Thread by @AliRouse16, I decided to start a little series explaining some aero concepts around [...]

I decided to start a little series explaining some aero concepts around bike racing with a CFD app.

Initial focus on rider in 'Tuck' behind the screen. Contour is velocity. Note the low velocity turbulent region behind the screen and riders helmet. #MotoAero #WindTunnelmovies

Small holes at the front of the screen are common place in Moto GP aswell as the TT.

These introduces higher energy air behind the screen increasing the local pressure, reducing turbulence on the helmet and can also helps feed air over the helmet. #MotoAero #WindTunnelMovies

Here are some comparison shots with and without the 'Screen Bleeds' and some examples on race bikes

#MotoAero #WindTunnelMovies

And for old times sake here are some screen bleeds I was responsible for myself, @Gary_Johnson69 TT 2014 & @bobendsneyder Mugello 2018

#MotoAero
#WindTunnelMovies

Here's a comparison of with and without helmet spoiler aswell as some examples.

Note with a large gap between the leathers and helmet (even with spoiler) there is still a significant low velocity region behind the helmet and above the riders back.

Moving downstream to the 'Speed Hump'

Around since the 90's this helps fill the void behind the riders head. This removes a low pressure region behind the rider helping reduce turbulence felt on the body as well as reducing drag.

#MotoAero
#WindTunnelMovies

Comparison of with and without hump.

These items have significant interaction and should ideally be developed together in combination to the rider and bike.

#MotoAero
#WindTunnelMovies

Hump Wings!

A concept debuted by Aprillia but never raced, aero profiles above the hump to direct flow down behind the rider. The aim again is to fill the low pressure region behind the rider to reduce overall drag, despite this producing a little.

#MotoAero
#WindTunnelMovies

Some pictures from the Aprillia 'Hump Wing' test. Only tested never raced, possibly legality or homologation reasons.

This would most likely have gone through some wind tunnel/CFD testing before this stage and must have showed some promise.

#MotoAero
#WindTunnelMovies

Comparison with and without the wings appears to shows improvement in attachment of flow over the helmet and onto the back of the rider.

Apologies for poor quality aerofoil profiles, it's hard to draw with a fingertip!

#MotoAero
#WindTunnelMovies

Next up, body positioning!

A huge factor is reducing the low pressure region behind the rider, the less extreme the taper behind the riders helmet the better usually so a long flat back is desired. This is where taller riders can have an advantage!

#MotoAero
#WindTunnelMovies

Comparing shorter and longer flatter backs shows reduced 'stress' over the helmet and down the back of the latter. This will result in less likelihood of separation and reduced drag in the latter.

#MotoAero
#WindTunnelMovies

Moving the riders bum back on the seat and even multi height seat foams to raise the strait line seat height are methods of achieving the optimum back height/taper and are tailored to each rider individually

#MotoAero
#WindTunnelMovies

A final comparison of our 'Baseline' and more 'optimised' cases show significant improvement in quality of airflow around the cockpit region. Roughly 25 years of aero developments.

Any questions or other areas you would be interested in let me know.

#MotoAero
#WindTunnelMovies

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