Frequently asked questions and answers
Your bike needs a powermeter, speedometer and optionally a Notio aero device. Run123 uses the 4Hz sensor measurements from the Notio aero device to compute your CdA & Crr.
If you don't have a Notio, you can instead use a FIT or TCX file from your bike computer. These files record data (e.g. power, velocity, elevation) at 1Hz but are missing some needed data (e.g. total mass, assumed Crr, density, airspeed) which you'll have to manually enter. I recommend a magnetic sensor speedometer since accelerometer-sensor speedometers report noisier velocities.
The Notio CdA algorithm is extremely sensitive to velocity; slower speeds result in giant increases in CdA. If you compare the Notio Virtual Elevation (VE) with measured elevation, you'll find that the VE is tens of meters higher = Notio CdA is far too low. So the Notio CdA bounces between being too low and too high. So Notio results vary a lot and are not accurate. Argh!
These problems irritated me so much that I developed the AeroStar algorithms to compute an accurate CdA. The AeroStar app plots all CdAs and VEs so you can easily compare them. Note that the AeroStar VE is usually spot on with measured elevation.
Run123 analyzes 3 test runs recorded on the same path.
A Competitive can hold their position and consistently generate the same power. This results in very consistent CdA graphs making it easy to detect subtle changes. This makes it easy to do ABABAB testing of positions or equipment. Expect a CdA accuracy of about 0.002
A Weekend rider is not as strong and tires easily and their position is always changing slightly. This results in a CdA curve with appreciable differences for a 'constant' test ride. Expect a CdA accuracy of about 0.005.
A TT bike with aerobars 'locks' in the position of the rider much more than a road bike. On a road bike the rider can't really 'lock' the elbow angles leading to different aero drag resulting in a 'noiser' CdA curve. A road bike with aero bars will have more consistent CdA results than one without.
The Run123 algorithms are patent pending. Run123 uses an energy method similar to Virtual Elevation (VE), but with lots more math.
A consistent position will give you a 'flat' CdA curve with low variation. If you stop and switch equipment (e.g. helmets) and ride the same laps again, then you can compare the CdA for all laps. If the CdA is consistently lower than you've identified more Aero equipment.
Note: this is much easier if you are a competitive or Pro rider since the resolution of your CdA curve may be ~0.001. I recommend comparing equipment or positions with AB-AB-AB testing on a 400m loop using 3 sets of 6 laps of A followed by 6 laps of B (12 laps per set). The total test will be 12+12+12=36 laps. Note that at 12 m/s (43 km/h) a CdA change of 0.001 is 1W. Yes it's a lot of work to identify repeatable 1W changes!
The Run123 algorithms run on flat or hilly terrain, zero, constant or varying power.
Braking is a dissipative force that is not modeled, so the Run123 algorithm thinks your aero drag resistance just got lots bigger! Sometimes braking shows up on the Virtual Power validation graph as negative power spikes. 'Negative Power' -- what's that you ask? Simple, pedaling is Positive Power and braking is Negative Power. If you want a smooth flat CdA curve than avoid braking and keep the same position.
Most graphs have a 'Camera' button to add the current graph to a report list. On the 'Report' page select each item and add annotations as html-formatted text. Press the checkmark to save. When done with all items press the 'PDF' button to save the report as a PDF file.
On the 'Load' page there is an 'Export' button which saves your ride data in a JSON file.