Pinkbike Poll
Most Pinkbike members ride dual-suspension bikes, so it stands to reason that the majority of us are capable of tuning our own suspension. Talking to top suspension technicians, however, about the people who they encounter at major events that are in need of advice or a quick tune, would lead one to assume that the majority of riders are ill informed about the steps required to properly set up their shock and fork. While those may seem like fightin' words, a day spent watching riders pass by a chunky section of turns and a couple of jumps at Whistler would lend credibility to their statements.
To this end, suspension makers constantly wrestle with the concept of how many adjustments and what the range of those adjustments should be included when they design a production fork or shock. Bike makers work closely with suspension companies to perfect the suspension tunes for each model, but that won't guarantee that the bikes will perform well if the end user, armed with a shock pump and a can-do attitude can twist all the knobs and create rolling barf.
Suspension makers and bike designers know that a lot of riders exist who know how to tune a suspension, and who can utilize all of the pro tuning features that bristle from their upper-level forks and shocks, but in secret meetings, they dream about the day when suspension components will require minimal tuning by customers and yet deliver the outstanding performance that they can only promise in potential now. Should suspension makers cater to the illuminated minority and stuff their shocks and forks with adjustable features, or should they embrace the common man and sell a best-case-for-this-application component with minimal tuning options? It really depends upon the customer's ability and willingness to learn.
So, how well can you tune your own suspension? A good assessment of your skills may be the number of your riding friends who ask your assistance in setting up their bikes. You be your own judge, though. Rate your abilities in this outstanding Pinkbike Poll.
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The HSC is making it resistant to the initial part (so having too much is making it harsh) however once you take this hit the shim stack is opened and then the suspension blows through its travel because the shim stack is no stiffer.
Compression dials ultimately change the thresholds of the fork, the real stiffening and support adjustments are all in the shim stack.
Ideally the best thing you can learn is how to tune a shim stack.
It's not as if being a more "hardcore" rider means that you can magically only run a "hardcore" small amount of sag. If riders are fast, then that negative travel is that much more important. Find the correct spring/sag, and get the damn shock/fork's stock "everyman's" valving tuned if it feels too soft.
Riding Rampage and guys who only huck is a different story...
I'm not saying its comfortable. In fact it can feel gross at slower speeds. But if you want to get to point A to point B the fastest, you have to stiffen up your fork.
...and always go stiffer on your spring rate first, compression damping second. This allows your fork to ramp up faster and feel supple off the start, which is what you want. If you ride into your travel too deep, it will feel over damped. This old news in the MX world, the same applies to DH mtb.
These guys don't agree though
In general HSC and LSC refer to speeds of the shaft so beginning or ending stroke shouldn't matter as that link pointed out.
So you go outside and push down on the fork and it compresses half way or more, this is still a low speed compression but clearly a big one if your using more than half travel.
However some dampers are position sensitive in where one circuit is only open once travel reaches a certain point or oil forces reach a certain point. And others are speed sensitive, So there is some variance between those that use position or speed sensitive dampers.
I wouldn't suggest you view tuning as HSC=big hits and LSC=small hits its not exactly accurate.
I actually originally mentioned the link between big bumps and the speed but opted to delete it for the fear of getting to detailed lol. In general yes there is obviously a link between the bigger the bump the more force but I think its inaccurate to explain it like that, more accurate would be big force and little force.
You can have a big force initiated over a slow velocity.
I think with big bump/little bump its easier for people to get the set up and understand it incorrectly.
if you want to keep discussion im happy to, maybe PM would be easier though.
I am actually still trying to get a feel for hsc. It is hard since you have to test it out on the trail to get a feel for it.
I learned to set rebound from Zinn: go off a bump and if you bounce up and down slow it down a little at a time til you don't then o might adjust a click or two depending on the trail: slower for smooth with big jumps, faster for chunder or extra roots.
Anyone have any recommendations, or am i doing it right?
Again not fully familiar with the wc but think changing to a softer elastomer isn't going to help you. If you are riding in super cold conditions, then you need to drop the weight of the oil in the damper, as it is most likely running thick due to the cold. However the oil warms up pretty quickly when pushed hard, so you will have to ask yourself "is my fork still feeling too hard at the end of a run, or only in the car park at the beginning of the day?" If its only in the car park, i suggest you just bounce around like a loon on your bike for a good 5 minutes before starting any real riding. If it stays slow all day "(for example, if you live somewhere like alaska), then swap to lighter oil.
I can provide a link is someone doesnt beleive that last point
I would like to see the link about oil visc. having little effect on hsc circuits. Yes heavier oil will force the shim stack to open further, meaning the damping will be less affected than a lsc circuit with fixed sized ports, but i doubt the effect would be so linear as to mean changing the oil visc. has no effect whatsoever on damping. Sounds like an interesting read tho, and I am more than ready to be wrong...
As you can see on the graph on the right oil weights only effect low speed velocity (LSC) you can read the desription below the graphs to understand why.
However I still don't think it is as clear cut as "oil viscosity only affects lsc circuits". In the link you posted they are ONLY talking about high speed circuits, so when they say "low speed" they mean "at tthe bottom end of the range of the high speed valving".
It seems that what they are trying to explain is that as the speeds increase, the effect of viscosity diminishes, so during super mega high speed impacts, the damping will be very similar for two different oil weights, but as the speeds decrease, the affect of viscosity becomes more and more prominant. It is undoubtably true that if you want to make drastic changes to your HSC the only way to do so is to change the shim stack. No amount of knob twiddling or oil weight fiddling is going to fix a shim stack that isn't right for your weight. This doesn't mean you can't use dials and oil weight to fine tune the feel, after getting the correct shim stack fitted.
Also...that link is going in my bookmarks. Thank you again!
It refers to both Low speed and high speed velocities and the effect of the shim stack, LSC forces only slightly opens the shim stack which the link also mimics that statement, when you have a highspeed hit the shim stack opens much more and therefore oil viscosity is much less and issue. Essentially the more the shim stack is opened the less the oil has an effect. Its quite apparent though in that graph that at a certain point each oil starts to level off which would indicate a wide open shim stack. Once the shim stack is open the oil will have only minor effects as you can see from the graph at about 40inchs/sec the graph drastically tappers off.
For downhill forks this point would be where the HSC stack is essentially activated and opened.
You will notice a minimal effect yes but using oil to change the HSC is not very effective mostly because any change you make to the oil will dramatically effect LSC and only minimal effect HSC.Oil is really a LSC adjustment
Now that said im not too sure when you would adjust LSC with oil or the base shim.....
The question of whether the shim stack is ever FULLY closed, depends heavily on the individual design of the damper (especially if there is any form of preload on the shim stack, but also due to many other variables.) There is also the question of how much oil the LSC circuit flows during a high speed compression, and the effect of oil viscosity on this flow. Things get extremely complicated from here on in....I think the best thing to take from the link is that oil viscosity has a LARGE effect on LSC and LESS of an effect on HSC.
As far as oil weight being adjusted to solve a prob, this is very relevant to immacaronis original question, as he stated "my forks are stiff when cold" suggesting that the cold is the culprit, and therefore lighter oil will solve his particular problem.
As far as the little fight going on between immacaroni and slidways. I don't think either of you are trolling. Nor have either of you said anything foolish. In fact slidways has made some bloody good points and immacaroni asked a perfectly reasonable question. Calm down lads...
It does depends massively on damper design, however most forks still use the shim stack for low speed compressing too most down to the base shim and orifice port size.. But whether there are other methods in the damper will depend on the effect of the oil 100%agree.
For instance I have a boxxer team so it primarily uses a 2stage shim stack so for that fork the article is pretty spot on. The article is right but you need to leave room for other varribles the damper has built in I think we both agree on that one. Yep ill agree oil has a larger effect on LSC and a minor effect in HSC. I wouldn't say it has none.
As for the OP About stiff forks get a good quality oil too something like redline or silkolene.
You want something with a high quality it will help keep the fork more consistent. Fox oils are good too for the lowers but its pricey for such a small amount.
I'ts easier to describe what knobs are than how to tune them. Each situation is different so it's verry difficult to explain things.
I'm currently wrinting a "guide" (in french) about suspensions, and the "tunning part" is the most difficult part I write.
I think it's why there is so few comprehensive guides.
I assume, where you have put "compression" you actually mean "preload/spring rate?"
And yes you did mention preload and spring rate.
1) I understand the differences between preload and spring rate. I have said nothing to suggest otherwise....
2) A higher compression setting will cause higher back pressure in the system (during the compression stroke). This is true. However seeing as the damping fluid can be viewed as essentially un-compressible, and last time i checked the lowers on my forks didn't blow up like a balloon every time i compressed my forks, this back pressure disappears as soon as the fork stops compressing, as nothing has been elastically stretched/compressed in order to store any energy. It in no way helps the fork to return to its static position. This is simple physics. The only thing that causes the fork to re-extend to its static position is the spring (and any air trapped in the system, but this is beside the point and may as well be ignored during this discussion).
3)I did mention preload and spring rate yes. They were both applicable to the situation. Increasing the spring rate or preload will require an increase in the rebound damping in order to achieve the same rebound speed for a given position in the dampers travel.
I never said that they were the same thing, or in some way interchangeable...
I love being able to pull my forks and shocks apart and rebuild them. Cheaper and much more rewarding when you are riding on something you know you can fix because you know how it works.
almost certain the Fox dampers can be re-Shimmed ... although I've read that they only utilize a few 3 shims. I haven't opened up my 40 that deep yet, But am glad info is there
service.foxracingshox.com/consumers/FOXDisclaimerUserChoice.htm
But you're right. They are pricey.
How do you know what you think you know, you know?
that said, with this method I often end up near the recommended factory setting anyway, so it must be nearly right.
Next week, I will send to him my RP23 for the same customization.
When you tasted custom suspensions, you can't come back on stocks suspensions from the box.
Same thing for my DH fork. I have a Boxxer with a custum made cartridge from the other suspension guru in France. You replace the stock cartridge by the other one which is a 4 way cartridge tune up for you and you have a damn good fork. The cartridge cost 220€. So buy a cheap boxxer rc at less than 500€, add the CR conception cartridge and for around 700€ you have a fork which is a lot better than 1600€ stock DH fork.
There's such a huge variation in riders, riding style and gear that I don't believe a reduced option set or even a 'stock tune' can cover all riders. Hell I've never bought a bike where I thought the stock tune came close to offering the ride I want. (lots of low speed compression, minimal hi-speed and just enough damping to keep my wrists on the bar and my feet on the pedals).
Some people want never to touch their suspension and others want to fiddle with almost all of it. I'm in the latter group, but then I'm practical enough to work through settings one option at a time until I reach my optimum set up.
I've ridden my fox fork all season with the rebound set like a pogo stick because the adjust broke while I was turning the knob. It was a problem only twice.
At least, if they install all new gliders, O-rings, seals and bushes in the shock, I am agree to pay 210 USD once in 4 years. (Than is only because I don't know where to buy rebuild kit for RC4)
:P
I tune and service my suspension on my own BTW
then I talked to a Norco Mech..and question him on my build.at the end of the day, all I need to do is a click here of compression/rebound, or a turn of the rear coil. done!
bike rides awesome!!
It's nice when a brand provides hsc, lsc, rebound, spring rate, volume adj, basically all the tools to personalize a 1000$ fork to the rider.
stiff run, so stiff suspension has a few advantages:
1st you have to be confident to ride high speed
2d the stiff suspension allows to run high speed otherwise the frame is moving to its travel and converts the speed to a friction and
you loose speed.
3d as u r running stiffer suspension you ve more control most of the force is absorbed by the spring and the damper and feel more stable.
4th stiff suspension do not heat up the oil that much couse you not running all the travel
to only downside is you can compromise the frame running too stiff but nowadays frames are WC ready so they r designed to run stiiff
I wonder how they home-made vacuum their rear shocks.. seeing that a single air bubble can compromise the entire suspension... plus do we wanna talk about the quality of OIL they use in it or outside temperature, type of terrain and so on.. the variables are so many that it's hard to believe that the most of the riders here can do it...
suspension engineering it's a branch of 'engineering' that means that you have to study or make a lot of experience as a (suspensions) mechanic before beeing able to actually improve the performance..
is like pretending to be a doctor..
in general I think there is a lack of culture of suspensions in MTB... in MX people has more culture for it and there are more professionals around.. and they make the real difference!
In MTB only the uCI DH teams have their suspension professional on board... and probably there's a reason.
And yeah, quality (coil)shocks are pretty much just downsized moto-shocks. Because of that it'd be nice if those established and professional moto-shops could provide dyno-charts and suspension tuning for bikes too. Maybe someday.
Small things make big difference but it's not rocket science, considering setup changes.
It's just valves or holes opening or closing anyway , more oil flow = fast , less = harder/slower.
so my question is, do you focus on the fork or the shock first? Do both at the same time? Or are they fairly independent of each other?
Suspensions aren't independant. For exemple a too firm rear schock makes the fork feel too "plush".
"Yes I enjoy servicing and tuning the suspension."
guys, changing the oil (and cleaning) in your fork and shock are the things that you "must have". that will increase your suspension life and save your money.
But I still don't know how to check the psi and use a shock pump but really need to learn because last year blew my shock at Silverstar riding like a cheetah chasing a gazill because I know my shock wasn't in the right psi.
Did you get some training at kovarik racing?