Bike Tyre Pressure Explained | Road Bike Maintenance

- How hard should your tyres really be
and what is the right pressure?
The first point, if we're starting completely from scratch
is to make sure that you pump up your tyres
to within the minimum and the maximum
recommended pressure that's normally printed
on the side of the tyre there.
Now this one, this Continental,
has a maximum recommended pressure only,
that's 8.5 bar or 120 PSI.
So if you stick close to that,
then you will not go wrong
from a safety perspective, at least.
If you don't have a cycling specific pump
with a pressure gauge on it,
my first suggestion would be to go and buy one
but in the short-term, what 100 PSI feels like,
is actually when you squeeze the side of the tyre,
so not the tread, but the side,
basically you can squeeze as hard as you can
with your thumbs and it will not move very much.
Ambiguous, I know, but you haven't got a pressure gauge,
so what can you do?
Well now we're safe, that is a very good place to start
but it's certainly not the only thing to think about.
We also need to factor in the width of our tyres
and also our body weight as well,
because narrower tyres need higher pressures
than wider ones and heavier riders
need higher pressures than lighter ones
and then just to complicate things further,
we also need to factor in the following points as well.
(light music)
Tyres need to grip, that's pretty obvious,
if you want to accelerate or change direction
or indeed slow down, but a tyre that's too hard
won't deform to the road surface
and so less rubber will be in contact
with the road at any one time,
meaning that you have much less grip.
So ideally, you want to run a pressure
that allows the tyre to compress when you sit on the bike.
Now, believe it or not, loads and loads of research
has been done into exactly this topic
and most people, it would seem,
agree with the work of a man called Frank Berto
from back in the 80s and he worked out
that the ideal amount of compression
was 15% of the tire's total height, although admittedly,
that is a remarkably difficult thing to measure.
(light music)
Brilliantly, comfortable tyre pressures
can also be faster tyre pressures as well
because for just about all of cycling eternity,
we thought that harder tyres were faster tyres
and with good reason, to be fair,
because in laboratory settings, harder tyres
were measurably much, much faster
so they rolled with much less resistance than softer tyres.
However, out in the real world,
on normal, bumpy roads, a softer tyre
absorbs vibration much better
and that vibration really slows you down, a lot in fact.
So, that is why a softer, more comfortable tyre
can potentially roll faster as well.
(light music)
If it's starting to sound like softer tyres
are the way to go, then hold on,
because a tyre that is too soft will start to roll slower
and then they will also squirm around corners,
which makes it particularly difficult to control
and dare I say, dangerous.
And then also, of course,
a softer tyre will be more susceptible to impact punctures.
(light music)
I'm sure you'll have noticed that
I haven't actually recommended any tyre pressures yet
so perhaps it is time for me
to put my money where my mouth is, okay.
I weigh 73 kilogrammes and when I use a 23C wide tyre,
I put 95 PSI in my front wheel and 100 PSI in the back
because there's a little bit more weight over there.
And for 25's, I use 80 and 85 PSI
and then for 28's, I run 60 and 65 PSI.
As I mentioned earlier, if you are a little bit lighter
you will want to run less, so consider putting in
about one PSI less for every one kilogramme of body weight
and if you're heavier, you want to do the opposite.
And if you're working in bar,
then that's probably about one bar
per 25 kilogrammes of body weight that's different.
Now there are loads of really handy calculators
that are on the internet that will attempt
to do this job for you but if there's one thing
that I think you should take from this video,
it's that you should spend time
thinking about what your own perfect tyre pressure is
because it does vary from rider to rider
and indeed, from place to place.
So think about the things that we've just covered
in this video, does the tyre squirm when it gets too soft?
Or indeed, are you really susceptible to pinch flats?
Or, are you about to go for a ride
on the best, most super smooth tarmac in the entire world?
In which case, you probably want to put a few extra PSI in.
Do not be afraid to play around,
stay within the limits and stay safe.
Oh, and there is also one thing,
it's not just your tyre that will have pressure limits on.
If you've got a really lightweight set of wheels on,
then they too may have a pressure limit
although, if they're anything like these Zipp's here,
we've actually seen them being inflated
to over 200 PSI more than the recommended limit.
(explosion) Whoa.
Well clearly, a little bit
of margin for error built in there.
Now, do make sure you subscribe to GCN,
it's very simple and it's free to do it,
just click on the globe and if you're after
some more content, about tyres in fact,
then why not click up there
and we've got a video about how to reduce the risk
of punctures, or just down there,
we've got a very topical one,
the truth about wide rims and wide tyres.
Check 'em out.

Bike Tyre Pressure Explained | Road Bike Maintenance

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