- Choosing the right wheels for race day can be so tricky
and rightly so because they can have a huge affect
on your performance.
- Yeah, it is always a question of balancing
the aerodynamic advantages of a deeper wheel,
against the slightly lighter weight
and potentially even the greater stability
of a shallower wheel.
- Well, what about a disc?
I mean, we see the pros riding them
they look fast, but are they right for us
and when would we want to use them?
How do they compare to a deep section wheel?
- Well with the launch of our partners new disc wheel
the Enve SES disc we're gonna be putting it up against
one of their shallower wheels, the Enve SES 7.8
to see how they compare, but also to help explain to you
how and when they may suit different riders
and different courses.
(electronic noises)
(electronic music)
- Before we go any further,
let's take a walk down memory lane.
Back in the mid 1980's,
Francesco Moser broke the 1 hour record
indoors on a track, using both a front
and a rear disc wheel.
Now this was more or less the first time
that we'd seen disc wheels in use
and in quite some style so it's not a surprise
that it made some impact
and it suddenly increased the popularity of the disc wheel.
Especially amongst tri-athletes, as well as our dedicated
time trialling friends.
- Well it seems that tri-athletes are quite often
unsure as to what wheel type they should use,
to start off with I thought we'd talk through
the deep section wheel and the benefits behind it
and what makes them so fast.
You can see that it has this air foil shape to it
and that helps it to pass through the air more smoothly
when you compare it to something
like a shallow box shaped rim.
When you think about it, you've got the tyre
as the leading edge, that cuts through the air,
and then the air then passes over the rim
and the idea behind the deep section rim
is it allows they air to pass over smoothly
and bring it back together in a clean fashion, which,
when you compare to a shallow shaped rim again,
or a shallow box shaped rim, it can't do that.
The air comes back together in a messy fashion,
more turbulent, and that creates drag.
Secondly, deep wheels can almost create a sail affect.
So when the air flow follows over the wheel,
at an angle it can almost create a slight forward thrust.
So actually a wheels own drag can decrease
as the wind angle and wind speed increases.
Obviously to a point, but we'll get into that
a little bit later on.
- Now on to the disc wheel, the dawn of all aero wheels.
The wind passes smoothly over the surface,
cause there's no break in the surface
so you're not gonna have that turbulent affect, or any drag.
As for that sail affect that we mentioned earlier,
you can see it doesn't really get any better than this.
Lets get this show on the road,
I think it's time we put these wheels through their paces
to find out whether one is faster than the other
from either of us.
- So we're gonna be doing a flat 5 km time trial
along the Queen Ka which is part of the Ironman
World Championship course and
it's very famous for its strong winds.
In fact today, it's recording around 13 km/h
coming at us from around a north westerly direction.
A nice crosswind to try the wheels out with,
but nothing too severe.
- Well Mark, you're gonna be holding around 300 watts,
and I'm gonna be trying to hold 200.
(tense music)
- Okay, so starting off with the deep section wheels
flat time trial, here I come.
- Okay it's my turn to test out the deep section wheel
on the flat, here we go.
(competitive music)
- Okay I'm going full aero now, my second run,
on the disc wheel. Let's go.
(tense music)
- Okay, same again still holding 200 watts
but this time I've got the disc wheel in the back,
so let's see how fast I can go.
(tense music)
- Well that was good fun,
we were absolutely flying along there weren't we.
- Yeah, it felt pretty good.
- Yeah well my time on the deep section wheel
was 7:02 seconds.
- [Heather] While I was 7:50 seconds on that one.
- [Mark] And then on the disc wheel,
I was 6:49 seconds, so considerably faster actually.
- [Heather] Yeah, same, well I was quicker
with a 7:43 on this.
- And I have to say, I felt like
I was really getting that sail affect
from the disc wheel. - yeah
that I was flying along and it just felt so easy
so smooth.
- Yeah I mean it's the first time I've ridden a disc,
and I loved it, felt pretty cool.
- Obviously not all courses are pancake flat,
like that section of road that we've just used.
That is where things start to become
a little bit fuzzy and confusing for people,
because a disc wheel obviously has more material on it,
so they tend to weigh a little bit more.
I mean if you take this Enve SES disc,
it's new disc wheel, it's a fraction heavier.
It's remarkably light but still around 1125 grammes.
- Where as this SES 7.8 deep section wheel
weighs around 950 grammes so the question is,
do you want to be carrying that extra weight
and what difference will it make
when it comes to a climb?
Well we've come out of the town of Kona
to this hill here, and we're gonna be riding
a distance of approximately 3 km
that's got an average grading of six to seven percent.
- We're gonna be making sure that we start and finish
at the same point each time and given that it is a hill,
we need to make sure that we get up over that hill
so we're gonna bump up our upper fraction now.
So I'm gonna be riding at 350 watts,
and Heather is gonna be riding at 250 watts.
(electronic music)
- [Heather] Yeah I mean as expected it feels pretty normal,
I am used to riding deep section wheels
and when it comes to a hill
I'm happy to be out of the saddle, in the saddle,
and it's gonna be interesting to see how it compares
to the disc wheel.
- Okay, same thing again, same hill, same power,
but now I'm on the disc wheel.
Let's go.
(electronic music)
I actually feel alright when
we're on the shallower gradients but
as it starts to pick up there's a
sort of fluctuation up this climb.
I do feel it a bit more in those slightly steeper gradients.
I think it's just that additional weight,
perhaps when I'm getting up out of my saddle,
it's just a little bit more material maybe
just moving from side to side
a bit more weight.
Just feels a little bit different, a little bit harder.
Well that is the hill climb complete
and that was quite hard work.
- Yeah I'm glad that one's over.
- Yeah well on the deep section wheel ,
I was around 7:46 seconds
- [Heather] I was around 8:50 on this one.
- [Mark] And then on the disc wheel
I was a fraction slower, I was 7:55 seconds.
- [Heather] I was also slower on the disc with 8:56.
- Yeah which I think has gone to show
that we really should consider our wheel choice options
if you are doing a course that is slightly hillier
you're going at gradients that may be above six percent,
you're losing that aero dynamic advantage
and you're losing your speed.
A shallower wheel, slightly less weight,
maybe has a little bit more advantage.
- Okay, what about the speed that we're travelling.
This isn't actually something that I considered before
but it's partly the reason that Enve have taken
so long to release a disc wheel.
- See, traditionally, a lot of wheels are tested
at around the 50 km/h mark, and obviously
they prove that disc wheels are faster.
But then how many of us are actually travelling
at 50 km/h during a race, or at least for that long
and particularly given the length of a bike leg
during a triatholon.
So Enve have tried to be realistic
in their approach to this in the past.
That is why they've tried to optimise wheels
that are suited to the speeds
that most of us are travelling at.
According to their research,
they've found that an open spoke deep section wheel
to be faster for the speeds
that most of us are travelling at.
But they have found that there is the need for a disc wheel
for some of those faster athletes
and potentially on some of those shorter courses.
So if you are an athlete that's gonna be travelling
at over 27 m/h or 43 km/h
then a rear disc wheel may well be
the better option for you, depending on the course.
- However, the wind is another factor
that you need to consider.
We've already mentioned the sail affect,
so the deeper the wheel the greater the sail affect
and obviously the greatest when it comes to the disc wheel.
If you've got very strong cross winds,
or even worse gusts, it can start to get
a little bit harder to control your bike
when you've got a disc wheel on the back.
That's actually the reason that disc wheels are banned
here at the Ironman World Championships in Kona,
because of those strong winds that
come down off the mountain and can really gust
and catch riders out.
It's a worse effect the lighter the rider is as well.
It just makes your bike that much harder to control,
so you need to consider this and think about
the energy your gonna be wasting trying to control your bike
compared to aerial benefit you'll get from a disc wheel.
- So in short, a disc wheel is clearly fast
if perhaps you're planning on racing a short distance,
a flat course, or expecting to hit high speeds.
But if you're not expecting to hit speeds
in excess of 43 km/h, or for long,
then a set of deep section wheels may be the better
and more versatile option for you.
- As we've mentioned, this wheel isn't suitable
for all courses.
It is a big investment for performance,
but if you've decided that's what you want to do,
then for certain courses, yes, there is that benefit.
You're probably gonna need to invest
in a deep section wheel as well for those courses
when you can't ride one of these.
Well, hopefully you've enjoyed this
and you want to get all of our videos from GTN
if so, just hit that globe to subscribe,
and if you want to see our seven aero hacks video,
that's just here.
- If you'd like to see our comfort vs aero video,
where I play around with different positions on the bike,
then just click down here.