These pics might be of interest to some of you lot here. If nothing else, they let you visualise the flow of air over the rider quite nicely!
Airspeed 11.1m/s (about 25mph) and the frame is modelled on a Planet X Stealth.
One of the things that jumps out at me is that the bottom of the rear wheel sees some very clean airflow.
Interesting. What application(s) are you using for this modeling?
I’ve just done my dissertation on the praying mantis position.
As I nearly had the model I thought that I may as well do a little bit of extra work and publish the results online so that subsequent debates could be more informed.
It works for some people but not for others
More specifically, it seems to work in some cases where the rider has widers hips and thin arms. My reccomendation is that people use a 5-10° angle as this worked for every case I modelled apart from some top heavy triathletes. I’ll release the paper in about a month once it’s been checked by my assesors.
Drag reduction of about 2% measured via these 3 methods; frontal area calcs, rolling down a hill and also via CFD.
Drag reduction of about 2% measured via these 3 methods; frontal area calcs, rolling down a hill and also via CFD.
What was your precision on rolling down a hill compared to frontal area and CFD?
What was your precision on rolling down a hill compared to frontal area and CFD?
Quite large! The prblem was that the speed was high so time reductions were small for slightly higher speeds. For more info on this, you’ll have to wait until my report comes out I’m afriad; it’s a long answer!
So the next big thing will be . . . . . Butt fairings?
Cool images, thanks for posting!
Interesting for comparison to recent post by Dev about elbow spacing. Looks like more space between elbows, and between hands, might help open up the flow around the torso. Any comments/insights on elbow and hand spacing based on your research?
I only modelled stright ahead forearms but the biggest drag reduction seemed toi occur as the elbows went from outside to inside the knees. Moving the elbows in so that they were touching reduced the drag by the same amount again.
Spacing the elbows wide apart seemed to make the air flow down between them. In the mantis position, the downwards airflow was in front of the forearms instead.
As the arms were bought closer together, the mantis position seemed to be less beneficial.
So the next big thing will be . . . . . Butt fairings?
They were used by track cyclists pursuing timed records back in the 1920s/30s, and more recently Corima marketed a saddle in the 1980s that incorporated a back to push against/streamline your body.
I expected more turbulant air immediately following the bottom bracket. It’s certainly not smooth, but I expected it to be a total mess.
And I’m going to second a new butt fairing…
So the next big thing will be . . . . . Butt fairings?
They were used by track cyclists pursuing timed records back in the 1920s/30s, and more recently Corima marketed a saddle in the 1980s that incorporated a back to push against/streamline your body.
Do you mean like this? 
More specifically, it seems to work in some cases where the rider has widers hips and thin arms.
FWIW, up-angled forearms didn’t work for my wife.
My reccomendation is that people use a 5-10° angle
That’s generally consistent with John Cobb’s rule-of-thumb, not to mention numerous other tests/results. For example, after much experimentation Hooker settled on a fixed aero bar angle of +15 deg, whereas the original one-piece VisionTech bars were available in different versions ranging from level to +15 deg. IOW, there’s a lot of data out there pointing at a slight up-tilt being, on average, most aerodynamic.
These pics might be of interest to some of you lot here. If nothing else, they let you visualise the flow of air over the rider quite nicely!
Airspeed 11.1m/s (about 25mph) and the frame is modelled on a Planet X Stealth.
One of the things that jumps out at me is that the bottom of the rear wheel sees some very clean airflow.
Oh yeah…his seat’s too high
So the next big thing will be . . . . . Butt fairings?
They were used by track cyclists pursuing timed records back in the 1920s/30s, and more recently Corima marketed a saddle in the 1980s that incorporated a back to push against/streamline your body.
Do you mean like this?
Thanks! I was searching for a pic like that, but couldn’t find one.
On a semi-related note: who else here remembers the Ron Skarin-powered Teledyne Titan streamliner? (Man, I’m really dating myself…
These pics might be of interest to some of you lot here. If nothing else, they let you visualise the flow of air over the rider quite nicely!
Airspeed 11.1m/s (about 25mph) and the frame is modelled on a Planet X Stealth.
One of the things that jumps out at me is that the bottom of the rear wheel sees some very clean airflow.
Oh yeah…his seat’s too high
But seriously: the cranks appear awfully short, or really I should say, the foot seems quite high off the ground (in the 2nd pic) despite the knee angle. I’m wondering if perhaps that explains the seemingly quite clean air around the bottom part of the rear wheel.
Zebra,
Were these CFD studies only looking at zero yaw? Obviously, the roll-down tests are going to be somewhat limited to that, so I was just curious about the CFD analysis.
Cool visuals, BTW.
So the next big thing will be . . . . . Butt fairings?
They were used by track cyclists pursuing timed records back in the 1920s/30s, and more recently Corima marketed a saddle in the 1980s that incorporated a back to push against/streamline your body.
Do you mean like this?
Thanks! I was searching for a pic like that, but couldn’t find one.
On a semi-related note: who else here remembers the Ron Skarin-powered Teledyne Titan streamliner? (Man, I’m really dating myself…
The funny thing is that the only reason I knew how to find it was that I happened to be thumbing through “Cycling Science” the other night looking for something else and I had run across that pic. When you mentioned it, I recalled that the rider’s name was “Oscar Egg”. That made the search pretty simple
I don’t remember anything about the Teledyne Titan. You must be older than me…
I recalled that the rider’s name was “Oscar Egg”.
Unlike, e.g., Sosenka, Egg wasn’t just a one-hit wonder:
http://en.wikipedia.org/wiki/Oscar_Egg
I don’t remember anything about the Teledyne Titan.
http://www.classicrendezvous.com/...e/Teledyne_titan.htm
Ron Skarin went 51.31 km in 1 h on a fully-enclosed version back in 1979.
You must be older than me…
I may be older, but I’m still faster.