Calculating Frontal Area and Drag Co-efficient

[Jeffrey Ritter]

A diamond frame rider turned me onto gribble-a site that allows you to better understand the power required to achieve certain speeds. The link takes you to a calculator that will input variables, including frontal area and drag co-efficient.

I suspect these are only determined in a wind tunnel, but does anyone have any sense of the manner these are calculated for our bikes, rather than just the religion of believing we are more aero. Would be great to have the science and the religion.

https://www.gribble.org/cycling/power_v_speed.html

If I input my body weight (185) and Silvio weight (24.7) and reverse engineer to the power and speed I generate in the Cruzbike TT series on a flat road, I get a value for A of 2.875 and Drag Coefficient of 0.63.

 

[trplay]

Cruzbike published their wind tunnel data for Jim. Maria, Larry. It's somewhere in the history.

 

[LarryOz]

You also look up the Chung method which take many factors into account from actual ride data and spits out a number for you
In reality - the harder you push the faster you go - I just crack myself up sometimes!!! sorry couldn't help myself
The number is really only worth something to compare yourself from one setup to another to help determine how much faster or slower you would be - wind tunnel is the best and most expensive place to find that out.

 

[Jeffrey Ritter]

Larry, you crack ME up too. Love it. And the setup options are exactly where I am headed. Have to have something to play with!

Best,
J

 

[Andrew Wilson]

https://cruzbike.com/blogs/blog/cruzbike-at-the-a2-wind-tunnel

 

[Mathew Fy]

@Jeffrey Ritter
I remember you thinking of switching to a V20 with a Thor seat (due to your c-spine fusion.) Did anything come of that? I’m curious if that could make you faster.

 

[Kufman]

It is interesting to compare the CB data to the somewhat theoretical data on this page for the various downhill positions for upright bikers. For the most part, it appears that Vendetta riders can expect to have better aero than just about any of the upright downhill positions.

https://www.sciencedirect.com/scien...ll-scale frontal areas,“Back down 1” position.