- Are you worried or unsure about what tyre pressure
you should be running on your bike?
Just got into the sport or maybe lookin' for a quick way
to improve, well, here it is.
(smashing sound)
Right, understanding the grip your bike has with the terrain
and how tyre pressure affects that will give you
the confidence to make informed changes
to your tyre pressure.
This is a breakdown of what your tyres are doing for you
and the important things to think about,
so you can understand the feedback they give you.
Plus, this is a big plus, I'm going to direct you
to finding that all-important baseline pressure
so you can start enjoying good grip,
adjusting that tyre pressure to make solid improvements
when the terrain or weather changes.
First off, let's think about the basics
of what the tyre is doing and how it works.
(jazz music)
The contact point is how we describe the ever-changing shape
that each tyre creates at the contact point with the ground.
Simple enough to imagine, it helps us understand
what is going on.
Freeze your riding at any moment, and wherever the tyres
are touching the ground, is creating a stamp-like image
of what's happening beneath you.
Let's think about that shape and how it helps us
understand the basics of tyre pressure and what that means
about what the tyre is doing underneath the bike.
Okay, to illustrate, I have done this incredible drawing
that I'm very proud of, and as you can see here,
we're looking up through the ground as the tyres,
it rolls down the trail, and here, if you've got a hard tyre
what you're gonna see is the contact point is really small.
The tire's standing up proud 'cause he's got a lot of air
there supportin' it, and you've just got this tiny point
touching the ground, that's the moving stamp that's going
down the tread of a hard tyre.
Now, the soft tyre is really easy to understand
is squashing out, there's less air supportin' it.
And the contact point has grown dramatically.
This equals much more grip,
when you're cornering and when you're braking.
So this contact point is a really important thing
to consider when we're talkin' about tyre pressure.
(jazz music)
Okay, let's get a wheel.
Take a look at what is happening with our tyre pressure.
A hard pressure on the ground, if we look at this point here
the tyre profile isn't going to change hardly at all,
'cause there's so much air there.
But the contact point's very small.
And as we lower the pressure, the tyre squishes out
and suddenly that contact point's huge.
Loads more tyre on the ground, that means more grip.
But let's put that bike in a corner,
I think about the forces that'll go through that tyre
and what's gonna happen.
We've got a really low pressure,
and we're goin' through the corner, we're banked over.
The tire's gonna squish down, but it's also the rim's gonna
push to the outside of the tyre like this.
Now as you can see with a low pressure,
the pinch on the inside of the tyre just here
starts to come really acute and it starts to roll,
so that's what we don't want, and that's
what we've gotta avoid with a really low tyre pressure.
So, the lower the pressure,
the more likely the tyre will roll, puncture,
or if you're using a tubeless tyre,
you could lose air through it burping out, excuse me,
through the bead as it comes under more strain.
So all that information starts pushing our tyre pressure
choice back up, and as we do, we start experiencing
less rolling resistance and seemingly faster pace
until you go beyond that sweet spot
and reach the contact point that is too small
and suddenly you don't have any grip for braking
or carving through a turn.
Next question: then how do we find
the sweet spot of tyre pressure, the Goldilocks effect
of not too much and not too little?
(jazz music)
First off, you need a general pressure to work from,
and I can give you that.
I'm gonna say 25 PSI.
And I wish that was the final answer, too.
If only it was that easy, however, this suggestion
is just the starting point that we can work from
and make adjustments from, so either up or down
to create your personal go-to tyre pressure.
So this general pressure is just your startin' point.
The changes you will make really depend on the combination
of riding style, tyre compound and tread pattern,
plus riding terrain and the weather on the day you're riding
Many variables, and that last point about weather,
really makes you realise how important it is
to get confident with adjusting your tyre pressure,
to see your days riding.
(jazz music)
To start experimenting, choose a piece of trail
that's easy to do multiple runs on, and start riding
that trail with 25 PSI in both the front and the rear.
If possible, it's best to do this on a relatively
standard weather day of you're local riding spot.
After a few runs, let some air out of the front,
bringin' it down to 23 PSI, then do a few more runs.
You'll instantly feel the difference.
The grip will be higher because that contact point has grown
Ask yourself if you like the difference.
If you do, then maybe try even less pressure,
perhaps venturing down to 22 PSI and doing some more runs.
The process of elimination is gonna find
that sweet spot for you.
Now with the rear, you do the same, startin' by goin' down
to about 24 PSI and do a few more runs.
The difference in braking performance will be noticeable.
And you might notice a bit of bob in that peddle stroke,
as well, as the tire's now more flex.
So experiment with the pressures up and down
to find the right pressure for you.
It will be the setup that feels good, gives you confidence
and consistency over multiple runs on your little test track
In the end, you'll likely end up with a lower pressure
in the front than the rear.
As a guide, unless you're riding very slippery conditions,
then you probably won't go below 20 PSI in the front.
And unless you're a sort of a heavier rider,
you won't be above 30 PSI in the rear.
Play with it, and find your general pressure, the go-to one.
Only time and experience will teach you more about
why and when to alter it, but enjoy doin' it
because the benefits are amazing.
And this is a big part of becoming a really good bike rider.
Now if you have some experience or knowledge on this subject
then make sure you tell us your general pressures
in the comment section down below.
You won't believe how much confidence you'll be giving
a new rider by sharing those numbers.
Over here on GMBN, Doddy, for instance,
is running 24 in the front, 28 in the rear
as his kinda go-to numbers.
Personally, I'd say 22 front, 24 rear, that'd work for me.
Although Doddy is likely 20 kilogrammes heavier than I am,
so right away you can see how one simple factor
like body weight creates an individual's
personalised general pressures.
Have fun finding yours.
Thanks so much for watching, and I hope it's helped.
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and we will see you next time.