Ijaw Dictionary Online

How Automobiles Work

Motorcycle suspension. All motorcycles have suspension system. But how do they work? Why are there different settings for different
applications? And how do you set it up? Lets figure this stuff out. So the goals with a motorcycle suspension
system are the following: We want: Maximum traction,
Traction ‘feel’, Controlled pitch,
minimal harshness, Controlled bottoming,
And consistency (not fade) So for starters, what is this so called maximum
traction?This all starts with the tires Rubber generates friction in three major ways:
a) Adhesion, b) Deformation, and c) Wear. (This and more more information on tire traction
can be found in: “The Racing & High-Performance Tire, Paul Haney, 2004”, link to it down
in the description) a) Adhesion
Adhesion is a property of rubber that causes it to stick to other materials, like tape. If the two surfaces were perfectly smooth
the true area of contact would be the same as the observed area of contact, but this
is not the case. Real surfaces are actually very rough, so
contact is limited to the highest protuberances on each of the two surfaces. http://insideracingtechnology.com/Resources/vertload.gif
As you can see in Fig. 3.3, larger loads on the rubber presses the road irregularities
into the rubber, increasing the contact area. More area in contact means more adhesion between
the surfaces and higher friction forces. This situation satisfies the general requirements
of the friction equation, Ff=Cf x Fv. b) Deformation: Mechanical Keying
Rubber in contact with a smooth surface generates friction forces mainly by adhesion. When rubber is in contact with a rough surface,
deformation comes into play. Movement of a rubber slider on a rough surface
results in the deformation of the rubber by high points on the surface called irregularities
or asperities. A load on the rubber slider causes the asperities
to penetrate the rubber and the rubber drapes over the asperities. The energy needed to move the asperities in
the rubber comes from the differential pressure across the asperities as shown in Fig. 3.4,
where a rubber slider moves on an irregular surface at speed V.
http://insideracingtechnology.com/Resources/mechkey.gif c) Wear
In addition to adhesive friction and deformation friction, rubber produces traction forces
by means of tearing and wear. As deformation forces and sliding speeds go
up, local stress can exceed the tensile strength of the rubber, especially at an increase in
local stress near the point of a sharp irregularity. High local stress can deform the internal
structure of the rubber past the point of elastic recovery. When polymer bonds and crosslinks are stressed
to failure the material can’t recover completely, and this can cause tearing. Tearing absorbs energy, resulting in additional
friction forces in the contact surface. Wear is the ultimate result of tearing. When local stresses increase in strength past
initial tearing or remain at high strength for a period of time, that tearing can result
in separation of material. Total Friction
Now we can write a more general equation for rubber friction:
Ftotal=Fad(hesive) + Fdef(formation) + Fwear 2. The maximum lateral force that can be developed
increases as the vertical load increases, as shown in segment 1. BUT because of tire load sensitivity https://en.wikipedia.org/wiki/Tire_load_sensitivity,
it is at a diminishing rate. So for a pneumatic tire the coefficient of
friction decreases as the vertical load increases. So, in order for the tires of a motorcycle
to provide maximum traction, they should: – Be in contact with the ground
– Not bounce or oscillate – Be loaded up appropriately
But what does the suspension have to do with this?Lets have a look at a motorcycle without
any suspension except its tires. Our inappropriately designed bike goes over
a simple bump and what happens? The front and rear tires loose contact with
the ground at the back of the bump, because the tires do not have enough travel to soak
up the bump. When the tires regain contact with the ground,
the motorcycle oscillates, bouncing up and down. So in other words, this bike will:
– Lose traction over bumps – Have an uncontrolled pitch, because of the
unwanted oscillation going over bumps – Be very harsh Lets try to fix this situation by introducing
a spring between the wheels and motorcycle. We now have what is called a sprung mass,
which is the mass above the spring, and unsprung mass, which is the wheel and other components
going up and down together with the wheel, such as brake disks, calipers etc. Ideally, we want the load between the tire
and ground to remain constant going over the bump. We also want the sprung mass to move in a
straight line. So, what happens if we ride this motorcycle
with only a spring between the wheels and the sprung mass over the same bump as before? It does better than the bike without any suspension. The amount of time in the air at the back
of the bump is lessened and the ride looks slightly smoother.However, we still see oscillation
after the bump, causing loss of traction. So how can we fix this? Lets add a damper between the sprung and unsprung
mass as well. The sprung mass follows an almost horizontal
line and the unsprung mass is in contact with the ground throughout the scenario, except
for a very small bit at the back of the bump.We can also see that the bike does not oscillate
after having hit the bump. So, this is a simplified version of how the
suspension works on most motorcycles. Some motorcycles, such as the Ducati Multistrada,
BMW HP4 or Yamaha R1M have what is called semi-active suspension systems. This is not to be confused with fully active
suspension systems. These semi-active systems work by attaching
small servo motors to the fork and shock adjusters, the servomotors alter the damping and preload
depending on the conditions, a mode that the rider has selected or a combination of the
two. Thus the settings of the suspension system
can be optimized ‘on-the-fly’, depending on the environment the rider is in. Which practically means that the unsprung
mass keeps in contact with the ground better, simply because the suspension settings match
the environment. A fully active suspension system replace the
spring and damper with hydraulic or electromagnetic rams, which then actively control the wheels
position. A perfectly functioning active suspension
system would maintain perfect traction over bumps, because the wheel would be pulled up
at the face of the bump, and pushed down on the back of it. Thus the terminology, active suspension; it
is actively moving the unsprung mass up and down. ____ If you want to see more content like this
please subscribe to my channel and remember to press the bell notification button. Also, head on over to instagram and follow
me there, my profile is called mike on bikes official, link down in the description. —— Ok, so we understand the fundamentals of tire
traction, and of a spring and damper suspension system. Now we need to understand some basic motorcycle
geometry. You may have noticed some fundamental flaws
with the simplified motorcycle design shown earlier. Namely that the front end doesn’t have any
rake angle, which means that this motorcycle would be extremely unstable. So unstable that it would be hard to ride
it even at bicycle speeds. So the rake angle is the angle between the
steering axis with respect to a vertical line. The wheel + tire has a certain diameter, and
from these measures we derive a very important measure, called trail. Trail is a measurement of how far the contact
patch of the front tire is behind the point where the steering axis hits the ground. You get the number by extending an imaginary
line through the steering axis to the ground, then you draw a perpendicular line through
the front axle to the ground. So why is trail so important? Well trail is what makes it possible to stay
balanced on two wheels, because it forces the front end to stray straight when the motorcycle
is driven forward. So the further the wheel is behind the steering
axis, the more stable the bike is and vice versa. So less trail equals quicker steering bike,
but also a more unstable bike. The effect is obvious if you have seen a motorcycle
going down the track in a straight line when the rider fell off. The bike wants to go in a straight line because
of trail. The amount of trail you have can be adjusted
by: – Changing the triple clamp offset, longer
offset=more trail and vice versa – Moving the fork tubes in the triple clamps,
moving them upwards will result in less trail and vice versa
– Changing the front wheel diameter, a larger wheel will provide more trail and vice versa,
this is why most supermotos and a lot of race bikes are outfitted with 16 and 16.5 inch
front wheels, instead of 17 inch, to provide less trail and faster turn in. I should mention that 16 and 16.5 inch wheels
are also fitted on these bikes because the tires sidewall height as well as profile enable
a bigger contact patch at deeper lean angles. – Adjusting the fork bottoms to move the axle
back or forward. Moving the axle forward will result in more
trail and vice versa. – Lastly you can adjust the ride height in
the rear. Lowering it will increase the rake, which
provides more trail. Ok cool, so lets add some rake angle to our
front end, and also some brakes, I mean it would be good to be able to brake before hitting
the corners right? Lets also assume that this is an upside down
fork, as seen on most modern motorcycles. Now, what will happen if we apply the front
brake with our front fork at an angle like this? First of all, the front forks will compress,
this will cause the wheelbase to decrease, simply because the forks are moving at an
angle. So the wheelbase is the distance between the
front and rear axles. A bike with a short wheelbase will transition
side to side and turn in quickly, but has the downside of being unstable. A bike with a long wheelbase will transition
slowly, but will be more stable. Tony Foale gives three main reasons for this:
1. For a given bend a long wheelbase motorcycle
needs the front wheel to be turned farther into the bend. 2. For a given sideways deflection, the angle
of the rear wheel to the direction of travel is smaller with a longer wheelbase, thus providing
greater directional stability 3. A longer wheelbase bike sees less load transfer
forward under braking, and less rear when accelerating. Also the moments of inertia in the yaw and
pitch planes are increased, which makes longer wheelbase motorcycles more sluggish and stable So braking with an upside down or conventional
fork will have the effect of deceasing the wheelbase of the bike, making it unstable,
but easier to steer. Secondly, as the forks compress they run out
of travel and thus their ability to travel over bumps decrease as the fork tubes bind
and static friction takes over. This effect is called brake dive, and is a
very important attribute that one must consider when designing a suspension system. Some older viewers might be thinking to themselves:
Wait a minute now, didn’t engineers solve the problems with brake dive a really long
time ago? Like with for instance the Earles fork, and
later the Saxon-Mododd and Hossack forks, marketed as Telelever and Duolever respectively
by BMW. So the earles fork is a variety of what is
called a leading link fork, which suspends the wheel on one or several links with a pivot
point aft of the wheel axle. It was invented by English engineer Ernest
Earles in the early 1950s. When the front brakes are applied on a motorcycle
with this type of fork, the suspension extends, providing more travel. Another feature with this front end is that
the wheelbase is not changed much at all, even with a lot of travel. The earles fork had so many theoretical advantages
that BMW decided to ditch the telescopic forks on all their bikes in the 1950s to use the
earles one instead. Now we should remember that BMW invented the
hydraulic telescopic fork in 1935, the forefather of modern cartilage forks. What are the downsides with the earles fork
then? Well for starters it is a heavy solution,
secondly, forks like the telescopic and earles ones have a large mechanical advantage over
the steering head. In order to minimize frame twist you have
to brace the steering head. Or in simpler terms, make the frame of the
motorcycle really beefy, which makes the motorcycle top heavy. So any other disadvantages with the Earles
Forks? Lets think back to the goals with an ultimate
suspension system: We want:
Maximum traction, Traction ‘feel’, Controlled pitch, minimal harshness, Controlled bottoming,
consistency (not fade) While Earles Forks are theoretically good
at almost everything, they lack in Traction ‘feel’. First of all, having the front end rise when
braking is counterintuitive, so it is something that a rider would have to spend a long time
getting used to. Secondly, with added pivot points comes added
play in the system. This removes feel of front wheel traction. Think about it, which motorcycles provide
the best feel for front wheel traction? Sportbikes with clip-ons. The clip-ons are mounted directly to the forks
and the rider leans over the front end. So while you could theoretically brake harder
with an earles fork, because the fork provides more travel, the rider wouldn’t have much
feel for front wheel traction, which is of course very important when being on the brakes
going into a turn. Another aspect to think about is that while
changing the wheelbase will make the bike more unstable, it makes it easier to steer
to steer in. Isn’t this actually something desirable? I would argue that with the current riding
styles in Sportbike racing it is desirable to have the wheelbase slightly decrease when
entering corners. What about the Saxon-motodd, aka Telelever,
or the Hossack, aka Duolever forks? They suffer from similar shortcomings as the
Earles does. And it is the same with Hub centre steering. So, have there ever been any race winning
bikes with a front end other than telescopic forks? Of course. The 1990s Britten V1000, designed and built
from first principles by John Britten and his team in New Zealand had a Hossack front
end. They were successful at the Isle of Man, Daytona
winning Battle of the twins in 1994. Unfortunately Britten passed away in 95 from
skin cancer, so the development of the v1000 stopped. Another example of successful bikes with leading
link forks is this 125cc Honda factory motocrosser from 1980. Which was originally designed by Valentino
Ribi. Yasuo Tofukuji won the 1981 All Japan 125
CC Motorcross championship with that bike. So did all other manufactures all of a sudden
adopt that front end after that? Nope. Because not only are the advantages over telescopic
forks very slight, adopting a new front end would also require a significant amount of
testing and development. This is something crucial to understand about
a suspension system, they require significant amounts of testing to perform well. For now, telescopic forks still provide the
best balance of tuneability, traction feel, mass and simplicity for most consumer motorcycles
and race bikes. ________________ If you want an even more in depth explanation
of everything I am covering in this video, here are some great books to get you started. ________________ So we talked about braking, now what about
accelerating? Well if we are going to talk about accelerating,
we need to understand the rear end a bit better. Lets look back at the simplified motorcycle
design shown earlier. Lets assume it has a chain drive. When you roll the throttle, our simplified
motorcycle will squat, or pitch rearward. What does this do to our suspension travel? It diminishes our travel. To solve this problem we need to introduce
anti-squat, or in other words, we need to stop the rear suspension from compressing
under acceleration. On a motorcycle with a chain, there are two
primary ways to achieve anti-squat. One is to put the swing-arm at an angle. Lets have a look at the rear end of a modern
motorcycle. Look at where the swingarm is connected, this
is called the swingarm pivot point, now look at the rear axle. Draw a line though the pivot point and the
rear axle, then imagine a horizontal plane that goes through the pivot point. The angle between the plane and the line is
the swingarm angle. Imagine what happens if the rear wheel is
driving the bike forward, because of the upwards angle of the swingarm, the suspension is extended. The second force enabling anti-squat comes
from the chain pulling on the axle in a direction parallel to the top chain run, which will
extend the rear suspension. The amount of anti-squat you gain from chain
pull can be altered with sprocket sizes. A smaller front sprocket will provide more
anti-squat, and a larger rear will provide some, but not as much, anti-squat effect and
vice versa. On a MotoGP bike, the swingarm pivot point
and rear axle position can be altered quite significantly. So thus they can change the swingarm angle
a lot For most of us though, we can’t change the location of the swing arm pivot point. So now you might be asking yourself; how much
anti-squat do you want? The so called ‘amount of anti-squat’ is
easiest explained as a percentage that indicate how much weight transfer is offset by anti-squat. If you have for instance 60% anti squat, its
effect offsets 60 percent of the weight transfer on acceleration, and thus the suspension would
still compress. At 100% anti squat, the suspension would not
move due to weight transfer. How much you want depends on a lot of factors,
and the books I mentioned previously all provide slightly different answers. I have also found many articles in Motorcycle
magazines talking about this. Their answer is always slightly different
as well. At the end of the day, the answer for road
racing machines lies around 100% at corner exit, important to note that corner exit isn’t
some neutral state, but rather the real world case where the throttle will be applied and
maximum grip on front and rear wheels is desired. We must remember that the rear wheel moves
in an arc when the suspension compresses and extends. This alters the swingarm angle and thus the
forces generated. If the rear end squats too much, you will
lose traction on the front tire because of load transfer, causing the bike to understeer. If you are experiencing this on your motorcycle,
you need more anti-squat. If you have too much anti-squat, the Center
of gravity will move upwards, which will pull the tire away from the ground, resulting in
loss of traction, or in other words the bike will oversteer dramatically. One theory proposed in Race Tech’s motorcycle
suspension bible is that anti-squat percentages slightly above 100% provides a momentary push
against the ground, which will increase traction. Others propose that percentages slightly below
100% are the best. I think you get the gist of it, it all depends
on the bike, the rider, the track and the conditions. If your bike is understeering, increase anti-squat
if it oversteer dramatically, try decreasing anti-squat. Anti-squat of course isn’t the only cause
for over/understeer, but it is a significant part of the puzzle on modern 200+ Horsepower
machines. On a dirt bike having the ability to extend
the rear suspension with the throttle has some benefits. One being that large jumps can be cleared
by getting lift on the take offs and another being landing jumps being on the throttle. To achieve this the anti-squat has to be 100%
or greater. The books I recommended earlier provide methods
to measure the anti-squat percentage with the bike in a neutral state using various
methods. If you want to adjust anti squat you can do
this by: – Changing sprocket sizes front/rear, which
changes the chain pull, A smaller front sprocket will provide more anti-squat, and a larger
rear will provide some, but not as much, anti-squat effect and vice versa. – Adjusting the ride height on the rear suspension,
which changes the swingarm angle, taller ride height=more anti-squat and vice versa
– Moving the front forks in the triple clamps, which changes the swingarm angle, as well
as trail. Moving the forks tubes up will decrease anti-squat
and vice versa – Moving the swing arm pivot point, (not possible
on most consumer available bikes) – Shortening the swingarm length by moving
the rear wheel and shortening the chain, which will provide less anti-squat and vice versa Remember I mentioned that we assumed that
this motorcycle had a chain. What about shaft drive? With a shaft transmission the wheel driving
torque produces an opposite torque on the crown wheel housing that rotates the swingarm
backwards, which lifts the rear of the machine. Most shaft driven motorcycles have a large
anti-squat percentage and thus do not perform well on a race track. Solutions have been developed to counter this
which involve using a torque reaction link. However these are not really that interesting
for race bikes, because of the added mass and complexity. What about the way the shock attaches to the
swingarm? This is very important indeed. Most modern motorcycles utilize what is called
rocker arm and linkage suspension with a single shock. This enables progressively stiffer resistance
to wheel deflection using a constant rate spring. Which combines sensitivity to small bumps
with an increasing check for larger ones. All the manufactures have slightly different
names for their specific systems, but they all work basically in the same way. There is not really a substitute to linkage
rear suspension for racing, as other solutions are inferior when it comes to the suspensions
performance. There are some rare cases that can be made
for hard Enduro bikes where mass is very important and speeds are low. There a simple swingarm can be used with a
progressive spring. What about how to distribute the weight on
the motorcycles front and rear, also called weight bias. Most sport bikes are setup to provide a 50/50
weight bias including the rider. But remember, the riders weight will affect
this. Dirt bikes usually have a weight bias towards
the rear, 45/55 with a standing rider, which again is affected by the riders weight and
position. Dirt bikes allow the rider to move around
significantly and thus the weight bias can be shifted easily. On sport bikes the weight bias can be altered
by moving the rear wheel fore/aft. Moving the wheel rearward will result in more
weight on the front wheel. Padding under the saddle can also help move
the rider forwards on the bike. ___________________ So now that we understand the basics of tire
traction, geometry as well as the front and rear end of motorcycles, It’s time to tackle springs and damping. (This information on springs, damping and
friction, and more can be found in: “Race Tech’s Motorcycle suspension bible, Paul
Thede and Lee parks, 2010”, link to it down in the description) As we talked about earlier, both your front
and rear suspension have springs, which have a certain spring rate. The spring rate is the stiffness of the spring,
commonly measured in N/mm or pounds/inch. These springs are setup from the factory with
a certain amount of pre-load, which means that the spring is compressed a small amount
from its free length. The spring rate and preload also affects something
very important, and that is the ride height as well as the suspension sag. Now you already know that the ride height
has an effect on the motorcycles geometry, which will alter the turn in as well as acceleration
phases of cornering. Suspension sag refers to how much the motorcycles
suspension compresses from fully extended with the rider on board. This compression is VERY important, because
it enables the suspension to extend down into dips and depressions in the road surface. Without suspension sag, the tire would lose
traction going over these dips. You might be thinking to yourself right now:
“ok ok, lets get to the compression and rebound damping. Isn’t that how you tune suspension?”. If you are thinking that, what you need to
understand is that if you don’t have the right spring rate and suspension sag, any
other settings to your bikes suspension doesn’t really matter that much. What you also need to understand then, is
that the spring rate which you need will vary depending on your weight and application. An easy way to check if you have the right
spring rate for your motorcycle is to measure your suspension sag and see if you can adjust
it to the range given by the owners manual. If there is too much sag in the suspension
and you run out of pre load adjustment range, you need a stiffer spring. Also, if you weigh over 82 kg, 180 pounds,
or 12.9 stone, you will most likely have to get stiffer springs, assuming you want a well
setup suspension system. There are primarily two types of springs: – Straight-rate
– Progressive Straight rate springs maintains a constant
rate throughout its travel. Progressive springs change their rate in relation
to where they are in their travel. There are many variations of progressive springs,
with true progressive, dual-rate, triple rate and so forth. Which type of spring you need will depend
on the application and personal preference. According to Race Tech’s Motorcycle suspension
bible, straight rate will be the best option for most bikes and applications. Progressive springs have the advantage of
providing controlled bottoming, which we talked about at the very beginning of the video. However, with a modern linkage rear end, bottoming
out is not a big issue. We should also remember that, telescopic forks
contain an air space , as the fork is compressed, the space gets smaller and the pressure increases. This affects the total spring force of the
forks in a progressive manner. Also, adding more oil in the fork tube will
decrease the air space and thus affect the total spring force. Straight-rate springs are also easier to work
with given their constant rate. _____________ I mentioned that you should measure your suspension
sag; how do you actually do this? There are several methods, which you can read
about in the books I mentioned. For the rear suspension: The short version is that you need to measure
the distance between the axle and a near vertical point on the frame with the suspension fully
extended and then with the rider sitting on the bike. To fully extend the rear suspension you need
to get the rear wheel in the air. With dirt bikes you can lift them on top of
a stand, with a touring bike you can get them on a center stand. Then the rider sits on the bike and the distance
is measured again. The difference between these two measures
is the static sag. You want roughly 25-35 mm of sag on a sport/street
bike, and 95-100 mm on a dirt bike. For most rear shocks you adjust adjust the
pre-load by using a C spanner hook wrench. Please see your owners manual on how to do
this on your specific motorcycle. Because of static friction, you may have to
push the bike down slightly and let it back up, and then lift it up and let it sit back
down, to get an accurate read of what your static sag is. Race tech’s motorcycle suspension bible
provides a great method of doing this. For the front suspension:
– Put a zip tie around the lower fork legs – Put the bike in a chock or have someone
hold the bike steady while you sit on it – Push the bike down slightly and let it settle
– Have your mate push the zip tie to the dust seal
– Now get off the bike and pull the bike up so that the front suspension fully extends
– Have your mate measure the distance between the zip tie and dust seal, that is your sag For a sport bike you want roughly 25-35 mm
of sag and on a dirt bike 60-75 mm. On most motorcycles you adjust adjust the
front fork pre-load with a wrench. They typically move independently of the fork
tube. Looking like this. More lines=less preload, fewer lines=more
preload. Please see your owners manual on how to do
this on your specific motorcycle. Lifting the bike up and letting back down,
and pushing it down and letting it go back up is a great way to check the health of your
suspension system by checking what is called the stiction zone. The stiction zone is the difference between
where the bike stops when being pushed down, let back up and lifted up and being let back
down. Suspension bible recommends having a stiction
zone of 20-40 mm for telescopic forks and no more than 6 mm for the rear suspension. If the stiction zone is bigger than this your
suspension system needs a service. __________________ Now lets get into damping; what is damping
really? Well damping slows down the movement of the
suspension. Compression damping slows down the suspension
as it compresses when going over bumps. Rebound damping slows down how fast the suspension
extends. I’m not kidding, its that simple. Damping in modern suspension components almost
always involve a fluid that is forced through a hole, or in more complex systems a bending
shim stack, where high and low speed compression and rebound can be tuned. The degree of damping is mostly determined
by flow rate. When you adjust the compression or rebound
on your suspension, what you are doing really, is adjusting the size of the hole that the
oil is forced through and thus the flow rate. The flow rate is also affected by the oil
viscosity, which is a measure of a fluids resistance to flow. A more viscous oil is more resistant to flow. So compression damping slows down the suspension
when going over bumps. The velocity of the compression is affected
by the size, shape and the speed at which you hit the bumps. Bumps with a slope causes slow suspension
movement, while bumps with a sharper edge causes fast movement. Thus the need for high speed and low speed
compression damping. Compression damping affects the traction,
traction ‘feel, plushness and bottoming resistance. So it is easy to understand that if you add
more compression damping, you get more bottoming resistance. It is also easy to understand that more compression
damping provides less plushness and thus causes a jarring ride. But what about traction and ‘traction feel’? Well actual traction is not that complicated. If you have too little compression damping,
going over a bump will cause the wheels to loose traction because they lift above the
crest and thus the tires are unloaded. If you have too much compression damping,
going over a bump will push the whole bike, or sprung mass, upwards, creating a harsh,
jarring ride. The wheel can also come off the ground and
skip over bumps, with excessive amounts of compression damping. Where do you adjust the compression? – On most bikes with up-side down forks you
adjust compression damping on the bottom of the forks, this can be counting turns from
a mark or clicker style, where you count the clicks
– On the rear shock the compression adjustment is usually located on top of the shock
– Most of of them have an indicator of +- as well as a short text saying Comp. – Please see your owners manual on how to
do this on your specific motorcycle. So how do you know what compression damping
you need? – Well the suspension should not bottom, you
can check this putting a zip tie around your lower fork legs on upside down forks. If the zip tie is pushed all the way down
you are bottoming out and probably need more compression damping. If more compression damping isn’t solving
the problem you need stiffer springs. – You also want a plush ride, which is usually
achieved by less compression damping – Maximum traction is found somewhere between
the forks not bottoming out and a really plush ride An easy way to test your compression damping
is to first adjust all your suspension settings to ‘standard’ which you will find in your
owner manual. Then, find a reasonably bumpy section of road. Ride over the same stretch a few times. If you have too much compression damping,
the ride will be very harsh and the front wheel will bounce over bumps. If it feels like the front suspension is bottoming
out on over bumps or during braking, you have too little compression damping. Again, you want a plush ride while not allowing
the suspension to bottom out. ———————— Now to rebound damping. So rebound damping slows down how fast the
suspension extends. Less rebound damping means the suspension
extends faster and more means it extends slower. When going over a bump, too little rebound
damping will cause the suspension to extend rapidly on the backside, causing the tire
to oscillate. Which results in loss of traction. Too much rebound damping means that the suspension
will not extend fast enough, which means the tire does not touch the backside of the bump
causing loss of traction. Also, too much rebound damping diminish the
available suspension travel by packing. Which can happen over a series of bumps, where
the suspension does not return to its original starting point. With each bump reducing the available travel. Less rebound damping generally provides a
more plush ride and adding rebound makes the ride more harsh. Testing rebound damping requires practice
and a lot of testing. One way is to do the so called push test. This is where you stand next to the motorcycle
and push down hard on the saddle. You then let your hand rest on the saddle
as the suspension rebounds up. You are observing how fast the suspension
extends and if it bounces at the top. If you have too much rebound the suspension
will extend slowly and settle on the top with no bouncing. If you have to little rebound the suspension
will extend rapidly and bounce several times on the top. Race tech’s suspension bible recommends
that a good amount of rebound damping will result in the suspension bouncing once and
settling down. Rebound damping can and should also be tested
by experimentation at the track or on a small stretch of road. Front fork rebound is usually adjusted on
the fork cap and rear shock rebound is usually located on the bottom of the shock. Please see your owners manual on how to do
this on your specific motorcycle. _____________________ I hope you have learned something from this
video and that this has sparked an interest in you for motorcycle dynamics and suspension. If you want to learn more and have a reference
to all this please check out the books I mentioned in the beginning of the video. Having these references available when you
are playing around with your suspension is really helpful. Get them books and get learning.

28 thoughts on “Motorcycle Suspension | EXPLAINED

  1. Motorcycle Suspension for Dummies.

    Very easy to understand. More videos of this type are welcome!

  2. I would love I video like this but on transmission!!! WHAT IS CHAIN TENSION!! why is it important… Why dont all race bikes use belts instead? Or shafts for that matter…

  3. Suspension was also the key reason behind Williams winning consecutive F1 World Championships in the 80s

  4. Add a wheelie bar that eliminates the spring and shock on the rear then cut the front fork springs to drop the front an appropriate drop. Rev the motor, drop the clutch, shift up to the mph limit. Repeat.

  5. I've got an idea based on a problem. What about the cases like myself, when you have a bike consider adjust to road and off road at the same time?? Trail bike in my case. I suppose that when you improve one way you lose in the other way. Because you know super moto maybe you can help

  6. Another amazing video, Mike! Suspension is such a broad topic and you managed to squeeze its basics into a relatively short video – that's a tremendous work!
    Having signal processing background (both digital and analogue) I was really happy that Tony Foale in his book described suspension as a frequency filter. So I would recommend that book as well

  7. Hi Mike.
    During the Husky 701 bounce-test in your Video……
    Your Rear-End, your Shock Rebound setting is much to slow, to much Rebound-Damping.
    Esspecially in Low-Speed Extension….on the top End of Extension.

    Also a good motorcycle Suspension Video:
    ….and on.

    Old but good!

  8. Man you've been a great help so far, I've been doing an internship on the rear suspension design and your all your vids basically summarized the 3 months worth of theory in less than an hour in total. Thanks for sharing!

  9. Mike will you make a video about the new Motogp Ducati system they use to actually squat down the rear coming out of corners? They call it holeshot device but they not only use it at the start but also coming out of corners by pressing a button on left handle bar

  10. Love the video. I can rebuild the engine but fear turning the suspension knobs because I don’t know what I’m doing.

Leave a Reply

Your email address will not be published. Required fields are marked *