False Flats

[biker2000on]

In most of my riding the power numbers look very reasonable, ie when climbing, descending, or on the flats, but the iAero seems to be having trouble on false flat roads for me. I don't know what kind of error this would be from. I just got it a couple of months ago and have tried to carefully calibrate it. I'm thinking the CdA may be too low, but I don't really know how to tweak it without effecting other data.

Here is my data.
total weight 185
CdA .325
Crr .0055
Wind Scaling .604
Riding Tilt -.8

[racerfern]

Actually, other than your riding tilt being slightly higher than most, your numbers seem to be dead on.

There is no such thing as a false flat to the iBike, you're either climbing, flat or descending. The mind plays games and after you've adjusted to climbing for quite a while it's amazing at how a lesser hill can look flat. You may not be pushing as hard as you "think" you are.

[biker2000on]

I was riding on the road that was in question again yesterday and realized that I didn't mention that it is extremely bad pavement. Heavy chip and seal. Will this make the ibike under report? I seem to remember that I read the Gen III units are much improved in this area, and according to Boyd it is generally fixed.

[Foothills Rider]

I live in a part of Texas where chip seal is way too common. In those days with vibration problems (and correct! those days are now gone), your watts would tend to have incredibly high peaks....1500, 2000 watts would just sort of pop up. It was never a steady under-reporting, it was just all over the map incorrect, and it would be very obvious as you looked at the results...

Bill

[lorduintah]

With the vibration issues pretty much minimized, the friction/Crr will be modified from your calibration - if this road has a significantly different surface. The result would be less power than a true estimate, because the actual conditions are more severe. So it is likely that your watts would be on the low side. Any deviations are more likely to be from the differences in road conditions than the grade of the road. Think about what it would be like riding on a very flat gravel road vs. a fresh paved asphalt one.

Tom

[racerfern]

I was riding on the road that was in question again yesterday and realized that I didn't mention that it is extremely bad pavement. Heavy chip and seal. Will this make the ibike under report? I seem to remember that I read the Gen III units are much improved in this area, and according to Boyd it is generally fixed.

At what mileage in the ride file you posted is the chip seal, false flat area?

[biker2000on]

The chip and seal section is where my heart rate is sitting steady at 170 or so. Miles 53-56 approximately. I was going threshold approaching the state line into back into TN and that is why I don't believe the power numbers. It felt more like 300 or so, but maybe I am wrong. I am new to the whole power meter deal. Thanks for answering my questions.

[biker2000on]

Thanks for your help. I think the calibration is pretty good and it is much more likely that I am just getting used to the power meter. It feels like I am pushing a lot harder when I am on a big gear on a flat or downhill road than when I am in a small gear cranking out the hills. I was doing experiments with that, and it seems to be my problem, not the ibike.

[Russ]

biker2000,

I have found the iBike to be quite an education in a number of areas Just remember that power is a function of both the applied peddle force and of the cadence. So a high force at low cadence may be the same or even less power than a lower force at high cadence. Oh yea and a higher cadence may save more for that next hill too! Of course the big gear is often thought of as a good part of training too. But IANAC (I am not a coach .

Russ

[lorduintah]

Agree Russ,

This year I have gone to higher cadence riding (from 65 to 85). I find it easier and when I need more oomph - a higher cadence leads to higher power output without a big burn right afterwards. I still get the elevated HR, but also a faster ramp to high power.

Tom

[rruff]

I was riding on the road that was in question again yesterday and realized that I didn't mention that it is extremely bad pavement. Heavy chip and seal. Will this make the ibike under report? I seem to remember that I read the Gen III units are much improved in this area, and according to Boyd it is generally fixed.

Mine under reports power on rough roads... sometimes extremely so. It isn't the power spikes I'm speaking of, rather the slope reading is low. The Gen2 and Gen3 (my wife and I) were both unusable at Moriarity this year for this reason. A series of larger jolts seems to effect it more than a consistent rough pavement like chipseal. The road at Moriarty had lots of cracks.

[travispape]

Mine under reports power on rough roads... sometimes extremely so. It isn't the power spikes I'm speaking of, rather the slope reading is low. The Gen2 and Gen3 (my wife and I) were both unusable at Moriarity this year for this reason. A series of larger jolts seems to effect it more than a consistent rough pavement like chipseal. The road at Moriarty had lots of cracks.

Hey Ron. How is your iBike mounted? Can you send me a ride file that demonstrates this rough road phenomenon so I can take a look?