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GCN’s DIY Aero Road Bike – It’s Free, But Is It Faster?

GCN’s DIY Aero Road Bike – It’s Free, But Is It Faster?

– We can all get aero for free. I mean dropping your head,
tucking in your elbows, minimising your frontal area. It means you can actually go
faster for the same power. But taking it to the next
level involves spending money. – Yeah and the trouble is aero equipment can tend to be quite expensive, so it can take a lot of money. However, the question is
can we do it for free? – Can we modify a bike to
make it more aerodynamic? – How much faster will it go? (calm music) – So here we are and
the plan is to transform Si’s commuter bike into a
super-duper aero-machine so that he can shave five
minutes off his commute and sleep in a bit longer. So here we are, we have
this beautiful Orbea. Stefano, talk us through what you think is the best option for
speeding up the bike. – Well, as a first idea, let’s
try to close all the frame, to avoid any gaps between tubes and so on, to avoid air passing on the frame. So, all the air outside the frame. – So keep the air outside the frame. So every gap is slowing
you down basically. – Yeah, we try this way. So a fairing covering all the frame. – One big fairing, that’s
the way we’re going. (calm music) – [Emma Voiceover] So what
does our experiment involve? Well, we’re going to try to
use cardboard and duct tape to try to improve the
aerodynamics of the bike. Since we can’t reduce
the frontal surface area, after all, we’re not going to
chop anything off this bike, the way to minimise drag is
to make the shape of the frame such that turbulence in a work is reduced. How? Reduce air disturbance by
encouraging more skin friction. Air disturbance creates turbulence and covering gaps in the frame will reduce this air
disturbance, in theory at least. – And red is actually faster
they’ve shown, haven’t they? I mean someone has
shown everything really. Here Si is cutting out
a gap for the front mech because it’s always handy if a bike works as well as being super aero. – [Emma Voiceover] This also includes filling in the gaps behind wheels, and frame, and seatpost, making cardboard fairings basically. (calm music) – That’s actually pretty
good frictionwise. That could be a ceramic
bottom bucket for all I know. Smooth out those wrinkles. Oh, the size on the case. – That’s good, yeah, look at that. – That is looking sleek. – Okay, Emma, do you
wanna do the honours and– – I’ll do one side. – christen our bike. – Wow! Now we’re going fast. So, shall I get suited up then? And we’ll give this a run
before we tackle the wheels. Let’s do it. – Yeah, let’s do that. ♪ You got me down again ♪ (energetic music) – And we’ve reached 40
kilometres an hour, wind speed. So here, on this screen
in the control room we can see, top number on the right is cadence in rotations per minute. The next number down is the wind speed in kilometres per hour, 40 in this case. And the third number down is
the drag force in newtons. And that is literally the
backwards force on Si, thanks to his aerodynamic resistance. And when it’s green that
means that it is lower, as in better, less drag
than on the previous run which was the controlled situation of Si without the fairing. If it’s red, it means it’s
higher than the last run. Now obviously you can see it’s varying between red and green here. That’s because we gonna run this test for at least two minutes
and take the average from those two minutes to see
what the real comparison is. – Well, I’m not gonna lie Emma, that was a pleasure to ride actually. There were a few moments earlier on where I was frankly petrified
that bits were gonna fly off. – We were worried too, but
we didn’t want to tell you. – Terrible paper cuts, and then ruin the priceless wind tunnel. But once I got over this fact that the duct tape was
holding, I just enjoyed it. – And how was the
handling, did it feel good? – Well, I’m glad we didn’t
investigate your angles, let’s put it that way.
(Emma laughing) The results of that first run
were not terribly positive. I’m not gonna lie. So, we’re bringing out the big guns. We’re making a disc wheel. But we’re making it for the front wheel, which may not do much for
the handling of this bike but we’re hoping it’s
gonna ace the wind tunnel. (upbeat music) – [Emma Voiceover] A
disc wheel is, of course, not usually made of cardboard. But the principle I the same as filling in the gaps on
the frame: reduce turbulence. We just have to hope it stays together whilst rotating once the wind gets going. Because it might be a bit hazardous if it detaches and blows away at speed. Please be assured that
we’ve all been trained in the safe use of both
scissors and screwdrivers to chop up cardboard. – Safety first. Gotta put a rotor back on. – [Emma Voiceover] There is a slight problem here, of course. Even if this monster is more
aerodynamic into a headwind, when you turn it so the
wind hits it at an angle, known as a yaw angle, it would
not necessarily be faster. That’s why frame and wheel companies test their equipment at
various different yaw angles. Because in real life,
there’s often a crosswind. There’s also the question
of whether a bike like this, with a front disc wheel
would be rideable at all in any kind of crosswind. – It’s not often I get
nervous on an indoor trainer. A mighty relief to have
got through that run with a homemade front disc wheel, which incidentally we do not
recommend that you try at home. But the good news, at least I think, is that I saw a lot of green
on the real time screen which I think means that we
may have become more aero. I just don’t know what went wrong. I mean, we invested so much
time, effort, duct tape. We’ve converted a beautiful Orbea Terra into what is effectively
an unrideable monster and we haven’t saved any watts. What’s gone wrong, Stefano? What have we done wrong? – It’s hard to reply. Maybe cardboard is not the
best to make an aero bike. – Okay. I take your point. – [Stefano] You should have
a more aerodynamic rider. (Si laughing) – Well there was that. I could have maybe bent my elbows and we’d have saved 20 watts. But, all jokes aside, it’s
obviously very difficult and time consuming and
incredibly expensive to make an aerodynamic bike. But, would we expect to
save that many watts anyway if we had managed to do something? – [Stefano] The research is going on so we can save some watts. We should find out how. – You said that I could be more aero, we could have a more aerodynamic rider. What can I do to save watts? – Okay, you have to
reduce your frontal area. So, try to be as small
as possible on your bike. So, head down, narrow your elbow, as narrow as possible. And to reduce your frontal
area, this is the best. – Okay, so drop head, pull
shoulders in, elbows in, and I can save, how
many watts could I save, do you think, at 40km/h? – [Stefano] Difficult to say but also up to 10% drag reduction– – [Si] 10%. – [Stefano] Yeah. – Okay, maybe we’ll do that
next time instead of duct tape. Well, I think it’s fair to say
we have failed spectacularly to make any kind of
modifications whatsoever to that lovely Orbea Terra other than to effectively make it
completely unrideable. – I guess it just goes
to show that aerodynamics is quite a complicated subject and making a bike fast is
really quite difficult. You can see why a lot of bike companies and teams spend a lot of money
trying to make it happen. – Right, now we have to give a huge thanks to Politecnico Milano for having us, allowing us to use their wind tunnel. And also providing us
with so much expertise even if ultimately it was
quite a futile effort. But, they were absolutely brilliant. – They were also very, very
good at sticking cardboard down. – Yeah, they were. Multi-talented guys. Right. And all that’s left to be said now is please give this video
a big thumbs up as well if you’ve enjoyed it. And if you wanna watch another video from right here in the wind tunnel, not quite so left field perhaps, we tested to see which is the fastest way of carrying luggage on a bike. – Check it out.

100 comments on “GCN’s DIY Aero Road Bike – It’s Free, But Is It Faster?

  1. Do a Graeme Obree, as well as have god-like levels of pain tolerance, and you'll pull it off without the need for cardboard bikes.

  2. You have spent few ours in the wind tunnel. Well-well. This elegantly demonstrates that those guys at RD who develop stuff to go faster/lighter do better do fantastic job.

  3. I don't think these tests are the most reliable I have ever seen. Even a slight change in position from the first to the second measurement can completely disturb the result. Secondly, the surface of the cardboard would be very important to determine the Cd (coefficient of drag), as you put tape on it, the Cd will increase. Thirdly, the bike and frame can only save you about 3% in term of drag force. If you really want to decrease the drag force, you will have to look at your position. Mainly, you have to reduce your frontal area (the area of your body that "hits" the air). If you want to know more about frontal area and how to reduce it, you can visit:, this tool is well know within the cycling industry, Team Sky is only one of its many users.

  4. The most aerodynamic is a drop shape profile what was not the case in this test. The back part must have a huge drag.

  5. Aims to increase skin friction for a smaller wake. Leaves wide-open gap in the back that is basically a parachute.

  6. Didn't show the numbers? Show its mostly in the green but then say didn't work at all? Left the back end open? Expensive bike company shill says I.

  7. Ah, pointless challenges and a woman trying to pretend she enjoys discussing bike-related issues, all to make it appear that the cycling world is not dominated by men and that women too can be obsessed by bikes(even though they`re not). Fake equality sucks !

  8. Women discussing bikes/cars are like men who talk about make-up and Chanel handbags- You can tell early on that something`s not right.

  9. You do not want to fill in the middle of the bike where the legs are, as it just transfers more drag to the legs and more wetted area drag. It is better to just use like 7 to 10 mil plastic to make aero airfoils of the vertical round stuff and to extend the seat post tube to extend and shadow the rear wheel, just like high priced bikes do in carbon. Also do the fork and seat stays into more aero shapes. Having done it, it really is quite easy (and weighs very little). But the biggest drag is the hips, which do a great impersonation of a parachute. That can be addressed as well, but to do it right requires some blow molded plastic of the right shape, suspended on a bearing above the head tube, as it will not turn with the handle bar. I have one not done "right", but it will carry lots of water and a pie with veggies to boot. LOL It really is much better than without it. And despite my poor construction, only weighs a couple pounds and is removed easily with one reusable zip tie. It shadows and supports my upper body. I have drop downs, but I think a straight bar would make more sense. But having a support for the upper body is huge for long rides, at least for me.

  10. Come on everybody at GCN! Can't you get Emma a proper fitting T-shirt? In the last shot she looks like the little girl who wears one of the old t-shirts of hear father… I propose you get her a proper fitting size and Si or whoever appears does that video with hear has to equally wear one of the shirts of that size for the whole video 😀 Would be fun though, at least 🙂

  11. A disc wheel gets rid of the spokes whipping round so should take less power to just make it go around, I don't think you measured that.

  12. 2:26 Am I the only one to bring up the fact that noisy freewheel hubs mean increased frictional drag while coasting?

  13. Now, would it be prudent to have a light weight skeleton frame mointed on handlebars where a rider would mount the bike, grab and pull/unroll a plastic wrap from behind their head or a backpack pulling it straight forward and then down securing it on the front of the frame or handle . This would make a disposable/rewinding aero faring of sorts.

  14. I’m an mechanical engineer and love bike tech… keep Simon in that wind tunnel with more experiments please!! Totally agree with Stephano, Simon”s profile probable accounts for 60%+ of the overall drag, so you”re only getting marginal gains on the bike improvements. You may get more improvements just by making his aéro. The flared-out cardboard at the back probably doesn’t help either. The cardboard should have extended past the rear wheel and connected behind the wheel to reduce airflow separation.

  15. Good job reinventing a sail for cross winds. I'll call it the Jib.
    It's actually a good idea for a fair weather bike, but the efficiency drops below 30mph. It makes sense above 30mph on an ebike, but hell if you hit a good cross wind on a light weight bicycle. Motorcycle fairings do make them go faster, but they are much heavier and can take a cross wind better.

  16. How Come that a Road bike covered to be aero, Not Aero. Meanwhile MTB side, A MTB covered with cardboard to be made aero, Had positive results?

  17. Dudes! A small handlebar mounted fairing foes the trick. Banned by racing wallahs but supported by peer reviewed literature. I read this about 40 years ago in a Scientific American article about human powered transport.
    Also, please get racing wallahs to allow any size wheels so we van find out what works best.

  18. So it appears that an aerodynamic bike is only aerodynamic when situated alone in a wind tunnel. As soon as you place a rider on top the advantage disappears.

  19. why putting all your effort in cutting and taping the cardboards? Just stick as many "Turbo" badges on anywhere on your bicycle and you'll get an instant 200 asspower

  20. Cam tail is worse than even round tube, what you made at the tail end is worse than a cam tail, close that end off…

  21. they lie a cardboard fairing is miore aero than exposed frame , and they did not show data so fuck this test

  22. If you attach a knife on the front of your stem, will you CUT through the air? Ha… Ha…
    What if you attach a knife on your rims? Can you make wicked SHARP turns? Ohoho…

  23. Really strange results, every lenticular wheel have good savings, and more in front wheel (more dangerous but a lot more exposed than rear). Too the frame idea is obvius.
    Probably no was the ideas, but small details of the fitting or cutting was bad.

  24. Can you please do a video where you figure out how accurate the calorie calculations on Zwift, Garmin and Strava are. If i ride the Zwift Watopia Mountain Loop with a power meter all 3 bits of software will give me different results. Strava is always the highest. Which one is most accurate? Go see those nice fellas at the University of Bath.

  25. Now if you made a kind of plastic bubble around the bike that was teardrop shaped THEN you could be more aero.

  26. I just want to note that the duct tape design is not an ideal aero dynamic shape. As important the leading edge of a shape is the trailing is as important if not more important. The fact that you had a giant gap on the back of the bike means the air can vortex in words and create a large amount of drag behind the bike slowing it down. Airfoils are by far the most aerodynamic object. So maybe the issue with the cardboard bike isn't the cardboard but the engineering…

  27. Hi GCN, you do wrong with duct tapes you should go with glue or you should use plastic or fiber glass instead of cardboard. like if you love this suggestion.

  28. You should have tested a recumbent bike a long side just to see how much drag you can remove by riding in a different position

  29. @GCN why didn't you try to build a frame that starts at the middle of the front wheel and bends side-wards to hide the riders legs, so the air can flow smoothly around him. In another video you said that 80% of the air resistance comes form the rider, so it makes a lot more sense to reduce it on the rider than on the bike.

  30. This seems like a HUGE frontal area. Why didn't you scrunch down during testing?

  31. The rear half of the frame cover where its over the rear traingles is the problem, because the wheel has to sit in it theres a big void which creates a vacuum behind the fairing, cut the rear triangle section off so its just the front triangle and you're good to go.

  32. The rear of the bike has a low pressure zone that's pulling on the bike, creating drag, slowing you down. Try to close that up and you'll be better.

  33. Even the cheapest bike in the world is very aerodynamic, unless you can run more than 80 km per hour so aero bikes is just marketing trick

  34. I think you should have tried a fairing on the front wheel. O.K. back to the lab GCN. Keep the frame fairing and probably the disc wheel as well.

  35. Cool idea…but Emma as a presenter is as exciting as watching grass grow~ gotta go. Not everyone 'should' 🐝 a presenter.

  36. Just because you're stupid.Your contacting surface is larger.The material which is cardboard would absorb and be deformed that increase the surface.

  37. We have the technology to build a safe, comfortable and efficient aerodynamic narrow tracked vehicle that is capable of both high performance while yielding incredible fuel/battery range, yet we ignore it…You could allocate special lanes, to these narrow tracked vehicles, which would reduce rush hour traffic . These vehicles would be everything a motorcycle is except as safe as a small car, comfortable and much more efficient.

  38. An enclosed bicycle hit 90 mph/144 kph on a flat Nevada road under its own power. So we know it works, but it most effective when you enclose the rider and bike in a bubble in a recumbent or seating position.

  39. This bike in now a sail, or a kite. Suggest, once you're outside again,
    you change direction with each change in wind direction. Good luck.

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