Profile range guidelines - still good?

[dtrousdale]

I got the following profile range guidelines from an earlier post. Are these still good for a Newton+?

CdA

TT: 0.2 to 0.33
Hoods: 0.28 to 0.45
Drops: 0.26 to 0.42

Crr:

0.002 to 0.008

The smaller the number, the better your tires and the smoother the pavement. Towards the high end, you're on chip seal or even dirt

Wind Scaling Factor

Stem: 0.5 to 1.5

Handlebars: 1.3 to 4.5

Riding tilt:

0.0% to -1.2%

(riding tilt should never be positive)

Aero:

0.15 to 2.0

Aero depends on your CdA and your wind scaling factor; lower numbers would be for stem mount locations and TT ride positions

Fric

3.0 to 17

Fric depends on Crr, riding tilt, and total weight. Bigger numbers are caused by a combination of large negative riding tilt and large rider weight

[Russ]

Lowest CRR listed in this article as tested was .0038

http://rouesartisanales.over-blog.com/a ... 03651.html

Russ

[racerfern]

I got the following profile range guidelines from an earlier post. Are these still good for a Newton+?

The basic calculations that determine your power have not changed since the Gen1 because the laws of physics have not changed.

What has changed is the software that now gracefully handles all the values thrown at it. The sensors have changed and are now more accurate and the better processors can handle more data. However, the basic tenets of how much power is required to overcome existing conditions has not changed.

So... wind scaling will still vary based on the location of the unit. Newton handles side winds much better but the basic function remains constant. The profile numbers from a previous generation unit will transfer over to a Newton; you just need to do a cal ride to establish your wind scaling.

So... all the numbers you posted are applicable to Newtons also.

[JPCH]

Could you provide a definition of these parameters (or a pointer) ?
I would also be interested in an description of the calibration ride physical principles (and corresponding equations).
WIthout understanding what's going on, the calibration process is always stressfull.

[Zoltan]

I got the following profile range guidelines from an earlier post. Are these still good for a Newton+?

CdA

TT: 0.2 to 0.33
Hoods: 0.28 to 0.45
Drops: 0.26 to 0.42

Crr:

0.002 to 0.008

The smaller the number, the better your tires and the smoother the pavement. Towards the high end, you're on chip seal or even dirt

Wind Scaling Factor

Stem: 0.5 to 1.5

Handlebars: 1.3 to 4.5

Riding tilt:

0.0% to -1.2%

(riding tilt should never be positive)

Aero:

0.15 to 2.0

Aero depends on your CdA and your wind scaling factor; lower numbers would be for stem mount locations and TT ride positions

Fric

3.0 to 17

Fric depends on Crr, riding tilt, and total weight. Bigger numbers are caused by a combination of large negative riding tilt and large rider weight

1) I suppose your comment about Crr is true when using a road bike with tires of 20-23mm or so. If you have a trekking bike or MTB, your Crr can be over 0.008 even on some asphalt of bad quality.

2) Fric seems to be not just the friction force itself, in fact, it may be used to incorporate the quasi gradient (or gravitational) force of ride tilt into the friction force, so it likely equals to TotalWeight*9.80665*(Crr*Cos(ArcSin(RidingTilt))-RidingTilt). Cos(Arcsin(RidingTilt)) can be omitted, its effect is tiny.

3) Aero equals to WindScaling*CdA without any doubt, BUT...

4) ...Wind Scaling is the most exciting parameter, which cannot be so easily reverse engineered using the simple relationships of physics.

5) "Aero depends on your CdA and your wind scaling factor; lower numbers would be for stem mount locations and TT ride positions"
and maybe for being a shorty, because CdA=frontal area * Cd and although TT ride positions help to decrease both area and Cd, being short helps to keep area low even in hood or upright position.