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 and today, we're digesting a
topic that you have asked for at some point or the other almost from the time that Simplified started
here on this channel, we are talking about rev matching or blips shifting.
Both are techniques which we use when we are downshifting, when you're going down the gearbox
from fifth to fourth to third to second to first, then let's get right into it, but before we do,
you know what to do right? There's four buttons that you should really be hitting. So,
downshifting on a sequential transmission is a little bit complicated, because there is the
potential for causing damage to the transmission, which is why we do use clutchless upshifts a lot,
but we will never almost never use downshifts without the clutch. But when it comes to
downshifting, the problem is that the revs on the engine rise as you go down the gearbox for
the same speed and there you have a potential for disaster. This is because when your bike is
running smoothly, at let's say 50kmph in third gear, and you downshift to second for a moment,
the wheel is going faster than the engine, it's trying to drive the engine and if it can't drive
the engine successfully, if let's say the engine is a heavy engine, it takes a while to spool up,
there is a opportunity for the rear wheel to lock up completely. Locking up on its own isn't
really a problem, but it represents a loss of control and in that moment, your control
over the motorcycle, your ability to accelerate, brake or change direction is completely hampered
and when you learn the technique of rev matching or blip shifting, this problem just goes away.
Now what I'm going to say next sounds complicated, but it's much easier to do on the motorcycle than
to explain it on video. The physical motions that you go through when you're rev matching is actually
quite complicated for this hand initially while you learn and after that it becomes second nature
and that is to be able to open the throttle, close the throttle and operate the brakes at
the same time because we're assuming that most of the time when you're downshift you're also on the brakes.
The most extreme situation is you're at the racetrack you're about to enter a corner and
this is the braking phase, you are on the brakes, but you also need to get into the right gear for
the exit, so there's a lot of activity happening in that narrow slice of time. Out on the street,
the time is not that restricted, but the action remains the same, so what you're going to learn to
do is take your right hand, you have your fingers operational, so you are actively squeezing the
brake lever very hard at the racetrack, may not be so hard on the street and at the same time,
your throttle hand has to be able to move, create a blip as in the revs rise and fall that's called
a blip, you should be able to blip the throttle and hit the brakes at the same time. Initially,
you will discover that when you do this, you managed to change the brake pressure and can
be quite uncomfortable, but that's the technique that you're trying to learn where you can maintain
a steady brake pressure while being able to move the rest of your hand and create a blip.
But why are we doing this at all? And the reason we are doing this is because we're trying to match
revs. Now it sounds like a complicated term, but it's really simple if you think about it. So let's
assume that for the purpose of this video, we have a motorcycle with a two-speed gearbox and I'm only
using two speeds because it just simplifies the problem, it applies the exact same way to a four,
five or six speed gearbox. So let's assume that this motorcycle is able to do say 50kmph in first
gear and second gear both. Let's say that in first gear, if you have to do 50kmph on this motorcycle
with the current gearing it's going to sit at let's say 5000rpm, if it does 5000rpm in first,
for the same speed, when you go up the gearbox when you go into second gear, the revs are
going to drop, so let's say they drop to 4000rpm. Now, this is an easy part of the process because
as you go up the gearbox, as you go from first to second, the amount of strain on the system reduces
because the engine speed slows, although your physical speed as you travel through
time and space remains roughly the same, right. But when you go back down into first gear,
the amount of strain in the system is increasing because you're going from 4000rpm to 5000rpm and
remember, even a slow human being will still make a gear change in well under a second, which means
the engine has to find it within itself to gain a full 1000rpm in let's say about 0.6 or 0.7 of a second,
right? That's where the strain comes from and that's where the idea of rev matching comes from.
The idea is that when I go from second to first, I go from 4000 to 5000rpm, I make a way
for the engine to find the extra 1000rpm, I help the engine and the way we help the engine is
by blipping it right. So you're on the brakes, when you start making the gear change just before
that you're going to blip the throttle, remember the clutch will come in a little bit, you don't
have to pull it all the way in but it certainly has to be past the friction point of the clutch
where the engine drive is at least partially disengaged so that you reduce the load on the
system during that time, right, which is why I said, it gets complicated when you hear it because there's
a lot of stuff going on, but on the motorcycle it falls into place really really easily,
so stick with me here, so the idea is we are, say half clutched, again, half clutching for a long
distance is a bad idea, but you will have clutch a motorcycle regularly when you're downshifting. But
you don't really need to bring the clutch all the way to the back, so you're half clutched, you're on
the brakes and now you blip, so what happens when you blip because you're half clutched is your speed,
physical speed doesn't change by much, if you do it correctly, it won't change at all and that's
part of the process of the technique that you're learning. But when you blip it, the revs go from
4000 to let's say, 6000, because it goes, whoo, that's a blip, right, not, that's acceleration,
right? So you've blipped it, it's gone from 4000 to 6000rpm and the trick is to make the gear change
and release the clutch roughly when the engine is back at about 5000rpm as the revs try to fall
back to roughly 4000rpm. Did you see what we did there? We went from 4000rpm, we helped the engine
a little bit, and we got it to 5000rpm and made the gear change, which means the wheel speed and
the engine speed, the correlation between the two which goes through the gearbox remains the same,
although we change the gearing completely by selecting another part of the gearbox to use
that in sum is rev matching. The same process applies exactly the same way to a two-speed, three
speed, four-speed, five-speed, six-speed gearbox. If you had a nine-speed gearbox, you'd have to blip
that many times as well. What that means is if you're going from sixth to first, you should be able
to do it with five blips, but blips, they sound really good, so often, you will use extra blips
long after you've already reached first because hey, they just sound good and when you come into
a place where your friends are standing, and you're pulling into a stop, going boom, down
to a stop does sound better than, tick tick and you come to a stop, it is just cooler, so it's
both cooler and better for your gearbox, it sounds great and it is better for your control over the
motorcycle, so honestly, there is no downside to rev matching. Now the question that we normally
get at this point is if I have a slipper clutch, do I really need to rev match? And the answer to that
is technically you don't need to rev match if you have a slipper clutch, especially if the slipper
clutch is good enough to deal with the differences in the revs because that's what it's there for.
But as I understand it, rev matching is a good technique to learn because A, you can't guarantee
that all slipper clutches will be good enough and B, it's a good technique to learn because it's
just part of riding a motorcycle well. So whether I'm riding something with a quick shifter or not,
whether I'm riding something with an auto blipper or not, whether I'm writing something with a great
slipper clutch or not, I will generally try to blip shift down the gearbox because I think it sounds
cooler, it's better for the motorcycle, and it's an important technique to have on your side. And
that's all you need to know about rev matching. If there's more questions you've got, leave us a
comment. If there's other things that you think should be featured on Simplified, leave us a
comment as well. Thank you so much for watching. This is PowerDrift, this is Simplified where we
take complicated automotive ideas, break them down into simple bite sized pieces that you can digest
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