high speed hits, the rider could be better represented mathematically as a constant force acting on the bars and pedals rather than a rigid body! For what it's worth, I actually built a post shaker and tested this stuff for real for my thesis (this involved a fairly dodgy home-made apparatus shaking my rear wheel up and down like crazy with me aboard while my front axle was mounted on a tripod in my uni's FSAE garage!). The human body can in no way be considered a rigid body mass in terms of suspension!

My point, at the end of all the technobabble, is that when you ride faster, you slam into stuff harder, which means you need more to resist it. A 10% faster rider has 21% more kinetic energy that needs to be stored or dissipated within the same suspension displacement, and if you only rely on the spring and rebound damper to do that, you end up generating excessive peak spring forces that start making the bike kick more off every lip (which typically you need LESS of, the faster you are). When you hit a corner or g-out that much faster, a stiffer spring will affect your peak suspension compression, but it doesn't have such a significant effect on the speed the suspension compresses at, and thus on its own doesn't provide the same ability to reduce the overshoot of the suspension. Riding faster requires more LSC to keep the handling of the bike predictable IMO. This is based on my personal experience as well as data acquisition and small-sample statistical analysis of timed sections of track.
I think that we are making two entirely different points but it is an interesting discussion nonetheless. Although entirely different than what you are talking about, my point is that LSC has a threshold at which it no longer becomes an effective method of controlling shaft movement. That threshold has a velocity, and that velocity is overcome by the vast majority of square edged bumps. Point being that at high shaft velocities, the high speed circuits and compression shim stack are doing the majority of the work, while the low speed adjuster is just "choked off" becuase the flow rates are higher than it can handle.

I'm not sure what you are looking at for data, but I'd be willing to go on a limb and say that I've taken more of it than just about anyone working in bicycles and there is no doubt in my mind that the LSC circuits on modet downhill dampers that I've tested are maxed out at what I would consider low shaft velocities. Furthermore, I can't see the benefit of transitioning to the high speed stack at a lower shaft velocity for faster riders, which is effectively what adding LSC does.

Don't get me wrong, I love the idea of using a balanced approach of spring and damping to control chassis movement and energy storage / dissipation, that dual progressive leverage ratio curve that the dwDHR and Revolt use goes a long way to that. I just have identified that there are limits to what can be done with current dampers.
 

dw

Wiffle Ball ninja
Sep 10, 2001
2,943
0
MV
After seeing what is offered as automotive tires these days I ain't too impressed by tire engineers lately....
In the process of moving so no time for internet today but you don't happen to be an F1 fan, are you? I can see your point if you are :D
 

Pslide

Turbo Monkey
Here's a good perspective on this:

MSA Rider's Setups
Here's what I take away from that article:

Gwin, HSC: 4 clicks
Gee, HSC: 7 clicks
Leov, HSC: 9 clicks

There's no hard rule, it's your preference. Run what feels good to you.

As humans, we are remarkably adaptable. What is right for you might not be right for someone else because of sooooooo many variables, from bike to riding style to perception to what makes you feel most comfortable and confident to terrain to tire pressure and on and on...

I do believe that generally the pros run stiffer setups for the reasons described. And we know those setups are less forgiving to mistakes and weaker riders.

The awesome thing is that our suspension is now so tuneable we should all be able to find the settings we like. As for the question if your settings are right for you, or could you be going faster...those are not easy questions to answer! And I wouldn't take advice from anyone over the internet, because they don't have your perception and they are not aware of all the variables that influence your runs. Just experiment and see what works for you.

I don't think there is any unified theory of everything when it comes to suspension settings. Just look at the differences in the fastest pros bikes. They are all making different designs and settings go equally fast...depending on their own preferences.

Just my thoughts!

[/rambling]
 

big-ted

Danced with A, attacked by C, fired by D.
Sep 27, 2005
1,400
47
Vancouver, BC
I dunno about that, FFTs I've done haven't shown that the input frequencies are all that high that you could forget about LSC; and even then, frequency analysis doesn't tell you anything specific about velocity, so it's hard to pick out the different effects of HSC from LSC. The effective sprung mass of the bike is essentially variable because the rider moves too, in effect giving you a 3-degree-of-freedom suspension system (once you account for the tyre, mechanical suspension and the rider) vs the typical 2 of any other vehicle, which in essence reduces the sprung to unsprung mass ratio; on really high speed hits, the rider could be better represented mathematically as a constant force acting on the bars and pedals rather than a rigid body! For what it's worth, I actually built a post shaker and tested this stuff for real for my thesis (this involved a fairly dodgy home-made apparatus shaking my rear wheel up and down like crazy with me aboard while my front axle was mounted on a tripod in my uni's FSAE garage!). The human body can in no way be considered a rigid body mass in terms of suspension!

My point, at the end of all the technobabble, is that when you ride faster, you slam into stuff harder, which means you need more to resist it. A 10% faster rider has 21% more kinetic energy that needs to be stored or dissipated within the same suspension displacement, and if you only rely on the spring and rebound damper to do that, you end up generating excessive peak spring forces that start making the bike kick more off every lip (which typically you need LESS of, the faster you are). When you hit a corner or g-out that much faster, a stiffer spring will affect your peak suspension compression, but it doesn't have such a significant effect on the speed the suspension compresses at, and thus on its own doesn't provide the same ability to reduce the overshoot of the suspension. Riding faster requires more LSC to keep the handling of the bike predictable IMO. This is based on my personal experience as well as data acquisition and small-sample statistical analysis of timed sections of track.
Interesting. Link to thesis? Feel free to PM me...

You mention you've done FFT analysis of dyno data. How applicable is this? I mean, for a square wave input, which I approximate as an extreme of braking bumps, an FFT is going to give you a LOT of frequencies that don't correspond to actual observed shaft velocities, no? (The FFT of a square wave being an infinite sum of harmonics, albeit decaying in amplitude with the order of the harmonic...) I guess my point is that the FT gives you the rate of change of phase. It's not clear to me how this pertains to our particular problem, but rather, should we not be interested in a rate of change of amplitude, ie: shaft velocities?

I'm curious as to how disparate the shaft velocities are between trail irregularities (bumps etc, that, ideally, we want the suspension to be compliant over) and weight transfers (pedaling, cornering, compressions etc, that, ideally, I would assume we want the suspension to be less compliant over). In an ideal world it would be nice if we could tune the LSC to act solely on the latter range of shaft velocities, and HSC to act on the former, but obviously in real life this isn't possible due to overlap, roll-off in the response of the damping circuits etc. Just curious as to how much of a "losing battle" we're fighting here!
 
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SCARY

Not long enough
I really dont understand this but ,the guys at intense seemingly disagree with their own CCDB chart as far as realworld recommended springrate.

I also talked to Malcolm,and he suggested a50# different rate....almost on the cusp of 100# different rate!

If anyone has the realworld verdict to help out before this thing ships out,that would be great.

I'm 185ish ,on a L m9,extremely fast..and I think alot about racing and what races Id like to get to,but never get there.
 

IH8Rice

I'm Mr. Negative! I Fail!
Aug 2, 2008
24,525
493
Im over here now
I really dont understand this but ,the guys at intense seemingly disagree with their own CCDB chart as far as realworld recommended springrate.

I also talked to Malcolm,and he suggested a50# different rate....almost on the cusp of 100# different rate!

If anyone has the realworld verdict to help out before this thing ships out,that would be great.

I'm 185ish ,on a L m9,extremely fast..and I think alot about racing and what races Id like to get to,but never get there.
i went with their spring rate from the chart and its spot on...in both the 8.5/9 and 9.5" settings, the recommended spring rate was correct.
im 220ish and using a 450Ti and 500steel spring for the different travel settings
 
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p-spec

Turbo Monkey
May 2, 2004
1,278
1
quebec
i went with their spring rate and its spot on...in both the 8.5/9 and 9.5" settings, the recommended spring rate was correct.
im 220ish and using a 450Ti and 500steel spring for the different travel settings
this is fantastic to know.

My 400 bucks me in 9" cause im 170 dry.

got a 350 in the mail somewhere.....