Skipping - suspension set up question

Steve M · Apr 18, 2009

Whoops said:
Ok - dumb question alert...

Recently I've been hearing (and that doesn't mean its a recent trend) that the fast boys and girls on the race scene are setting bikes up with spring and damping rates that are way high - i.e. compared to older set ups would be considered over-sprung and over-damped.

The theory put forward is something like that it;

gives more pitch control (especially vs dive under braking)

allows the bike to skip over the ground rather than track it

Way to many year (throw back to car racing) of thinking about suspension being there to keep the tyre in contact with the ground as much as possible makes me think this is completely bonkers... but the counter point is that the ratio of unsprung mass and bike to rider mass is so far away from cars that it's better to skip than track the ground...

Does this make any sense? Any fast pro riders out there got any comment? If it is the new hotness for the pros, is it totally in appropriate for a weekend warrior mid pack in the sport class punter to go for a setup like this?

Cheers

Ok, I'm not a super fast pro or anything, but I consider myself at least competent. In response to the bold highlighted part - in my opinion, no, it's not appropriate for everyone. The average punter typically stands to benefit more from a smoother ride with less harshness, than they do from a setup that lets them push the tyres harder in corners, simply because IMO a large part of the fear for most people comes from the bike shaking violently in rough stuff. The problem, as you get faster, is that all those low to mid-speed hits that you take, like corners, dips, g-outs, big ruts etc get to be a bigger and bigger destabilising input on the bike, and as a result, you need more resistance in order that the bike doesn't dive like crazy, blow through its travel, bottom out repeatedly etc. Less movement in the suspension also means less change in the geometry, which starts becoming more and more noticeable as you try to corner harder, because the more the suspension and geometry change, the more your body has to deal with the changes. Search "center of traction" on here, DW made some references to it a while back, it's an interesting concept. If you're not pushing the bike that hard in corners, or hitting stuff that fast, you don't NEED the stiffer spring/compression rates.

Personally, I don't think skipping over the ground is a great thing. It should be minimised, but with consideration given to stability as well. Running rebound too slow (or waaaay too fast... but normally you get other issues before this point), or poor damper curves (bad combinations of HSC and LSC, namely too much of either and not enough of the other) can contribute to this. I personally don't believe it's necessary to have a bike that chatters like crazy through braking bumps or fast rough sections in order to have a stable bike. Sometimes it's unavoidable, but some setups are just plain bad.

Interested to hear from anyone up the pointy end of the pro field though. I'm inclined to think that at the end of the day, the rider makes so much more difference than even the best vs worst suspension setups though.

Edit: I should mention also, that my own tendency to push for stiffer/heavier damped setups is also partially a reflection of the fact that I'm a heavy guy @ 94kg or so. A lot of typical compression setups, for example, just don't have the range to cope with the fact that I am heavy AND I like a lot of compression even relative to my own weight - one or the other maybe (sometimes not though), but both in tandem requires a very heavy compression tune compared to what most people need/want/like. A lot of perception of what's stiff/soft and heavily/lightly damped is IMO relative to what your mates etc may run, who might be a long way off on the weight scale from what you are. Guys who weigh 65kg just aren't going to need anything like the same spring/damping rates as us fat boys.

top_dog · Apr 18, 2009

For the first paragraph there Steve I thought you were agreeing with Chris Porter.

As an aside a skippy bike is definitely quicker in a straight line over rough stuff. My brother and I as a little experiment did a roll comparison, no pedaling, same tyre pressures, his bike a ground hugger, mine is skippy and I made a ridiculous amount of ground on him. Mine has a higher pivot though, 224 Vs Glory.

Rider15 · Apr 18, 2009

I am by no means a pro level rider so my question is how will you know when you will benefit from a stiffer setup? Is there some speed threshold that once you pass that you will benefit? When you say you will be able to corner harder. I assume thats being able to corner more aggressively before washing out? How will you that you could stop the washing out by stiffining the suspension?

Also I would of thought that at higher speeds you tend to skipp over stuff more anyway.

Iridemtb · Apr 18, 2009

I am not a pro, but I can use my brain... Obviously stiffer suspension and higher speeds both alone help one skip over objects. It helps jumping too I bet, except for scrubing where you want the suspension to collapse a little. If you stiffen up your suspension, you better be smooth and be accurate, because while it will make you faster, you will be compromising control and being "forgiven".

Say you get off line going 25mph in a rock garden with soccer ball size rocks. Well yea, you could skip over them, but if you drift off to the side a little, your in a heap load of trouble, because you will get bucked.

Some pro's probably ride their suspension stiffer too because of their riding style. Look at same and some of the other guys, if they had their suspenion soft, they would blow through their travel, the geo would get to crazy to often on small g outs/gnarly rock gardens, etc...

Look at 45.8:
http://www.pinkbike.com/video/50631/
^^^^^^^^^^^^^^
Sorry to use a prime prosaic example, but you can see, if same had his suspension not very stiff, going that fast, he could have gone OTB.

Look at 59 into the video:
http://www.pinkbike.com/video/9751/
^^^^^^^^^^^^^^^^^^^^^
You can see him jump from one rock to another, obviosly stiffer suspension helps hop to, I know I bunny hop stuff in rock gardens sometimes.

Take it for what it is worth. Weekend warrior, have fun, don't get hurt for work next monday. But if you want to get fast, this will help, just don't over do it. Yes, I am not a guru, these are just my observances.

Kanye West · Apr 18, 2009

It's faster if they're only hitting every 4th or 5th bump rather than sinking lower into the rocks and having to take every single one. Most importantly the suspension needs to keep a perfectly level attitude when it's being ridden like that.

norbar · Apr 18, 2009

Socket said:
Edit: I should mention also, that my own tendency to push for stiffer/heavier damped setups is also partially a reflection of the fact that I'm a heavy guy @ 94kg or so. A lot of typical compression setups, for example, just don't have the range to cope with the fact that I am heavy AND I like a lot of compression even relative to my own weight - one or the other maybe (sometimes not though), but both in tandem requires a very heavy compression tune compared to what most people need/want/like. A lot of perception of what's stiff/soft and heavily/lightly damped is IMO relative to what your mates etc may run, who might be a long way off on the weight scale from what you are. Guys who weigh 65kg just aren't going to need anything like the same spring/damping rates as us fat boys.

I don't think it's only weight and mostly personal preferance. I weight around 70kg now and I often use much more compression damping than most of the guys I know compared to what we weight(I also remember an interview with JD Swanguen saing that his bike is setup rather stiff and hard or sth along the lines so I'm not the only one with such ideas). I'm sure I don't run as much as the heavier guys but considering my weight I run quite a bit and some "parking lot testers" don't like it. On early levers of riding I don't think it makes sense to overdamp the bike but when you will be able to make a conscious decision about your riding style I'm sure you will know what to chose. Forums won't help you in that. Just change your suspension setup whenever you think it could feel better for you.

pelo · Apr 18, 2009

Stiff is the way to go. Sag brings out the excitement.

DirtyMike · Apr 18, 2009

I think it has more to do with what course your running more than anything else

BigHitComp04 · Apr 18, 2009

I think what other people are saying is generally right. I think for pros the stiffer setup may benefit. But for other riders the plusher setup will make them more comfortable and will probably benefit from it. Also, i think it depends on what you are riding. For instance, i have recently setup my suspension a bit more plush and i noticed a HUGE difference in my cornering, wheels track way better and i can rail flat corners better. I think if i had my suspension set up stiffer i wouldnt feel as comfortable through corners like that, although i may go faster in a straight line with the stiffer setup.

Avy Rider · Apr 18, 2009

Watch motocross riders skip across the tops of whoops vs going slower and riding up and down in them. The faster method feels just as smooth to the riders with correct suspension tuning.

It's always a balancing act between control on rough terrain and cornering/bike handling. Generally speaking, the faster a rider attacks a course, the stiffer the valving needs to be to maintain the bikes geometry and handling.
When Craig at Avalanche asks about your level of ability he is trying to establish how fast you will be hitting bumps and he'll tune the shim stacks accordingly. What works well for one rider, might feel like hell for a slower, less confident one. (Like me! lol)

ChrisKring · Apr 18, 2009

greater speed requires more compression damping assuming the same course.

Spring rate is more a function of weight.

DirtyMike · Apr 18, 2009

Avy Rider said:
Watch motocross riders skip across the tops of whoops vs going slower and riding up and down in them. The faster method feels just as smooth to the riders with correct suspension tuning.
.

Thats not exactly a good comparision, Ive been able to stay on top of the woops on a moto by staying on the throttle more as well and balancing, while still having a softer suspension.

I can see how a stiffer suspension will help for certain situations, but I still belive it depends on the course more than anything. If you are comfy with changing your settings's, then great stiffen it when you need, If your not comfy with that, stick with keeping it softer for your all around.

About having a heavier spring...... Yeah, I call that the Placebo effect, someone said its better, they spent the money, they feel its better. I have found in DH that By far downward travel is absolutly as important as upward travel.

Demomonkey · Apr 19, 2009

Whoops said:
most likely I'm just not fast enough to get to the speed on the rough bit for it to be an advantage.

I think you hit the nail on the head

irate2:

But as someone who is marginally slower than you, you might agree that I am faster on the Commencal than the SX.

Kanye West · Apr 19, 2009

Stiffer suspension does not = slower damping.

no skid marks · Apr 19, 2009

Watching the world cup in SA, the rear ends of most bikes did seem to be skipping a lot. I just thought they were on low pivot bikes, but maybe there is a wave of stiff suspension trend coming on. Great if you're in control, but f*** it bites you in the arse if you let it take control.
Whoever mentioned the 224 and Glory above, I'd say they have very similar axle paths(pivot(VPP) points), no I've not mapped them, etc, and no they'd not be identical, but close I'd say. Affect of the rear brake would possibly make more difference.

djamgils · Apr 19, 2009

something is confusing me and some people have mentioned it.
what is meant with stiffer suspension?
-I would think that stiffer is a higher springrate.
-and more stability means more damping (to a certain extent) but this doesnt give you stiffer suspension.

To gain more high speed stability I dont think you should increase the springrate but increase damping. Like Chriskring said, springrate is a function of weight mostly.

Demomonkey · Apr 19, 2009

Whoops said:
Haha. I wish it weren't so. All those years questing for super plushness and buttery full travel motion..gone, like tears in the rain. (10 points for the first to get the reference).

Yes you do seem to be quicker... must be some of that Andorran magic.

I think what might be the proper thing to do, is to try the variables, then decide.

That "Andorran magic" has never seen me happier.

buckoW · Apr 19, 2009

Interesting topic here. Yesterday I threw on a stock DHX coil on my bike to re-ground myself to stock compression levels. I felt like the bike was better at slow speeds but shady at high speeds. I have gotten used to the increased stability at high speeds and the stock compression made my bike feel/seem much slower more difficult to take rough lines at speed.

For the last 2-3 years, I have been riding a bunch of highly tuned Fox DHX air, coil and one day on an RC4. In the beginning, it took me a little while to get used to the increased compression but now that I am used to it it lets me go much harder into everything. If I am tired or not "on" it is not very easy to ride. I think it has a lot to do with the speeds and the riders ability to command the bike around without asking any questions. If the rider starts to "ask" rather than "tell" then the increased compression will hurt more than help in my opinion.

Increased compression definitely helps you go faster if you are pushing the limits of your current setup, IMO.

Steve M · Apr 19, 2009

Whoops said:
ok - as the original poster, I'll clear up what *I* mean (others may be talking about different things.

Over sprung and over damped.

i.e.; spring rate that's higher than factory recommendation (usually aiming for 1/3 sag). Nothing to do with preload..... AND damping rates that are higher (more) than would be required (even with the higher spring rate taken into account).

Eg instead of x lb/in spring use a 2x lb/in, and instead of y clicks of rebound and z clicks of compression use 2y and 2z.

If you really wanted to compare suspension "stiffness" you'd need to normalise spring/damping wheel rates against rider/bike suspended mass. In other words, get an output for normalised spring rate of lbs.in^-1.slug^-1 or n.m^-1.kg^-1, measured at the wheels. Sag percentage means bugger all really, except to give you some idea of the low-speed G forces required to bottom the bike out, in fact sag distance (measured at the wheel) is a more accurate means of comparison.

Anyway, as for "skipping" - it's not usually a good thing. It never will be a good thing in any situation where your tyres need grip, like braking or cornering. If your wheels aren't on the ground, they're not gripping; if the normal force at the tyres (and thus the grip) varies more, the bike becomes less predictable. However, IMO it may be the case that setting your suspension up in such a way that the bike is faster overall (heavier damping and/or spring rates) results in a setup which is more prone to skipping sometimes. In a straight line, off the brakes, then whatever works for your riding style. I have found though that the biggest influence on how fast you roll in a straight line through rough stuff is simply how heavy you are.

Comparison to MX riders in whoops is a pretty long bow to draw IMO - they have a throttle for starters, and are riding over obstacles bigger than the suspension could absorb anyway. I haven't ridden any DH tracks with any similar features (Stromlo does have that stupid concrete whoop section though, where Matti broke his wrists, but I didn't see anyone just bouncing across the top of those). The closest thing we'd ever see would be huge braking bumps, but even then I've never found any braking bump section where it seemed beneficial to bounce through.

ChrisKring · Apr 19, 2009

another thing with the moto comparison, the MX bike has a driving force at the contact patch that has the effect of stiffening the suspension. Also, whoops are low speed hits thus why you need a driving force to skim them. Chop the throttle in whoops and see what happens.

It took me a long time before I got the confidence to click it up into 4th with the throttle at 50% going into a set of whoops.

Avy Rider · Apr 19, 2009

Regarding my MX riders skipping over whoops analogy...

Not a good one but what I'm try to point out is that you can hit the faces of bumps vs dropping in and out of them with control if your suspension is set up "properly".
Now properly is the key word.

If those MX riders were running over sprung and over damped suspensions their bodies would take a pounding during those high speed skips over terrain. It's not the over damped/sprung suspensions making them skip but the actual speed and attack positions on the bike.

As was pointed out earlier, you can run a nice cushy suspension but still "skip" across the tops of bumps if you go fast enough. Who can really say how those riders suspensions are set up? Are they really over damped/sprung or do they just ride faster and that is what is causing the skipping?

P.T.W · Apr 19, 2009

My theory on this is...The main reason some of the pros set their bikes up stiffer is mainly to control the attitude of the bike an keep the geometry in their sweet spot at the insane speeds tose guys hit things....The "skipping" is just a byproduct/tradeoff not the main aim

norbar · Apr 19, 2009

P.T.W said:
My theory on this is...The main reason some of the pros set their bikes up stiffer is mainly to control the attitude of the bike an keep the geometry in their sweet spot at the insane speeds tose guys hit things....The "skipping" is just a byproduct/tradeoff not the main aim

That's exactly my thoughts. I started to use more compression damping when my bike stared going funky under heavy use and I'm still very far from a pro. Also go to a WC class track and you will find for yourself that your bike needs much stronger damping. Hitting a 50-60deg steepness into a 90deg lefturn berm will be really sketchy if you set your susp soft. If you won't be going close to such tracks I don't think even at high levels you will need that much stiffness.

BTW. I remember someone speaking about a suspension designed to skip over obstacles. Don't remember who was it about exactly. Old Sunn?

dhkid · Apr 19, 2009

^ not sure about suspension design, but if its suspension set up then it's probably that nutter chris porter.

http://www.descent-world.co.uk/index.php?option=com_content&task=view&id=339&Itemid=81

Chris Porter said:
However, most people run their rebound way too fast, scoot along a car-park without pedalling and push down on the pedals as hard as possible to bottom out front and back or as near as you can. But don't absorb the rebound stroke with your knees or ankles or arms, when you reach the bottom, instead allow your arms and legs to go stiff and adjust the rebound until you get a return to the sag point but no more, no hyper-extension and no extra oscillations. This will be a good start point. Don't flap about compression damping.... Whilst not 'un-important' it's way less important than the rebound stroke.

LMC · Apr 19, 2009

Whoops said:
Haha. I wish it weren't so. All those years questing for super plushness and buttery full travel motion..gone, like tears in the rain. (10 points for the first to get the reference).

Yes you do seem to be quicker... must be some of that Andorran magic.

the speech at the end of blade runner.. unless someone beat me to it and i didnt see?

buckoW · Apr 19, 2009

Whoops said:
Thanks.

So with this ^ comp damping, is your bike skipping over rough stuff or sticking to the ground (e.g. braking bumps.... and are you running a high spring rate than you should according to, say the TFTuned calculator?

If it is skipping - would you say it's faster (wheels not dropping into hollow and hitting rear face = decel force vector) AND more control, or only faster, or faster with less control?

I run around 30% sag.

It rides higher in the travel for most stuff but still uses full travel on very hard hits. It doesn't use lots of travel on small stuff or slow speeds if that is what you mean by skipping. It is awesome for charging into brake bumps, g-outs, corners and rough repetitive hits. At high speeds with aggressive riding it works much better so yes I would say it is faster. It makes my bike get "hung up" on hard square hits a lot less and roll over rough terrain quicker. It is not as comfortable a ride at slower speeds.

LMC · Apr 19, 2009

Whoops said:
10 points!

woo hoo!

Muttely · Apr 19, 2009

so what settings are we talking to get a nice hard setup on a DHX?

top_dog · Apr 19, 2009

dhkid said:
^ not sure about suspension design, but if its suspension set up then it's probably that nutter chris porter.

http://www.descent-world.co.uk/index.php?option=com_content&task=view&id=339&Itemid=81

But the bit about the suspension not coming back past the sag point and not over oscillating does sound pretty right. You'd want the bike to return to a steady state ASAP.

Unfortunately I'm somewhat partial to the Chris porter way of thinking...

Muttely said:
so what settings are we talking to get a nice hard setup on a DHX?

500psi

dhkid · Apr 19, 2009

if you think about what he said for setting up rebound, setting it by compressing then trying your best to make your body a dead weight, you are going to need very very fast or close to no rebound damping to get it to oscillate.

he does say there that most people run their rebound way to fast, which i dont agree with at all. most people have a fear of running fast rebound, which is just stupid.

DirtyMike · Apr 19, 2009

buckoW said:
I run around 30% sag.

It rides higher in the travel for most stuff but still uses full travel on very hard hits. It doesn't use lots of travel on small stuff or slow speeds if that is what you mean by skipping. It is awesome for charging into brake bumps, g-outs, corners and rough repetitive hits. At high speeds with aggressive riding it works much better so yes I would say it is faster. It makes my bike get "hung up" on hard square hits a lot less and roll over rough terrain quicker. It is not as comfortable a ride at slower speeds.

Sounds a little freeridish on your setup, but thats not neccessarily a bad thing. Alot fo that really has to do with your riding style, on a wide open full blown haul ass DH coarse, you probably going to want a bit more sag, for when you find those little holes you want to keep your wheels on the ground, instead of skipping of them from topping out.

My setup is right at 3 inches of sag in teh front with a 7 in fork, which is right about 40%, and in the rear I am at 3.5 in sag on what I was told is an 8.3 in travel bike<blindside> and thats also right about 40% sag. I am not much of a jumper, I like sticking to the ground and letting it fly, only jumoping if its part of the course, I can stick it pretty damn good in the brake stutter before a turn and know the tires are going to track.

As far as compression setting, The back is pretty wide open, little bit of HSC, LSC wide open<5th element shock> the platform does pretty damn good itself for LSC. For the front, I have the LSC just stiff enough that I can control the dive in a corner, and while braking. Its still a pretty plush setup and feels really comfy at both hi and low speeds, and I still have plenty of dmapening for the occasional drop or jump that is just part of the course to not destroy my body from taking a railing from a bottom out.

I think the biggest key is that you need to feel comfy with the setup, if your not comfy, your going to slow yourself down.

Skipping - suspension set up question

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