[dhkid]

i am confused on how some bikes grip amazingly and some not so... (rear traction.)

=>basic physics tells us that F(friction/traction)=U(coefficient of friction)*R(reaction force)

neglecting how the rear suspension moves your body weight around, assuming same coeficient of friction, neglecting geometry, assuming on all bikes that the reaction from the riders weight,R is constant. and assuming on flat ground(no bumps) and the tire doesn't skip, the suspension would sag and transfer that R to the tires.

=>so does that mean all bikes (within reason and following the assumptions) will have the same amount of traction on flat surfaces with out the rear wheel skipping.

but then traction on dirt surfaces is different, just for simplicity i'll assume that dirt gives a constant coefficient of friction. so it comes down to the bumps of the surface.... and how well the rear suspension reacts to the surface and how it applies the Reaction force R.

=>so i have come to the conclution that rear suspension that are firmer in the beggening of the stroke when compared to bikes which are very supple in the begining stroke will grip better.

i come to that conclution from when the suspension hits a bump, (assuming constant rebound damping on all the bikes shox) the firmer suspension designs will rebound as a faster speed because it is stiffer and given the rate is higher then the supple design and a constant rebound damping, it would rebound faster. so when a bike goes through a non perfectly smooth surface, the bike with the faster effective rebound will apply a greater total reaction force to the ground.

does this apply to when the rear tire skips in a drift too??

discuss, are my assumptions valid?

sorry if their gramma/spelling mistakes, i tend to make alot when i am focused on trying to put my point forward....

 

[Hannu]

Where it goes wrong is when you assume that all shocks have same amount of rebound damping, because that is not the case. What you need to do is assume that rebound speed on all shocks is equal, in other words rebound is tuned correctly according to spring rate. There is no point to just pick one rebound damping rate and compare different spring rates with that.

 

[dhkid]

yea, i didn't say that i assume same rider weight, suspension sag. so when i say same rebound danmping i mean same rebound speed at the shox. independent of spring rate.

 

[Honus]

In a world that works only on assumptions I don't discount what you're saying. According to your assumptions, ideally the bike that has a faster effective rebound will keep the tire contacted with the ground better- however, neglecting how the rear suspension moves your body weight around and assuming on all bikes that the reaction from the riders weight is constant changes everything. Weight transfer plays a huge role in how a suspension bike works.

So it doesn't really answer your original question.....

It's just not that simple- wheel path plays a big role here (since dampers are speed sensitive the shape of the bump to be absorbed can be more important than the size of the bump) as does frame geometry and frame rigidity (lateral as well as torsional.)

There are just too many variables here to try and negate some of them so that you can arrive at a conclusion. I think you have to look at the whole dynamics of the bike as a system. The reason why one bike grips and another doesn't can't be broken down into little individual parts and analyzed- you have to look at how the entire system works as a cohesive whole.

 

[Inclag]

i am confused on how some bikes grip amazingly and some not so... (rear traction.)

=>basic physics tells us that F(friction/traction)=U(coefficient of friction)*R(reaction force)

neglecting how the rear suspension moves your body weight around, assuming same coeficient of friction, neglecting geometry, assuming on all bikes that the reaction from the riders weight,R is constant. and assuming on flat ground(no bumps) and the tire doesn't skip, the suspension would sag and transfer that R to the tires.

=>so does that mean all bikes (within reason and following the assumptions) will have the same amount of traction on flat surfaces with out the rear wheel skipping.

but then traction on dirt surfaces is different, just for simplicity i'll assume that dirt gives a constant coefficient of friction. so it comes down to the bumps of the surface.... and how well the rear suspension reacts to the surface and how it applies the Reaction force R.

=>so i have come to the conclution that rear suspension that are firmer in the beggening of the stroke when compared to bikes which are very supple in the begining stroke will grip better.

i come to that conclution from when the suspension hits a bump, (assuming constant rebound damping on all the bikes shox) the firmer suspension designs will rebound as a faster speed because it is stiffer and given the rate is higher then the supple design and a constant rebound damping, it would rebound faster. so when a bike goes through a non perfectly smooth surface, the bike with the faster effective rebound will apply a greater total reaction force to the ground.

does this apply to when the rear tire skips in a drift too??

discuss, are my assumptions valid?

sorry if their gramma/spelling mistakes, i tend to make alot when i am focused on trying to put my point forward....

My brain just filled up with candy.

 

[dsotm]

The shock with the faster rebound will apply a greater force to the ground at specific moments, but the shock that applies a more constant reaction force (the shock that allows the tires to better conform to the ground) will provide the most traction and even more so, the more consistent traction (even more importan). The same principle applies to tires. Tires that conform to the ground better, grip better, and so less air pressure (to a point) provide better traction.

 

[mandown]

The shock with the faster rebound will apply a greater force to the ground at specific moments, but the shock that applies a more constant reaction force (the shock that allows the tires to better conform to the ground) will provide the most traction and even more so, the more consistent traction (even more importan). The same principle applies to tires. Tires that conform to the ground better, grip better, and so less air pressure (to a point) provide better traction.

good thoughts. at some point rebound that is too fast will "kick" and bounce the wheel off the ground again, the opposite of rebound that is too slow and packs up. it is about balance.

 

[Sandwich]

I think wheel path, tires, chain torque and air pressure are the most important factors regarding traction. I think your argument is physically correct, but I think you'd find that with a firmer bike, as you're saying, you'll find the rear wheel will start skipping over bumps rather than absorbing them, which further reduces traction.

Chain torque is a big deal too, pulling the wheel up (on some very low pivot designs) reduces it and pulling it down (on high pivots) helps increase traction...to a point.

Ideally, the wheel will follow every bump, up and down, keeping the tire in contact with the surface at all times. I think the goal of a bike designer is to isolate as many variables as possible (wheel path, braking, pedalling) so that the wheel can naturally follow the terrain with no outside forces.

 

[manhattanprjkt83]

this should put an end to all this discussion:

 

[ChrisKring]

A suspension that is critically damped will have the best traction. Excessive rebound force due to not enough rebound damping will cause the reaction force to put the sprung mass in motion enough to take the wheel off the ground.

To expain this to you better, take a blown out rear shock and go for a ride.

 

[ChrisKring]

See these links for an introduction to vibrations:

http://en.wikipedia.org/wiki/Damping http://www.abdn.ac.uk/physics/vpl/pendulum/underdamped.html

 

[dhkid]

honus, when i say i neglect the momevent of body weight its just to make it simpler, coz some may argue that low single pivots will move your body weight backward under corneing loads ect... its just gets too complicated after a while

so what other major things should i not neglect?

sandwich, would chain torque apply since when conering its most likely you are not pedaling.

if wheel path comes in it would make it too complicated agian....

chris king, i find with modern shoxs, even with the fastest rebound you dont get much of a pogo stick effect as just using a blown shox. might be different for hevier riders tho.

good to know that everyone agrees that the suspension design that will keep the the most total reaction force on the tires through out the corner will grip the best, that already clears up alot.

then i guess it just how a suspension will be able to achive this^^

thanks for the replies so far.

 

[Whoops]

for bikes, on dirt, with knobbly (whhoorrr) tyres friction is not the same as grip.

the tyre bites into the ground, giving a mechanical interface (as opposed to a fritional one).

 

[bullcrew]

for bikes, on dirt, with knobbly (whhoorrr) tyres friction is not the same as grip.

the tyre bites into the ground, giving a mechanical interface (as opposed to a fritional one).

Thus advancing the madula oblingata and breaking the interface equasion to the semi chromatic induction theory that applies to the overly tuned linear driven device the equals a flux capacitor.

Start twisten knobs!

 

[dsotm]

good thoughts. at some point rebound that is too fast will "kick" and bounce the wheel off the ground again, the opposite of rebound that is too slow and packs up. it is about balance.

Exactly, the shock that allows the wheel to conform to the ground best will allow for the best traction.

 

[dhkid]

for bikes, on dirt, with knobbly (whhoorrr) tyres friction is not the same as grip.

the tyre bites into the ground, giving a mechanical interface (as opposed to a fritional one).

not entirely true, otherwise softer compound tires wouldn't give more grip on dirt. roots and rocks of course, but they do help on dirt...

 

[TheInedibleHulk]

Ive always thought that the ideal suspension setup was the one that allows your tires to remain in contact with the ground for the highest possible amount of time. So an overly stiff supension that is bouncing over bumps would not be ideal. On the other hand, and overly soft suspension will wallow in its travel will also not adequately maintain tire contact, as the travel is not being utilized. I think you will find, as you examine setups from different levels of riders, that in general springs get stiffer and damping gets heavier as you move up the field. Stiffer springs gives a better feel for exactly what the tires are doing, not to mention that faster riders are hitting stuff faster and harder and therefore need more resistance to bottoming than the guy who is just putzing along. I know a couple of pros who ride absurdly stiff supension for the feel reason. I tend to fall somewhere in the middle.

On other side note, the stronger you get, the less you need your suspension. If you can take the hits and stay in control, a stiffer setup should be faster due to better effieciency for pedaling, pumping, ect.

 

[dhkid]

i have heard about the siffer set ups too, but i though it was stiffer and faster rebound...

of course when i mean stiff set up i still mean 25-30% sag, when compared to say a v10 which has 40% sag and very supple initial travel.

 

[Superdeft]

I'd see if you can find a book on motorcycle suspension, the book I've been looking at for racecar suspension generally deals with the same equations, but it comes down to keeping the wheel firmly planted on the ground as much of the time as is possible, which is why designs like the v10 often work so well people describe them as 'dead.' There's a lot of internet engineering/marketing crap around here that's just people throwing around buzzwords, so I'd go to the source of the knowledge and find a good book if you're actually looking to gain some knowledge about suspension.

 

[heikkihall]

I'd see if you can find a book on motorcycle suspension, the book I've been looking at for racecar suspension generally deals with the same equations, but it comes down to keeping the wheel firmly planted on the ground as much of the time as is possible, which is why designs like the v10 often work so well people describe them as 'dead.' There's a lot of internet engineering/marketing crap around here that's just people throwing around buzzwords, so I'd go to the source of the knowledge and find a good book if you're actually looking to gain some knowledge about suspension.

It is true that there is aot of internet engineering and marketing crap out there, but there is also alot more to downhill than cornering, braking, and the traction characteristics that are experienced during those things. As with everything there are a lot of give and takes.

I will say that the V-10 gets good traction. But it is also hard to argue that the bike does not feel dead. A bike with that much travel that is designed to be run with that much sag will be much harder to get off the ground than your typical DH bike with 8" of travel and 30% sag. But that is exactly the reason that the V-10 gets good traction, without that sag the wheel would be bouncing off the ground and losing traction more often. That is just something that the engineers at SantaCruz decided was an ok sacrafice. Some like it, some dont, and in the end it all comes down to riding style and personal preferance.

 

[RaID]

we also have to remember that sometimes getting the most traction doesnt lead to the quickest way to get down the mountain
eg skimming over stutters rather then making your bike to stick every ground part of the stutters

or take the rally car analogy, the controlled slide turns they make, not the most amount of traction yet the fastest way to travel around that corner

 

[dhkid]

dammit, its got to the point where you have to name bikes. i suspect this tread will go downhill fast...

the v10 getting good traction? i think that its less grippy then say a sunday or commencal....

 

[Whoops]

not entirely true, otherwise softer compound tires wouldn't give more grip on dirt. roots and rocks of course, but they do help on dirt...

That's why I said "on dirt"

 

[Banshee Rider]

the v10 getting good traction? i think that its less grippy then say a sunday or commencal....

You've owned one or have had extensive enough time to dial the shock for yourself and still find that it doesnt track well?.........Interesting

 

[Sandwich]

sandwich, would chain torque apply since when conering its most likely you are not pedaling.

if wheel path comes in it would make it too complicated agian....

chain torque won't matter much in a corner, you are correct, except if you have a high pivot design. Imagine if your feet/cranks are locked, the rear wheel has two options, it can lock out, or it can roll forward, neither of which is really beneficial to traction.

wheel path will make the conversation more complicated, but I think it's more important than ramping up rebound damping. In fact, I think bikes track better with faster rebound damping.

 

[Honus]

If you want a really good book on the dynamics of two wheeled vehicles read "Motorcycle Handlig and Chassis Design- The Art and Science" by Tony Foale. I've read this book cover to cover and it's probably the best book of its kind. His suspension analysis software looks pretty neat too.
http://www.tonyfoale.com/

 

[Steve M]

A suspension that is critically damped will have the best traction. Excessive rebound force due to not enough rebound damping will cause the reaction force to put the sprung mass in motion enough to take the wheel off the ground.

To expain this to you better, take a blown out rear shock and go for a ride.

I disagree. For a sinusoidal input at a constant speed blah blah, assuming you have a linear damper constant (which no shocks do) that might be the case, but what is considered "underdamped" for a rider's mass will invariably follow rough terrain the best. Underdamping will not "take the wheel off the ground" unless it's REALLY extreme given the spring rate to mass ratio (ie you're running bugger all sag and are topping out harshly), but overdamping most certainly will if the wheel can't follow the ground properly. For something like braking bumps (similar size/spacing hits) then yes there is arguably a critical point at which the suspension will be able to follow the terrain the best (where its resonant frequency is the same as that of the braking bumps) but otherwise I would most definitely err on the side of underdamping rather than overdamping.

dhkid: friction on a flat surface should be roughly the same between any bikes with the same tyres with the exeption of pitching moments and g-out compression caused by cornering, which alters your geometry and introduces greater dynamic input laterally into your tyres. If you were just riding around in a circle (say down some big spiral thing) at a constant speed in a constant position then yeah all bikes would be the same, but that's not at all analogous to a dh course.

Bikes that follow the ground well often have good grip in a vehicular sense, but the fact is that the rider is a far bigger component of the suspension/mass on a mountain bike than any other suspended vehicle, and we need good feedback to be able to make use of that grip. The problem with overly soft bikes (which do tend to follow the terrain very well, like V10s) is that you don't get that feedback to the same degree that you do with stiffer setups (to an extent). Predictability and geometric stability are, in my opinion, hugely important to the rider's sense of grip. Generally speaking, stiffer setups (or those with more damping) mean that the bike dives/rakes out less, and this means that you are able to achieve (or get closer to) dynamic stability in a corner quicker than you are with a softer setup. The sooner the bike's geometry stabilises (or if its movement is slower) the easier it is to feel when it's going to break loose. Again, if the suspension does anything sudden or especially variable through its stroke, you lose some of that predictability.

All that has to be balanced against bump absorption (incl axle path) and chassis stiffness, and a bike that is stable AND able to track the ground with the minimum necessary change in normal reaction force (which may be "low" if it's only 1000%!) will give you very good grip in corners.

 

[dhkid]

banshee, i have riden many v10s. but not mine, although the one which i have done runs on has a rider of similar weight. of course thats not the best way to comment on it, i found that it rode very similar to a vp, which i owned at the time. and it wasn't that i had problems with traction or anything, its just that the bikes that i said grip well are at a whole new level.... i had to get used to my new bike coz of that, i have had similar comments from a my mate who went from a dhr to a sunday...

sandwich, its agreed that bikes with faster rebound will track better... i get it what you mean by how the chain torque come in now, but then again most high pivot designs have pullies. but i get what you mean...

socket(tffm), i agree that the perfect situation in cornering doesn't work in real life, i was just building up my argument.


so, are they any comment from other ppl who feel the opposite to what i have felt on testing these two different suspension designs? i am a bit boggeled since a bike that i think doesn't grip as well when compared to other designs has been mentioned twice to have good corering grip....:huh:

when talking to ppl who ride those bike, they would comment on how it eats bumps and pedals through anything, but never how well it grips, with those bikes that i think grip well, other owners of these bikes have agreed how noticable the change was....

edit:forgot to add that maybe the siffer suspension designs get better grip just for the simple reason that you can pump them better? but i dont think thats the whole case tho, since they still grip as well on long high speed corners.

 

[Whoops]

Here's a question.
How often do you crash because you ran out of grip?

For me, the answers is... almost never. I crash because I run into a tree, or get bucked off by a rock I didn't see, or something else that doesn't involve lowsiding the bike (under or over steer).

To me this says that 'grip' isn't really the issue most of the time...

 

[dhkid]

but with more grip, you would be able to corner faster,tighter and avoid those trees and rocks...

whatever, i am not going to debate on how dh races are won, i just wanna know more about how rear sus works.

 

[Udi]

I think there was a fair bit of useful information right here that you should try to read and understand if you didn't already.. somehow I don't think you did?

Bikes that follow the ground well often have good grip in a vehicular sense, but the fact is that the rider is a far bigger component of the suspension/mass on a mountain bike than any other suspended vehicle, and we need good feedback to be able to make use of that grip. The problem with overly soft bikes (which do tend to follow the terrain very well, like V10s) is that you don't get that feedback to the same degree that you do with stiffer setups (to an extent). Predictability and geometric stability are, in my opinion, hugely important to the rider's sense of grip. Generally speaking, stiffer setups (or those with more damping) mean that the bike dives/rakes out less, and this means that you are able to achieve (or get closer to) dynamic stability in a corner quicker than you are with a softer setup. The sooner the bike's geometry stabilises (or if its movement is slower) the easier it is to feel when it's going to break loose. Again, if the suspension does anything sudden or especially variable through its stroke, you lose some of that predictability.

All that has to be balanced against bump absorption (incl axle path) and chassis stiffness, and a bike that is stable AND able to track the ground with the minimum necessary change in normal reaction force (which may be "low" if it's only 1000%!) will give you very good grip in corners.

 

[LaharDesign]

If you want a really good book on the dynamics of two wheeled vehicles read "Motorcycle Handlig and Chassis Design- The Art and Science" by Tony Foale. I've read this book cover to cover and it's probably the best book of its kind. His suspension analysis software looks pretty neat too.
http://www.tonyfoale.com/

I second your advice. That books like the bible of two wheeled performance chassis design and was one of my inspirations when drawing my first gearbox designs in the early 90's.

Sprung to unsprung weight ratio is the biggest influence on traction. Even on tarseal racetracks a 5% improvement is considered a race winning traction advantage. The lighter the mainframe of the bike the more its kicked upwards as the suspension compresses. As the suspension rebounds the heavier the wheel is relative to the mainframe, the more the mainframe rebounds upwards rather than the wheel rebounding down.
Too much compression damping - like platform systems- causes more upward energy transfered to the main frame, to little for the mass of the wheel will cause it to continue upwards past the top of the bump.
Too much rebound damping stops the wheel getting back on the ground after the bump, too little for the mass of the wheel will cause the wheels downward inertia to compress the tire like a spring and bounce the wheel off the ground.
With a gearbox configuration you can run much faster compression and rebound due to these effects and issues with rebound bucking are eliminated by the combination of high pivots and gearbox mass distribution. eg/ Lahar pros run fox dhx5.0 with propedal (initial compression damping) turned off hard against the stop and no more than 1 or two clicks of rebound. This doesn't feel at all "dead" but highly responsive as the natural frequency is very fast, enhancing the riders inputs.
more rearward wheelpaths give allow the suspension to deal with large bumps over a much longer elapsed time and with less wheelspeed, getting a lot more out of what you have. more vertical wheelpaths should have a small advantage in traction on smoother surfaces due to less distance travelled on rebound but this appears compromised by weight distribution shifting rearward.
Suspension enhances traction even on smooth surfaces because the breakaway and hookup dynamics are much gentler.
rally cars get max traction in a drift from the mass of gravel and dirt that is scooped up and packed against the outside of the tyres. I'm don't think this effect is common in bikes though.

 

[spacemanspiff06]

=>so i have come to the conclution that rear suspension that are firmer in the beggening of the stroke when compared to bikes which are very supple in the begining stroke will grip better.

i come to that conclution from when the suspension hits a bump, (assuming constant rebound damping on all the bikes shox) the firmer suspension designs will rebound as a faster speed because it is stiffer and given the rate is higher then the supple design and a constant rebound damping, it would rebound faster. so when a bike goes through a non perfectly smooth surface, the bike with the faster effective rebound will apply a greater total reaction force to the ground.

when a firmer and a softer suspension hit the same bump, they both recive the same amount of force and give the same amount of force back to the ground, the softer one just uses more travel and takes a little more time to give that force back. true the firmer one will give you more traction but it does it for less time. in a real world situation, the softer one with give more useable traction.

 

[dhkid]

lahardesign, wouldn't you have to account that the rider has some effect on the main frame too? and in that case the weight of the rear wheel is much lower then the combined mass of the main frame and whatever effect the rider has on it? but i get what you mean by a lighter rear wheel and rear triangle will grip better as it will react to the ground better.

udi, i read through it agian. so grip in corners is a combination how the rear sus reacts to the ground and how well it keeps the bike and rider in a position for cornering? hence giving an explanation of why softer set ups give the impression of less grip??

 

[ChrisKring]

I disagree. For a sinusoidal input at a constant speed blah blah, assuming you have a linear damper constant (which no shocks do) that might be the case, but what is considered "underdamped" for a rider's mass will invariably follow rough terrain the best. Underdamping will not "take the wheel off the ground" unless it's REALLY extreme given the spring rate to mass ratio (ie you're running bugger all sag and are topping out harshly), but overdamping most certainly will if the wheel can't follow the ground properly. For something like braking bumps (similar size/spacing hits) then yes there is arguably a critical point at which the suspension will be able to follow the terrain the best (where its resonant frequency is the same as that of the braking bumps) but otherwise I would most definitely err on the side of underdamping rather than overdamping.

I agree with what you are saying. However, I answered his ultra hypothetical question with the assumption of an equally hypothetical sine wave input.

I personally have always run underdamped set ups that are much faster than most people like. It works great in a straight line. However, in an off camber loose corner is where you need a little more rebound damping to prevent the rear wheel from drifting out. As I have gotten faster and have more experience on tuning the MX bike suspension, I have started to dial in more rebound damping and tend to run the front stiffer to keep the chassis level.

 

[Honus]

lahardesign, wouldn't you have to account that the rider has some effect on the main frame too? and in that case the weight of the rear wheel is much lower then the combined mass of the main frame and whatever effect the rider has on it? but i get what you mean by a lighter rear wheel and rear triangle will grip better as it will react to the ground better.

udi, i read through it agian. so grip in corners is a combination how the rear sus reacts to the ground and how well it keeps the bike and rider in a position for cornering? hence giving an explanation of why softer set ups give the impression of less grip??

Bingo! The rider's mass is so much greater than that of the bike that it has to be factored into how the bike will react when the rider's CG is shifted- especially during accelerating and braking forces. All things being equal, the less the unsprung mass the better the suspension will work. Damping rates are probably ultimately something that is realised through development and testing. It is interesting that Lahar brings up the topic of frequency as that's a pretty big deal in racecar damper design. I was just reading an issue of RaceCar Engineering where there was an article about Koni's latest develpoments with what they call frequency selective damping.......

When designing a suspension system you have to look at the big picture- how it all works as a system. Then you prioritize what is most important to you and try to figure out the packaging of the system to achieve your goals.

A few other decent books are "Competition Car Suspension" by Allan Staniforth and "Motorcycle Chassis: Tuning" by John Robertson.

 

[LaharDesign]

lahardesign, wouldn't you have to account that the rider has some effect on the main frame too? and in that case the weight of the rear wheel is much lower then the combined mass of the main frame and whatever effect the rider has on it? but i get what you mean by a lighter rear wheel and rear triangle will grip better as it will react to the ground better.

udi, i read through it agian. so grip in corners is a combination how the rear sus reacts to the ground and how well it keeps the bike and rider in a position for cornering? hence giving an explanation of why softer set ups give the impression of less grip??

Bikes are indeed a complex system with the rider the sprung weight and the whole bike the swingarm of a secondary suspension system. your legs are the spring and damper when standing, your ass a shorttravel elastomer when seated.
How much the riders weight can contribute to sprung mass of the primary suspension is dependant on frequency, but at the speed required to keep the wheel evenly weighted on choppy ground the sack of jelly that is a human being has little effect. Every person or company that has built a gearbox configuration know that the increases in traction are remarkable and obvious to every rider or spectator. The first national champion (junior dh and ds) to ride the Lahar mk1 proto in 1997 tried all the way down a 600ft switchback hill to break the rear-ends traction and came back raving about how everything he tried failed to do this. (this was with a position sensitive homemade damper that had very fatst response in the beginning of travel). Lahars have won mud races without losing traction once on the course while every other bike slid out every 2-3 seconds. There have been a number of 30 sec win in 3 minute mud races and one 50 sec one. 12 national champions have been involved in racetesting lahars and every one of them and dozens of other pro racers have found the traction enhancements of textbook chassis design to be overwhelmingly obvious. I'm afraid that anyone that now resists the results that me and dozens of other performance bike designers have found from basicly working with the Law of conservation of momentum is just looking for an excuse to no shell out on a gearbox bike. So build one yourself. I'll sell you a rohloff with all the mounting plates and chaingear. I'll call it the L-Box (for L-Men, the G-Whizzers can use the G-boxx).

suspension that rapidly stiffens as it goes through travel doesn't answer the max traction requirement of keeping the tire as evenly weighted on the ground as possible. It weights it too much on bumps and too little on hollows. Ideally the springs restoring force wouldn't change and some fancy computers would work out the required ride height and achieve it through dynamic damper adjustment. I hope we never go there!

 

[big-ted]

when a firmer and a softer suspension hit the same bump, they both recive the same amount of force and give the same amount of force back to the ground, the softer one just uses more travel and takes a little more time to give that force back. true the firmer one will give you more traction but it does it for less time. in a real world situation, the softer one with give more useable traction.

You're getting confused between the terms "force" and "impulse".

 

[Whoops]

Aaron = nail+hammer+head.

Spot on.

 

[LaharDesign]

Aaron = nail+hammer+head.

Spot on.

Cheers whoops

Further to the "rider is sprung weight " debate:
On a conventional bike that has chain extension under compression where the rider is standing:
-the only part of the riders body at all rigidly connected to the bike is his feet and lower leg. As lashback through the pedal is the result of suspension actuation, this mass must be accelerated to activate the suspension.
Therefore the riders mass that is involved in the primary suspension system is unsprung not sprung weight!