CDA - AERODYNAMICS - DRAG: influence of motorbikes, bike position etc

[Logic-is-your-friend]

Drones at CX races (and MTB):
Those I've seen have, apart from pre-race course previews, been cable cams rather than drones - i.e. cameras suspended on a system of overhead cables, cable car fashion. The give away is that you get the same moving overhead shots every lap, and occasionally you can see the shadows of the system..

Today you could hear the drones during the actual race.

 

[Logic-is-your-friend]

Found this tweet from professor Blocken:

https://twitter.com/x/status/1338384609466339330

View: https://twitter.com/realbertblocken/status/1338384609466339330


For those who wish to read in depth reports:

Impact of a motorcycle on cyclist aerodynamic drag in parallel and staggered arrangements - Sports Engineering

Cycling races contain a multitude of motorcycles for various activities including television broadcasting. During parts of the race, these motorcycles can ride in close proximity of cyclists. Earlier studies focused on the impact of a nearby motorcycle on cyclist drag for in-line arrangements...

link.springer.com

Impact of wheel rotation on the aerodynamic drag of a time trial cyclist - Sports Engineering

Aerodynamic drag is the main resistive force in cycling at high speeds and on flat terrain. In wind tunnel tests or computational fluid dynamics simulations, the aerodynamic drag of cycling wheels is often investigated isolated from the rest of the bicycle, and sometimes in static rather than...

link.springer.com

Cyclist aerodynamics through time: Better, faster, stronger

The last decades have seen an increasing interest in cycling aerodynamics, with the design of more aerodynamic bicycles and wearable equipment such as…

www.sciencedirect.com

Aerodynamic benefits for a cyclist by drafting behind a motorcycle - Sports Engineering

Motorcycles are present in cycling races for reasons including television broadcasting. During parts of the race, these motorcycles ride in front of individual or groups of cyclists. Concerns have been expressed in the professional cycling community that these motorcycles can provide aerodynamic...

link.springer.com

CFD analysis of an exceptional cyclist sprint position - Sports Engineering

A few riders have adopted a rather exceptional and more aerodynamic sprint position where the torso is held low and nearly horizontal and close to the handle bar to reduce the frontal area. The question arises how much aerodynamic benefit can be gained by such a position. This paper presents an...

link.springer.com

The impact of arm-crank position on the drag of a paralympic hand-cyclist

The aerodynamic features associated with the rotation of a cyclist’s legs have long been a research topic for sport scientists and engineers, with studies in recent years shedding new light on the ...

www.tandfonline.com

Aerodynamic analysis of different cyclist hill descent positions

Different professional cyclists use very different hill descent positions, which indicates that prior to the present study, there was no consensus on …

www.sciencedirect.com

Aerodynamic benefit for a cyclist by a following motorcycle

In recent years, many accidents have occurred between cyclists and in-race motorcycles, even yielding fatal injuries. The accidents and the potential …

www.sciencedirect.com

A following car influences cyclist drag: CFD simulations and wind tunnel measurements

It is well-known in elite cycling that a cyclist riding behind a car experiences a substantial reduction in aerodynamic resistance or drag. However, t…

www.sciencedirect.com

http://www.urbanphysics.net/JBME_TD_BB_EK_PH_PV_BN_JC_4_Cyclists___Preprint.pdf

CFD simulations of the aerodynamic drag of two drafting cyclists

The aerodynamic drag of two drafting cyclists in upright position (UP), dropped position (DP) and time-trial position (TTP) is analysed by Computation…

www.sciencedirect.com

Computational fluid dynamics analysis of drag and convective heat transfer of individual body segments for different cyclist positions

This study aims at investigating drag and convective heat transfer for cyclists at a high spatial resolution. Such an increased spatial resolution, wh…

www.sciencedirect.com

Aerodynamic study of different cyclist positions: CFD analysis and full-scale wind-tunnel tests

Three different cyclist positions were evaluated with Computational Fluid Dynamics (CFD) and wind-tunnel experiments were used to provide reliable dat…

www.sciencedirect.com

Computational fluid dynamics analysis of cyclist aerodynamics: Performance of different turbulence-modelling and boundary-layer modelling approaches

This study aims at assessing the accuracy of computational fluid dynamics (CFD) for applications in sports aerodynamics, for example for drag predicti…

www.sciencedirect.com

Tijdswinst voor wielrenner achter motor veel groter dan gedacht

In wielerwedstrijden rijden veel motoren mee, bijvoorbeeld met cameramannen. Renners in de windluwte achter motoren kunnen flinke tijdswinst behalen. Voor het eerst is wetenschappelijk onderzocht hoe groot dit voordeel precies is – en het blijkt nog veel groter dan gedacht.

nieuws.kuleuven.be

 

[SHAD0W93]

That’s a lot of work put into it.


And I’m not going to lie, I completely forgot this thread existed and thought it was a spam bot with the capital letters till I saw the op was Logic

 

[Logic-is-your-friend]

PS: in light of the discussion regarding replacing camera motorbikes with drones...

UCI has allowed drones to be used but the organizer simply has to have permits and documents in order. As i said earlier, cyclocross, mountainbike, TT's etc could be testing grounds.

View: https://www.youtube.com/watch?v=jy0WBD0Acj0&t=105s

 

[IndianCyclist]

Found this tweet from professor Blocken:

https://twitter.com/x/status/1338384609466339330

View: https://twitter.com/realbertblocken/status/1338384609466339330

Nice collection of papers. However i find the drag reduction stated are probably too high. In the paper itself it is agreed that the spread of the drag reduction claimed by various citations is high. Look at the 90% of reduction for the peloton. Imaging a peloton bus. Hire a couple of pro riders as drivers at the front of the bus to drive at 400 w@ 50 kph. In the middle a person only has to spend 10% rolling friction and 10% due to drag which is equal to 80 w. All of these are not reflected in real life but the numbers can be taken in relative context though. For example if a team is leading at the front, then the team leader should be at 4th position or futher back to save energy.

 

[ice&fire]

According to that figure from Prof Blocken a moto 20m and 10m ahead of the rider produces more drag reduction than a car at similar distance. It's weird that measurements and simulations for these two types of vehicles have not been done for the same distances.

 

[Logic-is-your-friend]

Nice collection of papers. However i find the drag reduction stated are probably too high. In the paper itself it is agreed that the spread of the drag reduction claimed by various citations is high. Look at the 90% of reduction for the peloton. Imaging a peloton bus. Hire a couple of pro riders as drivers at the front of the bus to drive at 400 w@ 50 kph. In the middle a person only has to spend 10% rolling friction and 10% due to drag which is equal to 80 w. All of these are not reflected in real life but the numbers can be taken in relative context though. For example if a team is leading at the front, then the team leader should be at 4th position or futher back to save energy.

It's all in a best case scenario. No wind interference, no moving up/down in the peloton, no fighting for position before a hill or a sharp turn, no closing a gap due to road furniture...

According to that figure from Prof Blocken a moto 20m and 10m ahead of the rider produces more drag reduction than a car at similar distance. It's weird that measurements and simulations for these two types of vehicles have not been done for the same distances.

I also noticed that and wonder. Supposedly the car has more impact than the motorbike at shorter distance, but less at longer distance, if i'm reading this correctly.

 

[lemon cheese cake]

PS: in light of the discussion regarding replacing camera motorbikes with drones...

UCI has allowed drones to be used but the organizer simply has to have permits and documents in order. As i said earlier, cyclocross, mountainbike, TT's etc could be testing grounds.

View: https://www.youtube.com/watch?v=jy0WBD0Acj0&t=105s

I think drones were being used in the algarve TT, though the footage from it wasn't as great or clear as what we saw in the Superprestige Gavere.

 

[Logic-is-your-friend]

I think drones were being used in the algarve TT, though the footage from it wasn't as great or clear as what we saw in the Superprestige Gavere.

They also used drone footage during the 2020 Giro TT. Always the same stretch obviously.

 

[Izzyeviel]

I saw the front page article where they mentioned the riders being followed with cars stacked with bikes - can someone explain (simply) how that would help the rider?

 

[Logic-is-your-friend]

I saw the front page article where they mentioned the riders being followed with cars stacked with bikes - can someone explain (simply) how that would help the rider?

It basically pushes a cushion of air into the back of the rider, ''breaking'' the air in front of the rider in a way it would otherwise not do.

https://twitter.com/x/status/1559863241408499713

View: https://twitter.com/ValaAfshar/status/1559863241408499713

 

[Logic-is-your-friend]

Drones are being used in CX more and more, and now it looks like F1 is warming up to the idea. Let's hope this technology keeps making strides so that we can see drones completely replace camerabikes in cycling before i die. Obviously it's easier to implement this on a closed circuit like CX and F1, but it is a way to test and improve equipment and gain crucial experience.

View: https://www.youtube.com/watch?v=9pEqyr_uT-k