4 cal rides with 4 different results

[GWPOS]

Ok, I wanted to see if I get any consistency in my cal rides with coast downs. I did 4 of them, but the first one I did there was a slight breeze so maybe some of the profile numbers are off??? The rest were done in exactly the same place and the same procedure. I acclimated the IBike by riding around for 5-10 min., did the tilt cal, wind cal., cal ride, then coast downs with no wind on the last 3 attempts. Can someone please help me figure out which profile is the one I should be using in my IBike. After these attempts I am done with the cal rides. Like I said i thought I would do multiple ones, thinking I would see consistent results but they all seem different.

100502_cal_data.ibcd4m

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100506_cal_data.ibcd4m

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100507_cal_data.ibcd4m

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[GWPOS]

Ok here is my last one. I guess we can only do three at a time.

100507_cal_data.ibcd4m2.ibcd4m

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[Velocomp]

The three cal rides you did on the same stretch of road (May 6 and 7) are pleasingly consistent.

The data from your 5/2 ride was on a different stretch of road and was done in a tailwind (see previous post) so I did not use it.

The 2 mile Cal Ride is designed to provide a reasonable compromise between accuracy and convenience. Originally we specified a 4 mile cal ride (more data is better) but later-on we shortened the length the ride to decrease the amount of time needed to complete the setup process.

Especially when doing shorter cal rides, it is important to hold Crr fixed, and use the data to measure CdA.

I've held your Crr fixed at 0.004 and determined the CdA from each of your cal rides and associated coast downs:

May 6 CdA: .374 WSF: .674 Ride Tilt: -0.6%
May 7 AM CdA: .351 WSF: .698 Ride Tilt: -0.4%
May 7 PM CdA: .363 WSF: .643 Ride Tilt: -0.6%

Note that each of these cal rides were of different lengths. The 5/7 AM ride had a slightly longer Cal Ride (3.2 miles), but the 5/7 PM cal ride and coast downs were the only one conducted in calm winds (the May 6 cal ride was calm except at the end, where there appeared to be wind gusts).

The Cal Ride length is critical when trying to get the last bit of accuracy out of the iBike. So, the May 7 AM ride is the winner, by a hair.

If you want the ultimate accuracy, wait for a calm wind day, do a 4 mile cal ride, then coast downs afterwards.

That said, I would just leave your current profile as-is, and just ride the bike. You won't get better by more calibrations, but you WILL get better by leaving your profile alone and improving your power output over time.

[GWPOS]

Thanks John. I guess I am OCD right now. I noticed with the profile I am using( which is from the day I had the tail wind) that my efforts are harder than before, so I figured maybe the tail winds affected the cal ride which in turn caused my profile to be off enough to give me lower power numbers by about 20-25 watts. I am just guessing. I will do what you said and just ride for now and retest to get a current FTP with my new profile. Later I will do an 4 mile one just to compare. Again thanks

Comment on your changes. Isn't a crr of.004 pretty low??

Clint