we're here at the Iron Man World Championships where disc wheels
are banned in today's episode we're going to talk about why they shouldn't be gone
I'm with Dov and Amy from parkour wheels and currently one of their athletes is in the
lead and she's not riding a disc wheel why isn't she riding a disc wheel this wheel's
abandoned for Kona we're racing on an island here as they get out onto the cream case or
the main chunk of the bike course you get some pretty impressive Crosswinds all right today is
actually probably one of the stillest days that they've had for racing here for a while so it's
probably not going to have the same impact but there are days and there have been days here in
the past where you get a massive crosswind and basically Iron Man as an organization
has got nervous and has said that they're just going to ban this Wheels outright to
me that kind of makes sense surely it acts as a sale and you just get blown away no a solid
rear disc wheel is going to stop any airflow from coming through it so you're going to have
a greater side Force coming in on that rear wheel than you would with a spoked wheel where
there's an opening and airflow can come through that's all well and good but we have a sneaking
suspicion or Dove has a sneaking suspicion he's the one who's a qualified engineer that that
decision by Iron Man May in fact be wrong we're gonna go and uh find the only disc wheel on the
island and explain why it's a disc wheel that is so banned here it almost didn't make it DHL we're
in on the game it's distracted should we steal your own disco let's go get it how do we do this
they'll never notice they'll never notice I'm not illegal so we knew from speaking to some of our
athletes and our pro athletes that we've been sponsoring for a while that anecdotally riding
a disc wheel in some of the windier races that they've been doing like on Lanzarote they noticed
that actually they felt more stable on their bike so we really wanted to look into why that is to
do that we've gone back to our partnership with the guys at Nottingham Trent University and use
some of their expertise and actually designed a study to analyze exactly what's going on and see
if we can quantify some of the effects the study involves using some tiny little accelerometers and
placing them onto the handlebars of the bike so as you're riding along we place the accelerometer on
the bar and what that does is that measures any sort of handling instability moment so what do
I mean by that it's not the sort of constant side force that Iron Man are worried about so it's not
the constant wind that's sort of pushing you ever so slightly sideways we're more interested in that
what we kind of defined as the oh God moment the oh [ __ ] moment where you feel that twitch you
feel that moment where you lose control of the bike and ultimately particularly when
you're on a TT bike that's critical because if you're down on the error bars that's going to
force you either up out of the Aero bars onto the Pursuits to stabilize your bike at which
point you're giving away all of the Aero benefits from your wheels or Worse you're putting yourself
into an unsafe situation and that's ultimately what the rule was designed to protect against
what we found is actually relatively counter-intuitive so we now can see
patterns in the data that show that running a rear disc actually improves the handling on your bike
it makes you more stable reduces those handling moments that cause the instability we're still
digging into exactly why but the principle is fairly sound so what happens is as the airflow
hits the rear disc you have upwind hitting the side of the disc creating a high pressure area
on the other side of the downwind side no air is passing through so you've got a relatively low
pressure that creates quite a big differential so the pressure difference here is higher than
it would be with a spoked wheel what that does is it actually moves the center of pressure further
back on your bike towards the disc wheel what it's analogous to is a bit like when somebody lowers
their center of gravity meaning that they're harder to push over so by moving the center of
pressure backwards on the bike you're making it harder to create an instability moment at the
front which means that the bike is going to be more stable running a rear disc the air is never
going to go through it so you're never going to be able to mitigate against that but what we find is
that because the rider's weight is predominantly over the rear wheel that's much less of a concern
you can manage steady Force it's the unsteady gusting winds or people riding past Vehicles
gaps in Hedges back home that's what causes problems and actually that's what we're seeing
a rear disc helps stabilize the next section of this video involves some very weird things that
Dolph has flown over I'm surprised you didn't get stopped at security to be honest mate so vanilla
athlete is third off the bike we're gonna see if we can catch her before we leave in the Run
I think you need a new phone Dove it's literally melting so much I mean we can't
whinge at least we're not running a marathon why have you taken us here
it's the coolest part of the shop nice we've got us a bunch shout out to Bike Works in Kona for
making us cooler we are going home to finish this video but when we've cooled down these Frisbees
oh shade I see clouds four days now your bottom bracket's still making a noise
I tried to fix it but you know no you haven't you haven't tried at all
you've done absolutely nothing we're now cycling up a very big hill because I've booked an Airbnb
at the top of a volcano so when we get to the top we'll show you the gubbins if we get to the
top it looks like Mordor never have I wanted to get to mortar or more one hourly deal that was
the most disgusting ride I've ever done though it's taken us like two hours to cool down I had
a cold shower it didn't do anything Amy's face is red to be fair I'm nearly at Raceway after
sweating it all out so here's some of the weird little things that Dobbs brought with him so
this is an ultrasonic anemometer that's actually designed for sailing I'm not going to tell you
anything about this just yet because we're going to go out testing later in the week so I'm going
to save that surprise for later so that's not for the disc will no no so for the handling stability
um this is what we're looking at so this is a three axis accelerometer
that we just attach to the handlebars and sits just on the bar end there and what that does
is that records any acceleration movement so any handling instability or jerky motion
um which is triggered by the uh by wind catching the wheel and sort of causing that instability
this is all part of our technical partnership with the geising at Nottingham Trent so some
students there have been running um some testing over the course the past few months they've been
recording data on lots of out and back runs comparing a setup with our Chrono spoked wheel
set and looking at that compared to the stability of a Chrono front with a disc rear in combination
with that they've also been running some sort of uh more subjective testing so Riders are asked to
record how they feel in terms of stability safety control and levels of concentration required so
we're using two different methods here we're taking a sort of very data-driven objective
approach with the sensors and we're also taking a more sort of subjective approach in terms of the
writer surveys and the feedback that we're getting both are being analyzed alongside each other and
what's really interesting is the first sort of stages of that testing are showing some really
clear differences between the two setups and it's all pointing towards the fact that running
a rear disc does in fact improve your handling stability and so the next step that we're now
looking at is seeing if we can actually quantify that and put a number to it to say if you run
a rear disc this is how much more stable it's going to make you people talk about the winds
in Kona in particular so we figured well what better course to go out and test on than one
that's so notoriously windy that disc wheels are actually banned we figure that if we can show that
this holds true even here then it really does open up the debate as to should this Wheels be
allowed do you think you'll be able to convince the Iron Man to change his mind I don't think
anybody's ever convinced don't mind to change their mind about anything but uh no the hope
is that if we can show them black and white data then we've made a strong an argument as possible