- Hmm, that'll do.
Well, I am of course joking but it is surprising
how many athletes overlook tire pressure
and the importance of them.
And after all, they play a pretty big part
they're your contact point with the ground.
They provide you traction whilst aiming
to reduce your rolling resistance
and the pressure of them, is very important.
It changes that massively
so today I'm gonna be running you through
your tire pressures for a triathlon.
Right, you see these numbers on the sidewall here?
Well, they're on pretty much all tires
and they are the recommended maximum pressure.
If you're like me you may well have thought,
ah, it's good conditions, it's race day.
I'll just put them up to somewhere
near the maximum recommended pressure.
Very sci ency stuff aye?
Yeah, not really.
Since then I've learned a lot more about tire pressures
and in fact, higher pressures aren't always the answer.
A lot of the latest research is showing that low pressures
actually have better grip, better comfort,
and even less friction or rolling resistance.
So what should you be riding
and how do you work out?
Well it actually comes down to a number of factors
including: the weather, the temperature,
the surface that you're riding on,
the tires that you're using, and even your own body weight.
So let's take a look into those.
(upbeat music)
See when a cyclist sits on their bike, the tire compresses.
How much the tire compresses
depends on both the pressure within that tire
and the weight of the cyclist.
Now there's a load of theories out there
as to how high you should pump your tires
depending on your weight
but the main trend is that heavier the cyclist,
the higher the pressure.
Pretty obvious stuff aye
but to complicate things further
as the tire width decreases
the pressure in the tires should increase
and obviously our body weight distribution
varies throughout the bike.
So should generally have a higher pressure in the rear tire
as more body weight is placed over that rear wheel
and less pressure in the front wheel.
Well this leads us nicely onto rolling resistance.
Now rolling resistance is friction
and we don't want friction.
We want to go fast.
The greater the friction, the greater the rolling resistance
and that is often caused by an under inflated tire
and what happens with an under inflated tire
is that more of the tire is in contact with the road
and therefore causes friction.
But interestingly, an over inflated tire
can also increase rolling resistance
and what happens there is that
the tire essentially bounces along the surface of the road
rather than rolling smoothly along it
and also making it, pretty uncomfortable.
But let's throw grip into the equation here.
It's a pretty important job from the tire.
See the more that the tire can conform to
and make contact with the surface of the road
the better the grip.
So the tire that's being over inflated
and bounces along the surface of the road
isn't going to have as much grip
as a tire at a lower pressure.
Yeah, it's pretty complicated stuff isn't it?
So a couple of the main factors
that we should be considering
when we're heading out on a ride
are the conditions, the riding style,
and also the surfaces that we're going to be riding on.
If you're heading out for a weekend pedal
down some country lanes then you can afford
to run slightly lower pressures in the tires
both for comfort, and for grip.
But then you might be inclined
to run slightly higher pressures
for something like a triathlon or a time trial
where you want to reduce that rolling resistance.
So, I'll fee opting for something slightly closer
to that recommended maximum pressure.
It's fine if you're going to be riding
on glass, smooth, roads.
But let's be honest.
How often do we find those particularly in the U.K.?
Say where you can, do your research on the course
and the surfaces that you're going to be riding on
and consider dropping the pressure a little bit more
if you going to be riding on wet surfaces.
So there are a number of different calculations
and tables out there to help you get the pressure
for different tire widths and different rider weights.
But, today I'm going to use
the Quarq TyreWiz app to help me.
Now before I explain what TyreWiz is
let's just use the app to work out
what my recommended tire pressure should be.
Right it's recommending 84 PSI in the front
and 89 PSI in the back for me and I'll be honest
that's actually a little bit less than I'm used to
but it's not a million miles off
and I do trust these clever folk at Quarq.
Now TyreWiz is actually these clever devices here
and they're essentially an extension
of the Vowels just here and they go in
inner tubes, tubular tires, and even tubeless tires.
All that is required is to have a removable valvco
which is this lil pit, yeah.
Well they read the pressure of the tires immediately
as you're pumping them, as you're riding them,
even as your getting a puncture,
but let's not hope for the latter.
Now they then connect to the app on your phone,
so you can see in real time
what the pressures of your tires are
and if you're drifting outside of that recommended range
and it'll even connect to most bike computers.
Now there is actually something that I'd really like
to explore with tire pressures
and by using these devices
and for that I need a good climb, hmm.
I'm thinking Miyoka.
Yeah definitely Miyoka.
This definitely warrants a trip to Miyoka.
I'll be honest this idea of temperature change
and pressure change has intrigued me for years.
I mean I understand that theoretically
as the tires heat up through traveling at speed,
the friction, the braking,
that the pressure in the tires increases.
So I thought I'd actually investigate this it is a bit
so I've taken myself to the top of this nice long climb
in Miyoka where I know
I'm gonna to be traveling at some speed
rounding some corners.
I'm already so up high to the test.
See what my pressure is like at the bottom.
Currently I've left it at 84 in the front
89 in the rear as suggested
but let's check again at the bottom.
(upbeat music)
Right, that was really good fun.
I love that it's a sense,
so now I can check the pressures on the Quarq TyreWiz app.
The front tire is around two PSI higher
than when I started at the top of the climb
and the rear is more or less the same
which has surprised me.
I thought we might have seen an increase on both
but I think the reason why we're seeing that increase
on the front is where I'm basically scrubbing the speed
a little bit more with the front brake
on a descent like this.
So what's happening is the rim is heating up
that then in turn is heating the tire up
and then the pressure within that tire.
I think if I was riding my bike for longer
putting weight through the saddle
that then is going through to the rear tire.
We might have seen a bit more
of an increase in the rear tire
and plus we have a longer descent.
Either way that's been really interesting.
I think this could be a really useful tool.
If you're looking to sort of fine tune your performance
and even comfort as we go from different courses
different races and even riding in different conditions
and for those weight weenies out there,
that might be worried about adding
something extra to their already lightweight bikes
these devices just come in at just 10 gram per unit.
So barely noticeable really
and as I showed earlier they're quite easy to switch
from bike to bike and wheel to wheel
and you could even maybe train with them
and then take them off for race day.
(window closing) (plane zooming)
Woo what a trip.
Well you might have been hoping
for a magic tire pressure on today
and unfortunately it's not quite as simple as that.
Though I would say next time you're heading to a race
and you're pumping the tires up
just take into consideration some of those factors
that I've discussed in today's video.
Or better, start playing around with different tire
pressures for your day to day training.
Now if you like to see more videos from GTM
just click on the globe and subscribe.
And if you'd like to see a little versus between a clincher
and a tubular tire and changing it for race day
just click up here.
If you'd like to see how to fix a race day puncture
for a clincher tire just click down here.