New cal ride

[Wobblydrow]

Hi

I have changed my PP location so wanted to do a new set of cal rides across my three bikes so deleted profiles by reset unit in Isaac.

Set up first bike, cal ride worked well. Downloaded details and then set second bike as active profile, but as I have seen in the past the cal ride didn't go the same.

What is the solution...

1) the green goes out correctly after finding sensors, solid yellow then appears not the green/red alternating even after a riding a distance

2) start the test by clicking the unit, light stays solid yellow

2) When 50W is reached I dont get the solid red light, the count up continues to exceed 50W on counter rather than stick at 50W, and dont get the finishing yellow light.

3)turn round and counts to 100 as then gives power, but when download file, no ibr file is created and wind scale is 1.00

4)The 0-100 O&B is about 40% shorter in distance than when the "correct" cal is done, I have repeated this many times.

I have tried 12 second reset and try again but no success, I can't seem to get a ibr cal ride file generated following first bike. Please help

[Velocomp]

Hmm...please email technicalsupport@velocomp.com for next steps.

[Wobblydrow]

Thanks John tech support assisted and fixed the issue, they said after sensor pairing to ride for 10-15s to get red/green flash, not press the button to get yellow light and then red/green as per what the instructions say. Once did that everything worked.

If i have two road bikes of the same Crr, the wind scale on one was 1.05 and the other 1.3, but in each case the aero/wind scale divided to exacty 3.23, does that mean if this ratio is consistent across bike with same CRR and weight, then the unit is correctly calibrated? Can i assume the two numbers ratio out in the way the unit calcultes power so as long as the ratio is maintained its ok?

During a ride do these value change as per the unit continually checking the mounting angle, or are they locked in at the time of calibration?

[Velocomp]

If i have two road bikes of the same Crr, the wind scale on one was 1.05 and the other 1.3, but in each case the aero/wind scale divided to exacty 3.23, does that mean if this ratio is consistent across bike with same CRR and weight, then the unit is correctly calibrated? Can i assume the two numbers ratio out in the way the unit calcultes power so as long as the ratio is maintained its ok?

During a ride do these value change as per the unit continually checking the mounting angle, or are they locked in at the time of calibration?

The details of the relationship between aero and fric are a bit of a mystery...even to me! Those values are determined during the cal ride, and remain fixed after the cal ride.

[lorduintah]

I would think that as the angle of attack of the orifice on the PP is not exactly the same for each bike (unless there is a lot of serendipity) that these factors would vary (wind scale and aero). The same ratio is also not really surprising if it is the same PP as the sensor inside the PP detecting air flow is the same and so its sensitivity should overall be a constant.
As far as the friction factor, John informed me that that factor is related to the tilt angle of the PP and you will or may notice that value moves around too with each bike mount being different.

[Wobblydrow]

Interesting, I have 2 bikes both with minus 0.7 degree tilt yet different aero/friction value (with some crr etc.), so must have another variable in how it's calculated.

I guess my ultimate aim was to understand what calibration actually does relative to the numbers produced and understand for comparable bikes with same variables, why the numbers can be different. Being a scientist these things interest my logical mind

My only conclusion can be if a cal ride is done in low wind conditions the wind scale variable is low, which then must mean the aero is low to maintain the same ratio. I am guessing the wind scale and tilt are the primary numbers established in a cal ride, and then the user inputted variables and speed are used to produce a new fric value, and all together then give a power. Though I could be wrong

[lorduintah]

Velocomp/John are likely to want much of the math to remain their intellectual property.

Cal rides in low wind allow the aero portion to use the bike speed as much as anything to estimate the wind factor. With a high wind, the bike speed plays less of a contribution and thus I suspect harder to nail down the sensor calibration.

If both bikes have about the same tilt - how different are the friction values? But it would not surprise me that there is more to this one with an accelerometer or other force measurements playing roles. Friction has contributions from the rolling wheels, interaction with the road surface (maybe more than just Crr), body cross-section, gravity, rider and bike weights and so on. Then you have that little Machine Constant (Cm) hanging around. Are you holding Crr constant?

Based on many of the posts, the old standard was to get your bike up to more than 20 MPH and coast down. I suspect some newer physics came into play as the algorithms have evolved along with just the electronics and design. No more coast downs. And the tilt is re-calibrated in the first few minutes of your rides. And has been noted - if the mount is not stable and solid, power calculations go haywire.

If I do new calibrations at the same location, the factors in the profile screen are nearly identical and I find that I no longer run the "Check Calibration" option, but may at least look at the other Analyze options -

[Wobblydrow]

One bike was 1.05 and the other 1.3 wind scale, associated aero/friction the same proportional difference. . Everything else the same (both road bike of similar weight, 25mm tyres at same pressure etc)