Hello, and welcome to Simplified on PowerDrift where we take complicated automotive ideas
and break them down into something simple that you can digest easily.
Today we're starting a four part series on motorcycle suspension, that's right, it's
something that you've asked for consistently.
So before we go ahead, subscribe, bell notification icon, thumbs up and share this video with
your friends because I know this one will help.
So, the biggest misconception about suspension is that it exists to make you comfortable
on the motorcycle, that's not actually what it does.
If you go back to motorcycles, as they began, they used to be called bone shakers and the
reason for that is because they had no suspension.
So you had very, very few paved roads, if at all, and you had motorcycles that had no
suspension, so essentially, when you went over a bump, everything would shake like this
and that's why they were called bone shakers.
So in time we added suspension and yes, it did make the process of riding motorcycles
more comfortable and today's sophisticated suspension is an absolute joy to use, an unsophisticated
crude suspension, honestly, you know that it's doing a job, but it's not doing an amazing
job and why is that?
Suspension's job primarily is to ensure that your tyres are in firm, secure contact with
the ground, nothing more, nothing less and the reason why this is important, is because
if your tyres aren't touching the ground, then you suddenly lose your ability to accelerate,
to brake and to turn the motorcycle while the tyres are in the air.
Now, why would a tyre lift off into the air at all?
Think about a motorcycle from the bone shaker days, which has absolutely no suspension at
all, and is hitting a bump that shaped like this and you hit a lot of bumps that are shaped
like this, whether the peaks are tall, the peaks are shallow, in all cases, when the
motorcycle has momentum, momentum will tend to carry the motorcycle upward and that means
that your tyre will leave the ground, even if for a moment and if in that moment, you
try to turn the handlebar, hit the brakes or open the accelerator, as long as the wheels
aren't in contact with the ground, the motorcycle doesn't really react.
If you look at the suspension units on your motorcycle, whether front or rear, they're
essentially composed of two components, the spring and the damper.
Now we all know what springs do, right?
They're the things that go sproing-sproing and they look like a coiled metal, right?
The damper's job is to stop the sproing-sproing from being uncontrolled, so that you can predict
how that spring is going to work and that's literally all that damping does, right?
The properties that we're going to talk about in other videos, they'll follow very, very
close to this one, are compression, rebound and preload, the three properties that you
need to worry about when you talk about motorcycle suspension.
In sum compression is the easiest to understand, so let's have a wheel here and you've got
a suspension unit on top.
When it hits a bump, the wheel rises, when it rises, it compresses the spring and the
rate at which the spring compresses effectively is the compression-damping of the motorcycle.
Now, obviously, you can have quite a bit of variation here.
So if you look at the Royal Enfield GT Cup race bikes, they have linear springs, which
means that the rate of the spring which is the distance between each of the windings
is the same from the bottom of the spring to the top of the spring.
But most street motorcycles will use something called progressive damping, which means that
the bottom of the spring, it will be quite soft at the top of the spring, the spring
rate will be dramatically different, it'll be quite hard and the reason you do that is because
a racer who's racing will actually never use the softest part of the spring, they usually
load the motorcycle up quite a bit
so they run linear springs, whereas street riders generally put a lot less load on the
suspension and therefore having variable rates, whether it's two rates, whether it's actually
variable rates has an advantage, because you can get quite a soft feeling at the bottom
and a much firmer spring on the top so that if you land from a big jump or something,
you don't immediately bottom the suspension out.
The damper inside is basically a hydraulic unit, which moves much slower than the spring.
So when this tyre is moving up, and it's compressing the spring, it's also putting pressure into
the damper.
The damper's job is to stop the spring from collapsing completely and more importantly,
to control how the spring will return to its actual shape.
If you have a ballpoint pen at home, and you take the spring out, and if you compress it
and just leave it you'll see that the spring sort of bounces around, it's this bouncing
around that the damping will control and that part, since it's expanding, again, is called
rebound damping and that's the second term that we need to know about suspension.
So just to summarise what we've said so far, suspensions job primarily is to keep your
wheels on the ground and bumps make this challenging because if the road falls away from the suspension,
the tyre has to be able to expand into the gap and keep contact and if the road bumps
upwards, then as it comes off the crest, it has to be able to absorb the climb up to the
crest and the expansion after the crest, both, which is why when you sit down on your motorcycle
and it compresses a little bit, what you're doing is taking up some of the travel with
your weight and when you start moving, opening the throttle or closing the throttle, you're
moving through the stroke of the suspension.
The important thing to know is that all the parts of the suspension movement, the entire
stroke as we call it, the bottom, the top and the middle are not as good as each other
and therefore all suspension units have what we call a sweet spot.
The way we ensure that the motorcycle rides in the sweet spot as long and as often as
possible is preload adjustment and what it does essentially, is it changes how much of
the spring is compressed by our weight, so if you're heavy, you want the spring to compress
quite a bit less than stock, so you set the preload higher and if you're lighter, you
set the preload to the least and the idea of that is that the spring stays extended
as much as possible, so when it is loaded up, you're working with the sweetest part
of the suspension.
A lot of people think preload will make your suspension firmer or softer and that's not
actually the case, although it can feel like that.
What preload actually changes is the ride height of the motorcycle once your weight
is on it.
To get an example of this, just to see how this thing works, if you take your motorcycle,
put it on the side stand and just lift the front wheel off the ground, you'll immediately
see that the front shock extends, that's called the free length of the suspension or the fully
extended length of the suspension.
As soon as you put the motorcycle back on the ground, it compresses a little bit and
if you sit on it, it compresses further.
Preload essentially controls how much this compression is and you can use preload clickers
to try and set it to the exact height where you will feel the best.
The way we do that is called setting sag, and we'll cover that in another video.
But if you have a motorcycle that has preload adjustment, even if just at the rear, it is
super important that you set your sag and when you add a pillion or a substantial amount
of luggage, you will find a far far superior motorcycle if you were to play with the preload
and just set it to a firmer setting because now obviously you've loaded the motorcycle more.
If you do it right, the difference in feel from having a pillion onboard and you riding
alone should be absolutely minimal.
So why is suspension important?
Suspension is important because it not only controls your comfort, it is a great side
effect to have, it actually determines how much you can control the motorcycle because
the better the suspension is, the better the setup is, the your more wheels stay on the ground,
the more they stay on the ground, the more controllable, predictable and confident the
motorcycle will feel, the more confident you feel, the faster you will go and in that sense
to me the two biggest upgrades you can make to the motorcycle is, one, your fitness and
skill and right after that comes suspension, it's not the ECU, it's not the exhaust and
it's certainly not the underlighter kit that you've been eyeing.
Thank you so much for watching.
This is a very quick episode on suspension on PowerDrift on Simplified, where we take
complicated ideas and break them down into small bite sized pieces that you can digest easily.
This is part one of four, so stay tuned, hit the bell notification icon because when we
talk about compression damping, preload and rebound damping in their own we discuss that
in detail, you don't miss out.
Thank you so much for watching.
If you'd like to discuss this further, leave us a comment, if there's other topics that
you think Simplified should attack, leave us a comment as well.