Log in:  

Register

AIR RESISTANCE: influence of motorbikes, bike position etc

A place to discuss all things related to current professional road races. Here, you can also touch on the latest news relating to professional road racing. A doping discussion free forum.

Moderators: Eshnar, Irondan, King Boonen, Red Rick, Pricey_sky

AIR RESISTANCE: influence of motorbikes, bike position etc

13 Jul 2019 04:08

I posted this some weeks ago in the "general news thread". Since there is now a follow up, i've decided to make a new topic for it.

Red Rick wrote:
Logic-is-your-friend wrote:Belgian professor Bert Blocken from universities Leuven (Belgium) and Eindhoven (Netherlands) has done more research regarding the advantage of drafting behind motorcycles. It turns out the advantage is much bigger than expected. In perfect conditions at an average speed of 54km/u, even at 30 meters (!) still an advantage of up to 2.6 seconds per kilometer is gained! Due to 12% less resistance.

At 50 meters behind a motorcycle, the advantage is still up to 7% less resistance.

https://sporza.be/nl/2019/06/27/motoren-voordeel-renners/

Should be much bigger news.

Logic-is-your-friend wrote:
Sestriere wrote:Perfect conditions would imply no wind at all and the cyclist following the motorbike the best possible way? Does the study also make implications about real world scenarios, i.e. cross or tail wind, changing speed and distance to the motorcycle due to undulating roads or the leading rider of the group taking the shortest possible way instead of perfectly following? It would also be interesting to know whether the results only apply to individual riders and single line groups or pelotons as well.


I can imagine the advantage being even bigger with a head wind. With cross wind, the advantage gets a lot smaller. I assume the actual study does go into that further, but the news report didn't.


This guy (Bert Blocken) was in the NOS Avondetappe on Dutch national TV. Those who understand Dutch and want to see it, you can view all episodes of the Avondetappe, via "NPO Start".

https://www.npostart.nl/nos-de-avondetappe/12-07-2019/POW_04304525

It's an interesting watch. I recommend it even if you don't speak Dutch (just for the visuals). He also compared descending/downhill positions on the bike (Alaphilippe vs Froome). Ewan's sprinting position. The fact that a car/bike riding BEHIND a rider also has a positive influence on air resistance for the rider (the car effectively pushes air forward, and creates a "bubble" wich also protects the rider). And that a car/bike riding NEXT to the rider impacts the aerodynamics in a negative way (i guess unless the wind is coming from that direction).

Apparently, ASO has briefed the motorbikes (/pilots) in light of this research, to keep their distance. Other organisations have asked UCI for years, to do this research, but UCI never committed.

Image
Image
Image
Image
Image
Image
Image
Image
Image
Image
Image
Image
Image
Image
Image
Image
Image
User avatar Logic-is-your-friend
Senior Member
 
Posts: 2,602
Joined: 07 Jun 2011 12:17

13 Jul 2019 08:22

Caleb Ewan sprint position is smart, aero matters a lot because power requirement to overcome air resistance increases exponentially with speed. But he gets away with that position by being diminutive, not for everyone, and Ewan makes himself more likely to crash by putting the center of gravity forward.
Chris Froome is not nearly as far forward on the top tube in reality as the rider figure in the simulation of 'Position Froome' . But certainly it's believable that 'his' method is less effective, because of having the head far away from the hands compared to the tight tuck, and also more turbulence unnecessarily behind, in the region between back and seatpost
ClassicomanoLuigi
Member
 
Posts: 579
Joined: 06 Jul 2016 03:20

13 Jul 2019 11:42

They didn't compare both positions. Obviously because one was for sprinting and one for descending. It's possible that Froome his position is equally aero as Ewan's, but Alaphilippe's position is the best... But obviously both unfit for sprinting.
User avatar Logic-is-your-friend
Senior Member
 
Posts: 2,602
Joined: 07 Jun 2011 12:17

13 Jul 2019 14:25

The other moto thread is focused on safety, but some of this could be added to that thread.

I find all this type research interesting. Too often though, they look at a single factor. ie: Ewan's sprint position is aeoro (less drag) but could he produce more watts if he stood up more? Could he be faster? Its somewhat like when they started pushing TT positions: riders punched a nice hole through the air but couldn't pedal or breath as well.
jmdirt
Senior Member
 
Posts: 3,807
Joined: 06 Dec 2013 17:33

Re: AIR RESISTANCE: influence of motorbikes, bike position e

13 Jul 2019 17:24

I don't mind motorpacing. It encourages aggressive riding. If you want to be motorpaced, attack, or ride at the front.
Lance Armstrong
Member
 
Posts: 778
Joined: 10 Mar 2009 14:25

Re: AIR RESISTANCE: influence of motorbikes, bike position e

13 Jul 2019 17:42

Lance Armstrong wrote:I don't mind motorpacing. It encourages aggressive riding. If you want to be motorpaced, attack, or ride at the front.

Depending on which nationality you're from... Camera today, behind De Gendt... but in front of Alaphilippe/Pinot.
User avatar Logic-is-your-friend
Senior Member
 
Posts: 2,602
Joined: 07 Jun 2011 12:17

Re:

13 Jul 2019 17:53

Logic-is-your-friend wrote:They didn't compare both positions. Obviously because one was for sprinting and one for descending. It's possible that Froome his position is equally aero as Ewan's
Yes, they are not comparable, because not for the same scenario. Ewan all things considered is more aero than Froome, but that doesn't matter. I meant 'Position Froome is less-effective compared to 'Position Top Tube 4'

I don't sit on the top tube because of discomfort, because I go very fast on descents anyway, and obviously, do amateur stuff in which it's never going to matter which position we use. The more the vertical gain the worse I will do because I am rubbish at climbing. I guess I am 'Position Back Down 2' except slightly worse because of having my fingers on the brake levers not on the bar tops

Ewan crashing himself out without touching anyone, and he takes down 10 other riders in the middle of the bunch sprint
https://www.youtube.com/watch?v=lxjNADtngNI

Ewan clipping himself out and causing a dangerous situation, not to mention losing the sprint
https://www.youtube.com/watch?v=JsiUrYdiFS0v

He is relatively unstable, and his crashes are not totally freak accidents. There is this online article / video called "Everyone Should Be Sprinting Like Caleb Ewan" .... I disagree with that title, and think amateurs are going to crash a lot trying to imitate Ewan, because what he does is hard to imitate both in setup and skill. "Do Not Try This At Home" would be my disclaimer for his videos

All of the testing about moto-bikes is interesting and probably unprecedented, the scientists point out something important in world tour racing scenarios. The pressure wave ahead of a moto and why one would not want to be right next to them, I think that is well-known... but the drafting from so far back they prove something new
ClassicomanoLuigi
Member
 
Posts: 579
Joined: 06 Jul 2016 03:20

13 Jul 2019 18:21

There was an interesting slo mo of Ewan's back wheel skipping all over the pace during the sprint on yesterday's stage, because he has so much weight over the front of the bike.

I wonder how much that rear wheel skipping negates the obvious aero benefits he gets from his position on the bike?
Orbit501
Member
 
Posts: 935
Joined: 27 Aug 2012 11:43

Re:

13 Jul 2019 19:23

Orbit501 wrote:There was an interesting slo mo of Ewan's back wheel skipping all over the pace during the sprint on yesterday's stage, because he has so much weight over the front of the bike.

I wonder how much that rear wheel skipping negates the obvious aero benefits he gets from his position on the bike?

It was due to bumps in the road (in combination with his weight distribution). It won't be a problem in many cases.
User avatar Logic-is-your-friend
Senior Member
 
Posts: 2,602
Joined: 07 Jun 2011 12:17

13 Jul 2019 20:48

Wow you posted this today and then the allegations happen, its almost as if you knew
del1962
Veteran
 
Posts: 7,045
Joined: 16 Oct 2012 17:20

13 Jul 2019 21:21

2.6 seconds per kilometer (at 54 km/hr) is a big number, but rarely is there a perfect draft for all 60ish seconds of a kilometer for a rider to gain 2.6 seconds. A 6 second draft is egregious, and we are left with 0.26 second advantage?

Important information. Commissars should know, moto drivers should know. But impactful? Only under extreme negligent or dissonant moto drivers. Not zero, but not a cause for total reform like removing motor bikes for drones or anything.
More Strides than Rides
Senior Member
 
Posts: 2,232
Joined: 15 Mar 2011 23:52

Re:

13 Jul 2019 21:33

More Strides than Rides wrote:2.6 seconds per kilometer (at 54 km/hr) is a big number, but rarely is there a perfect draft for all 60ish seconds of a kilometer for a rider to gain 2.6 seconds. A 6 second draft is egregious, and we are left with 0.26 second advantage?

Important information. Commissars should know, moto drivers should know. But impactful? Only under extreme negligent or dissonant moto drivers. Not zero, but not a cause for total reform like removing motor bikes for drones or anything.


2.6 seconds per kilometer is at 30 meters distance from the motorbike. Nobody complains about drafting when there’s a moto a full 30 meters away (although the numbers suggest they should). 30 meters is where bikes sit for head on shots on great big Spanish motorways. If there’s a continuous head on shot on roads like these, the camera bike is a lot closer.
Zinoviev Letter
Veteran
 
Posts: 6,729
Joined: 18 Aug 2010 13:18

13 Jul 2019 21:38

Great research. It makes you wonder how much influence motors have had on famous races in the past. Maybe they should use drones to film the race?
La fatica in montagna per me è poesia (Fatigue in the mountains is poetry to me) - Marco Pantani
Van een ezel kunt ge geen koerspaard maken (You can't turn a donkey into a race horse) - Patrick Lefevere
User avatar Pantani_lives
Member
 
Posts: 1,591
Joined: 03 May 2010 13:27

Re:

13 Jul 2019 21:40

Pantani_lives wrote:Great research. It makes you wonder how much influence motors have had on famous races in the past. Maybe they should use drones to film the race?


Is using drones really feasible?
del1962
Veteran
 
Posts: 7,045
Joined: 16 Oct 2012 17:20

Re:

13 Jul 2019 21:42

More Strides than Rides wrote:2.6 seconds per kilometer (at 54 km/hr) is a big number, but rarely is there a perfect draft for all 60ish seconds of a kilometer for a rider to gain 2.6 seconds. A 6 second draft is egregious, and we are left with 0.26 second advantage?

Important information. Commissars should know, moto drivers should know. But impactful? Only under extreme negligent or dissonant moto drivers. Not zero, but not a cause for total reform like removing motor bikes for drones or anything.

I'm a big believer that it's inevitable that polluting helicopters and race rigging motorcycles should and eventually will be replaced by drones. Maybe not next year, maybe in 5 or 10, maybe 20 years. But it should and will happen. Maybe technology needs to improve a bit still, and it won't be perfect from the start, but it's inevitable.

I also don't know what math you are applying. There is 12% less air resistance riding behind a bike that is riding as far as 30 meters (!) in front of a rider. Look at the image in the opening post, of Alaphilippe's "winning ride" of last week. He's riding no more than 10 meters behind TWO motorcycles, on a straight road. According to this study, that means 23% less resistance! That's immense. You are deluded if you think that didn't win him multiple seconds per km as well as thinking that this doesn't happen often or decides races.
User avatar Logic-is-your-friend
Senior Member
 
Posts: 2,602
Joined: 07 Jun 2011 12:17

13 Jul 2019 21:54

I've been thinking about drones for cycling coverage before and in more detail again today after the topic came up again. Been looking at what's on the market currently for professional use. There are some interesting problems to solve for this to become feasible which I'd love to investigate in more detail.
Linking up with the topic of the thread, it would also be interesting to see the effects of a drone flying closely in front of a rider.
Sestriere
Member
 
Posts: 669
Joined: 24 Jun 2017 11:59

Re:

13 Jul 2019 22:04

Sestriere wrote:I've been thinking about drones for cycling coverage before and in more detail again today after the topic came up again. Been looking at what's on the market currently for professional use. There are some interesting problems to solve for this to become feasible which I'd love to investigate in more detail.
Linking up with the topic of the thread, it would also be interesting to see the effects of a drone flying closely in front of a rider.


You wouldn't need to fly closely in front of a rider. First of all, you don't even have to fly "over" the road, you can fly next to it. Camera's will be much more stable than from a bike. Less vibrations and shakes, meaning you can fly farther ahead and zoom closer (which is a problem on a bike due to vibrations). For personal use, check DJI. They have really great quality drones under 1000$ with great image quality.

del1962 wrote:
Pantani_lives wrote:Great research. It makes you wonder how much influence motors have had on famous races in the past. Maybe they should use drones to film the race?


Is using drones really feasible?

Camera drones are (just like a motorcycle) operated by two people. One pilotting the drone, one doing the camera. The main hurdles currently are the range of control and battery life. It's probably too soon yet, but technology progresses fast, especially once it hits mass production. Even 1000 dollar drones are used for professional TV reports. Image quality is actually very good, it will be more stable than shot from a motorbike. But i don't know the cost and specs of high-end drones. I know DJI has a pro camera drone (for television) for "only" +/-5000 dollars. Very stable and fast. But maybe there are even better drones for 5x that price, that have longer range and better battery. In theory, you could consider having a bus to operate the drones, riding 100 meters in front of the peloton, and swap batteries every 30 minutes, while staying close to the drone (for range). But i think it's still too soon. I guess they'll start on closed loop competitions first, and maybe start experimenting in 5 to 10 years. I 'm pretty sure they're being used on some CX races already since a few years.

But this is just my personal belief/opinion. I'm neither a drone expert, nor an aerodynamics expert.
User avatar Logic-is-your-friend
Senior Member
 
Posts: 2,602
Joined: 07 Jun 2011 12:17

Re: Re:

13 Jul 2019 22:17

Logic-is-your-friend wrote:
Sestriere wrote:I've been thinking about drones for cycling coverage before and in more detail again today after the topic came up again. Been looking at what's on the market currently for professional use. There are some interesting problems to solve for this to become feasible which I'd love to investigate in more detail.
Linking up with the topic of the thread, it would also be interesting to see the effects of a drone flying closely in front of a rider.


You wouldn't need to fly closely in front of a rider. First of all, you don't even have to fly "over" the road, you can fly next to it. Camera's will be much more stable than from a bike. Less vibrations and shakes, meaning you can fly farther ahead and zoom closer (which is a problem on a bike due to vibrations). For personal use, check DJI. They have really great quality drones under 1000$ with great image quality.



Maybe you wouldn't need to fly very closely in front of the riders due to said benefits. However, drones would also offer new opportunities for great action shots due to possible proximity to riders. If you wanted to use this potential it would be interesting to learn something about aerodynamics in that regard as well.
Also, I believe, in some cases you would actually have to fly oer the road, for example when the road is completely/largely covered and sheltered by trees or buildings ot other topographic features.

Yep, I ended up on DJI's website as well.
Sestriere
Member
 
Posts: 669
Joined: 24 Jun 2017 11:59

13 Jul 2019 22:21

Sure, but you can adapt to circumstances. You can't jump onto the pavement or ride on rooftops with a motorcycle. But flying a drone close to a rider (in line of sight) is probably not preferable for safety reasons.

PS: don't forget that in many countries there are strict regulations now for drones. Depending on your country, you might need a special license. Just in case you are considering buying one.
User avatar Logic-is-your-friend
Senior Member
 
Posts: 2,602
Joined: 07 Jun 2011 12:17

Re:

16 Jul 2019 21:35

ClassicomanoLuigi wrote:aero matters a lot because power requirement to overcome air resistance increases exponentially with speed.


The relationship between speed and power output is a cubic equation (a mathematical power function), and is *not* an exponential equation. Exponential implies something vastly different to a power law.
User avatar Alex Simmons/RST
Senior Member
 
Posts: 2,287
Joined: 10 Mar 2009 23:47
Location: Australia

Next

Return to Professional road racing

Who is online

Users browsing this forum: Alexandre B., alspacka, Asero831, Bushman, Crevaison, emilos, Flamin, Google Adsense [Bot], Hugo Koblet, IndianCyclist, Jagartrott, Josh Homme, LaFlorecita, lartiste, Logic-is-your-friend, Panda Claws, Sestriere, topcat, TourOfSardinia, wansteadimp, Yingge and 132 guests

Back to top