Gravel Vs Road Tyres | How Much Slower Are Gravel Tyres?

(electronic slicing) – A mixture of common sense
and established science tells us that a road bike
specific tire will be faster on a road compared to a
gravel tire and a gravel tire will be faster on gravel. – But by how much? We’re going to do some simple
experiments to find out exactly what the difference is. – And the beauty of gravel
tires and gravel bikes is there all-round capability
with greater tire volume, and more pronounced tread patterns, they give better grip and
performance and comfort off-road. – A gravel tire like the
Continental Terra Speed, is a great all-round performer, but the compromise is
increased rolling resistance when on smooth tarmac
compared to a tire designed purely for road performance
like the Continental GP5000. – Yeah, right, let’s do some tests. – Yeah, Ollie, why are we
out here in the rain though? – Because this is a controlled
environment with consistent smooth tarmac. Don’t worry though,
first test, back inside. – Oh ho ho ho ho, I like the sign of that. (upbeat music) – First up, we’re going
to look at the rolling resistance on the rollers
to see if on a perfectly smooth surface there’s
a measurable difference between the two tires. – The interaction of a tire
with a surface it rolls on creates friction and when
we ride we have to overcome this friction. – And, well, the lower the
rolling resistance of the tire, the less friction you need to overcome. – [Chris] Tire pressure
affects rolling resistance, so we’re going to perform
the test with both tires at 70 psi and also perform
the test with the tires at pressures more representative
of what you would actually use in them. So, 90 psi in the GP5000 and 40 psi in the Terra’s Speed gravel tire. – Right, as you may be
able to tell I’m warmed up but more importantly the
tires are up to operating temperature, which means
Dr. Oliver we can start the experiment. – We can. So Chris is going to try
and ride at a target speed of 45km/h in the same gear
for both of the different runs we’re going to do. And then we’re going to
measure the power required to maintain that speed
with both sets of tires and at the different pressures. This is going to be done using a Quarq Power Meter and the Wahoo Head
Unit we’ve got on the front. Each run is going to be five
minutes long on each different tire and the different pressures. So first run, let’s go. (upbeat music) – Five, four, three, two, and done. (upbeat music) – Chris is now going to do
the next run which is at lower pressure; 70 psi and we
would expect that to maintain the same speed, 45km/h
he did in the first run, he’s going to have to put out more power. – Yep, 70 psi Ollie, five bar.
– Five minutes. – Right, you ready?
– Go! – Can you count me in?
– Yep, three, two, one, go! (upbeat music) – 10 seconds to go. Feeling pretty warm and I can
already see the information right in front of me. I happen to know what is going on. Here we go, and stop. (mellow music) Now I’ve got the tires all
warmed up and I already have an inkling as to how this is going to go. So, I think I might have to
go until I blow on this test. It’s going to be
literally a maximum effort to maintain the same speed. (mellow music) (tires squealing) There we go. So that’s three minutes,
not the full five. But that does mean I can
repeat the test at 40 psi. Ooh, that was harder than I was expecting. (air puffs) Tires are now down to 40
psi, got to warm them back up a little bit for the next
test and then it’s three more minutes to go. (upbeat music) – Time for the results
from riding on the rollers. – Sciency bit, Ollie. – I’ve got the data off your
Wahoo, let’s take a look. – Right then, should we
start with the road, 90 psi. – Yeah, so this was a 28mm GP500 – [Chris] At 90 psi, which is
roughly 6 bar as we discussed whilst we were outside. So, for this test, I averaged
299 watts at 45.8km/h, and that is basically a
benchmark test, wasn’t it? – Yeah, so then reducing the
pressure in that to 70 psi to maintain that same speed,
in the same gear, at 45km/h, you had to 327 watts. – That’s quite a bit more actually. – 28 watts more. – Yeah, essentially 10% extra. – Yeah, that’s significant,
that’s surprising. So let’s look at the gravel
tire at that same 70 psi. This is a 40mm wide gravel
Terra Speed from Continental. – Well then, for the test
we’re up to 449 watts average, for exactly the same
average speed of 45.8km/h. Again in the same gear, so
the cadence was the same. – [Ollie] So, final one,
40 psi in the gravel tire. – Yeah, real world gravel
pressure, that one Ollie, I’m a little bit disappointed
with if I’m honest. I was hoping to do it for a
good two minutes but after one minute 14, I pressed
lap, having averaged… – (laughs) I’m not surprised, 516 watts! – Yeah, but I did go the same
speed; 45.8km/h, so at least I got that. – Yeah, I mean, that’s astounding
how much more power you required to do that. – Yeah, that’s a big difference. – Well, I mean, this is all
well and good and does give an indication as to the difference
in rolling resistance between the two tires and
the different pressures, but, not entirely representative
of the real world on this perfectly smooth rollers.
– No. We need to take it outside mate. – All right then, that feels
like I’m going to get wet today, because it’s raining. – Yeah, we need to find some tarmac. – Come on, let’s go. (upbeat music) – We’re going to be
performing a roll down test, and when I say we, I mean Chris, on this nice smooth
consistent piece of tarmac. Remember Chris, no peddling. – That sounds like my kind of test, Ollie. I’m going to be doing
both runs in the drops in the same position to ensure my aerodynamics are consistent. – And we’re going to
first do the gravel tires and then repeat the experiment
with the road bike tires. Chris is going to roll down
the hill and without using his brakes, see how far he
gets when he comes to a stop, and we’ll measure the difference. – You ready? – All right, standing start, Chris. You ready to go?
– Camera’s on. I’m going to release you.
– Release me. (mellow music) (Chris laughing) – [Ollie] Rapid – [Chris] This is undramatic. – [Ollie] Hopefully he’s going
to pick up some speed soon. – Building momentum. Come on. Oh, come on. Come on! (tires turning) – Normally I struggle to
keep up with Chris but as you can see, without him having
to pedal, it’s quite easy. (upbeat music) – 5.8! – [Ollie] You’re getting some speed now. I’m struggling to keep up. – Six!
6.3! (upbeat music) Oh, we’re grinding to a halt. Oh no, it’s all gone! All of that hard earned momentum. Five point… Oh dear, that’s it. – Well rolling down this
extremely steep slope, Chris has managed to get
this far on the gravel tires and I’ve marked it on the
road with this piece of chalk. So now we’re going to repeat
the test with the GP5000s and see how far Chris gets on those. – Scary speeds, Ollie, they
were, they were scary speeds. (air pressure releasing) – Round two now, we’re going
to do everything the same again but this time on road
tires, so we’re expecting that Chris is going to
go a little bit further. I guess we’ll have to find out. – I’m expecting big things here, Ollie. Count me down. – Three, two, one, you’re released. – Oh, here we go. Build up a bit of speed
off the line there, excellent acceleration, auto-pause hasn’t yet turn itself off. Oh, there we go. Now we’re in, now we’re going. Creep down to the left. – [Ollie] Don’t pedal. No pedaling allowed. – Creep down to the left just like before. We’re up to 4.9, 5.4, oh. We’re already going faster than we were. Basically 3km/h faster that I was before. What does that translate
to after the turn? (upbeat music) Now we’re going straight passed the mark. Still going! Still rolling! We’re still going, we’re still moving, they don’t want to stop. And that’s it. – That cone over there represents
where Chris stopped when he was riding on the gravel
tires and I’m genuinely astounded by this. This is how much further
he’s gone on the road tires. I measured it with my tape measure and it’s 65 feet eight inches. – 19.8 meters, which is frankly a massive difference, isn’t it? – Yeah, I mean, that’s,
well, it’s roughly the same, well it’s a bit further than
the world triple jump record. – Stats for you everywhere. – A long way, and we’ve repeated
this experiment three times and got roughly, give or take
a few inches, the same result each time, it’s consistently
coming out this much further. I really am amazed at
how much further you go– – The top speed on the road
tire is around 4km/h faster as you’re going down back, up to five actually for the fastest run. So, yeah there is a big difference there. – I guess it goes to show you
just how much, well lower, the rolling resistance
is on this kind of tire. But we’re going to do another test. – We are. Gravel? (mellow music) – No real surprises there but
it’s interesting nonetheless to see the difference that tires can make. – I do feel that it was a
little bit unfair though and slightly biased
towards the road tires, so we got the gravel tires back
on and we found some gravel. Same test, only this time I’ll
be adopting a gravel stance, whatever that is. – Watch out for that dog
poo over there as well. – There’s quite a bit
around here, isn’t there? – [Ollie] And release your brakes. Go. – Here’s the gravel
stance, slightly hovering. Oh the speed is unbelievable! So fast! Oh, this is the fastest
anyone’s ever been on gravel. (upbeat music) – Having rolled down the gravel
trail on the gravel tires, this is where Chris ended
up and well, his front wheel is handedly marked by that
leaf that was already there. Now we’re going to try
it with the road tires and see what happens. (air pressure releasing) – We’re going for 90 psi,
which is just over six bar. As we mentioned earlier in the
video, this is representative of a real world pressure
in optimum conditions. Whilst we don’t have that here today, we’re going to use it anyway. Right, road tires, 90 psi,
and Ollie’s waiting for me at the finishing point of the gravel tire. So, I’m going to have to track
stand and set myself off. – [Man Off Camera] Three, two, one. (upbeat music) – Wow, that’s 12 feet. – That means road is 12
foot better than gravel. – Twelve feet further! Right, it’s now raining quite
a lot so you’re going to have to forgive my hood but
I was sort of a little bit surprised that the road tire went faster than the gravel tire there, or further. – Yeah, I mean, we should point
out that this gravel isn’t particularly loose or overly
rough and the road tires do feel a lot faster, but one
thing is for sure, there’s nowhere near as much confidence off-road. Like, I wouldn’t be able
to get up the same grassy or gravely banks on these tires
as I could on the Terra’s. And also when it comes to
cornering, you definitely don’t feel like you want to push
it anywhere near the same. But they do feel fast. – And I guess it does kind of make sense that the road tire would go
further in this situation, in this particular experiment
because the gravel tire is designed to give you
more grip because you need more traction on loose surfaces. And right now, the lack of
traction that these tires are affording you is
allowing you to go further, there is less friction. (mellow music) Well having performed our
three pseudo-scientific experiments, unsurprisingly
the smooth road specific tire is faster than the gravel tire. – Yeah, there is a time and a
place for everything though, Ollie, and today we didn’t
test the gravel tire on any technical gravel whatsoever,
where I suspect it would really shine and in fact
put the road tire to shame. – Yeah, I mean, it’s apples
verses oranges, isn’t it? You’ve got two things that
are designed for completely different purposes and I guess
this means we need a sequel, we need to go and take out
the two tires and test them on some technical gravel.
– I’m free tomorrow in fact. If you enjoyed this video
do give us a big thumbs up and subscribe to the channels
if you haven’t already done so and to see more
road verses gravel content, click just down there. – Yeah, we got epic gravel in Oman. – Oh, that’ll look good.

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