Bad calc data?

[Roubaixalltheway]

I seem to be having trouble getting good calculation ride data. My fric number is 14+!

Here are my conditions:
Bike: 2007 Roubaix with regular handlebars, Roval wheels and Continental Attack/Force tires. The calc ride was done in my neighborhood on concrete roads. I have attached my ride data if that helps.

Aero: 0.100
Fric:14.661
Wind Scaling: 0.767
Ride tilt: -0.4
CdA: 0.130
Crr: 0.0133

Thoughts?
Thanks George

[lorduintah]

The only thing bad about this is you have used a Crr from the iBike - that seems to have been in the iBike as a default or the last value.

Either use 0.0055 as a fixed value or the Crr from letting it vary (you will get 0.0061) - These lead to very realistic aero values and friction. And much more in line with what you expect from the wheels and tires you have.

If you want to do a little better - I would ride longer for the cal ride (6 miles or more total) and do maybe even 10 coast downs.

Tom

[Roubaixalltheway]

Thanks Tom for the help, I've made the change and will give it a test on my ride tomorrow.

Question, how do I do a longer cal ride, being it tells you to go back after 1 mile?

Thanks, George

[lorduintah]

George -

As long as you do not let your speed fall to 8 mph, you can continue riding the "out" portion of the ride. When you slow down that much that your speed falls to 8 mph or lower, the iBike assumes you are now going "back." The screen will continue to tell you to turn around, but that is all that is going on there; the recording of the necessary day will continue.

You might want to verify on your cal ride and coast downs that you have the record interval set to 1 sec, also. The overall performance of the calibration seems to run better.

Tom

[Roubaixalltheway]

Thanks Tom, I'll try all of those suggestions as I did not have my recording set 1 sec.

I think I am still way off on my profile. I did a 60+ mile ride with 2400' of climb with an average of 17.5 mph and only averaged 96 watts. Seems kind of low. I attached my modified profile and the ride date if you or anybody else can point out what I have done wrong.

Thanks, George

[lorduintah]

I adjusted your profile - you did not update the profile to the change for the adjusted Crr to 0.0061. Additionally, CdA is way low and again this is changed from the cal data as the Crr is allowed to vary. I then also modified the wind scaling by taking your average ride speed and wind speed. Took the ratio and squared that. Multiplied the wind scaling by this while keeping the newer CdA constant - thus Aero changed. This was because the average bike speed and the average wind speed were not equal. This may be an over correction, but can be further corrected if you do rides out and retracing the return - you should have averaged out the wind effects by using the same path - and no significant weather conditions have intervened.

This leads to an average watts of >160 for your ride.

You will have to import this profile - from the edit profile menu interface...

Tom

[Velocomp]

The answer is in your data.

In your ride file your CdA drag coefficient is way too low: it's 0.131. This is because, somehow, your default Crr was set way too high, to 0.0133. This is shown in the "Setting in iBike" option in the Profiles/Download Coast-Downs and Cal Ride" option. See image.

The good news is that you have coast downs; by selecting the "Crr adjusted" feature you can see what your 5 coast downs measured. Based on your coast downs, your correct CdA is 0.38 (very reasonable) and your Crr is 0.0061, reasonable if your tire pressure is a bit low.

If you apply the corrected CdA and Crr data to your ride file your average watts go way up to 159W, which looks right for your bike speed of 17.6 mph.

I will send you a separate, corrected ride profile by private email. Load this profile into your iBike and all will be well.

[Velocomp]

Looks like Tom beat me to it with a corrected profile

[Roubaixalltheway]

Thanks guys you are the best. Now if I could get HR as a % of Max my iBike Pro would be Perfect.