I want to buy a power meter for triathlon training & racing. Anyone have experience with iBike Sport or Pro? Are these products a waste of my money or are they good products? Should I save up more money and go with something else(Quarq, ergomo, etc)? If so, what?
The ibike is not a powermeter.
And don’t get an ergomo, they’re now unreliable and unsupported.
Powertap, quark and srm (if you have the money) are all fine.
The ibike is not a powermeter.
If you want to get technical, all of them are power estimators. According to this, the iBike looks pretty decent vs. PowerTap and Quarq:
http://www.ibikesports.com/documents/Johnson_ride_analysis.pdf
… According to this, the iBike looks pretty decent vs. PowerTap and Quarq:
http://www.ibikesports.com/...on_ride_analysis.pdf
Are you sure about that? It looks pretty bad to me. At one point for 1/4 KM, it was off by 150 watts. Other times it was off by at least 10%.
for the money you can’t beat the ibike… i’ll be getting and ibike aero soon, will see how it goes. a friend of mine has been running his ibike on his ergomo and powertap equipped road bike (yes he had three powermeters on there for a bit…) and actually found the ibike to be scarily close while riding solo. On our group rides however the pack seems to screw it up a good bit.
I’ve got an Ergomo pro i need to post in the classifieds… one year of use, just kinda stopped caring all that much about power for a bit and now the new bike sponsor is providing DA cranks so I can’t run it now that I’m looking for a meter again. If anyone wants it $600+shipping for a complete ergomo in grreat condition. Includes a ustom carbon mount for use on flat aero bars like the HED integrated.
… According to this, the iBike looks pretty decent vs. PowerTap and Quarq:
http://www.ibikesports.com/...on_ride_analysis.pdf
Are you sure about that? It looks pretty bad to me. At one point for 1/4 KM, it was off by 150 watts. Other times it was off by at least 10%.
True, but you can’t tell which one is “off” because none of them are ground truth, and the CinQo and PowerTap also didn’t correlate well at high wattage - the CinQo and PT were 200W apart during one spike (with the iBike in between). And I also see 1/4km segments where the PowerTap and CinQo are off from each other by about 10%/~100W. And not consistently, i.e. sometimes one’s the high one, and sometimes the other. Looking purely at that data you cannot claim to know which power meter is the most accurate.
But the telling number is an R2 of 0.925 compared to the CinQo over 4 hours and 15 minutes. That’s pretty good.
No, the iBike shouldn’t be used as an ergometer for scientific study, and it is suspect for very short spikes in power (as are the other two). But it looks to be a pretty useful tool, particularly given that you don’t need a special wheel or crank, and it costs less. I wouldn’t flippantly dismiss it as “not a power meter” which it clearly is.
I don’t know why anyone would be too concerned about the spikes either. Recording data every second over a 3+ hour ride makes any single spike pretty meaningless. Plus I think most programs offer some way to correct the data post ride.
The “accuracy” of the power meter is a bit of a red herring. It doesn’t really matter for training purposes if the power meter is accurate. It only really matter if the power meter is consistent. Who cares if one power meter says your FTP is 250 watts while another says it is 265 watts. The higher reading might make you feel better and you might think it is more “accurate”. But if you set your training zones to either FTP and use that same Power Meter while training then the only important factor is how consistent the power meter is in its own reading.
I haven’t looked into it too much but are their any independent testing of consistency amongst the various offerings? I use a Power Tap and I know you can set it to auto zero during a ride which is supposed to keep the data accurate throughout a ride. Which reminds me that I need to check that on mine now to make sure it is on. Do other power meters offer this self calibrating feature?
True, but you can’t tell which one is “off” because none of them are ground truth But the telling number is an R2 of 0.925 compared to the CinQo over 4 hours and 15 minutes. That’s pretty good.
You can do static calibration checks on both the PT and the Cinqo (and the SRM). You can’t do that on the iBike (or the Polar or Ergomo).
When comparing PMs, the important question isn’t “overall, how well do they compare?” The important question is “under which conditions don’t they compare well?”
The “accuracy” of the power meter is a bit of a red herring. It doesn’t really matter for training purposes if the power meter is accurate. It only really matter if the power meter is consistent. Who cares if one power meter says your FTP is 250 watts while another says it is 265 watts. The higher reading might make you feel better and you might think it is more “accurate”. But if you set your training zones to either FTP and use that same Power Meter while training then the only important factor is how consistent the power meter is in its own reading.
I haven’t looked into it too much but are their any independent testing of consistency amongst the various offerings? I use a Power Tap and I know you can set it to auto zero during a ride which is supposed to keep the data accurate throughout a ride. Which reminds me that I need to check that on mine now to make sure it is on. Do other power meters offer this self calibrating feature?
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Saying that the accuracy of a PM is a red herring is a red herring.
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The autozero on a PT isn’t the same thing as checking its calibration.
True, but you can’t tell which one is “off” because none of them are ground truth, and the CinQo and PowerTap also didn’t correlate well at high wattage - the CinQo and PT were 200W apart during one spike (with the iBike in between). And I also see 1/4km segments where the PowerTap and CinQo are off from each other by about 10%/~100W. And not consistently, i.e. sometimes one’s the high one, and sometimes the other. Looking purely at that data you cannot claim to know which power meter is the most accurate.
There have been plenty of studies of the accuracy and precision of the PT hub. Unless something was wrong with that particular hub, I’d trust the PT output to be closest to the “truth”…understanding, of course, that it’s fixed time base sampling technique will result in power “spikes” when looking at very short term outputs.
Another thing to remember is that the CinQo output is being recorded by the iAero…and my experience with an iAero of the same “vintage” recording a CinQo output revealed that there were periodic “dropouts” of the iAero recording of the CinQo that also “took down” the iAero internal power calculation. I know this because I also had a Garmin 705 recording the same CinQo data stream. The PT output and CinQo/Garmin output were nearly identical. This would probably be visible in Boyd’s data if it was plotted without any “smoothing” of the data (IIRC, his plots use the iBike software default of 10s smoothing). You’ll also notice some “hanging” power values on the CinQo/iAero plots…I believe that issue was fixed in a later iAero firmware release.
So…what I’m trying to say is, it’s a good bet that the PT is more “truthful”…although IIRC Boyd’s data also shows what looks to be some PT dropouts as well. My comparison was to a “wired” PT which has been rock solid for me.
But the telling number is an R2 of 0.925 compared to the CinQo over 4 hours and 15 minutes. That’s pretty good.
Well…considering what I discussed above, and also the fact that the iAero calculation was CALIBRATED using the CinQo output, I’d be fairly surprised if they WEREN’T fairly close…or else the iBike folks would need to work on their calibration technique/algorithm 
That said, as I discussed above, the more revealing statistic is how it compares to the PT…although, I sort of have a problem as well with the sort of statistic that the reported “R2” implies. IME, trying to “fit” to power meter data streams on a point by point basis is fraught with difficulties/problems due to timing issues. Besides that, if there are any significant sections of zero power, that (IMO) makes things seem closer than they actually are, since most PMs record zero power fairly well 
My preferred method to compare PM outputs is to plot the MMPs for each ride for the “stock” durations given by WKO+. One can either look at them as a linear fit, or as a Tukey mean-difference plot to get a feel for how well they “agree”.
In the end though, I DID find that under certain conditions the iAero could report power values strikingly close to the other PMs…however, as was pointed out above, this doesn’t hold when in a group. Solo rides are where it shines…as long as you have a good calibration.
Lastly, and I would think this would be important to triathletes, I found it to be somewhat difficult to mount the iAero in a spot on aerobars that gives good “exposure” to the wind pressure port…and also brings up the difficulties of the mounting ADDING drag for equipment/position where you’re trying (or at least should be trying) to minimize drag. In this case, other head unit options allow for a more “aero” mounting.
Just my 2 centavos…
Tom,
Were you able to use the iAero solely for recording/displaying power from the Quarq? I don’t care for measuring CdA in a race, i just want something that displays my output. To that end, would the iAero record power if it weren’t recording cadence,speed etc etc?
The one good thing i like about a PT is that there’s no extra crap being stuck to your downtube/crank arms/fork/spoke, while still being able to give you a cadence and speed.
Tom,
Was the iAero you worked with Gen II or Gen III? Or does that even make a difference?
Tom,
Were you able to use the iAero solely for recording/displaying power from the Quarq? I don’t care for measuring CdA in a race, i just want something that displays my output. To that end, would the iAero record power if it weren’t recording cadence,speed etc etc?
The one good thing i like about a PT is that there’s no extra crap being stuck to your downtube/crank arms/fork/spoke, while still being able to give you a cadence and speed.
I’m not sure if I understand the question…when paired with the CinQo, the displayed power is what is from the CinQo. You don’t see the iAero calculated power until after downloading. You still need to have a speed sensor, but the wireless speed sensor for the iAero is easily just mounted to the chainstay or seatstay.
Tom,
Was the iAero you worked with Gen II or Gen III? Or does that even make a difference?
The answer to both of your questions is…Yes
I was originally given a Gen II unit…but I had some problems with it (turns out it was actually an early prototype) and then had a short time with a Gen III. The Gen III incorporates some “real time” compensation for things like the tilt and also has a less temp sensitive wind sensor. Those things tend to help the Gen III display more accurate numbers “real time”. You can get good numbers out of the Gen II, but sometimes that might not happen until AFTER download and you have a chance to run the compensation routines…in other words, what you see on the display may end up being different than what you see after download/compensation. The Gen III has that “built in” and there’s less (if any) change. That’s obviously a good thing
My question was whether it is possible to use the iAero solely to display the power data transmitted from the Quarq and nothing else. If you remove all the other sensors for the purposes of racing, will the iAero still work simply as a power number display for the Quarq?
You mentioned that you need the wireless speed sensor on the chainstay. Can the iAero display power from the Quarq if you don’t want speed/cadence/HR?
My question was whether it is possible to use the iAero solely to display the power data transmitted from the Quarq and nothing else. If you remove all the other sensors for the purposes of racing, will the iAero still work simply as a power number display for the Quarq?
You mentioned that you need the wireless speed sensor on the chainstay. Can the iAero display power from the Quarq if you don’t want speed/cadence/HR?
Aaah…I see. With a CinQo you’ll automatically get cadence since it’s built into the crank spider and is part of the power calculation. I might be wrong on this…but I don’t think the iAero will function without a speed sensor. I don’t remember an option to turn on/off the auto start function for the trip timer…
If you don’t want an extra speed sensor, then a Garmin would probably be a better choice for you to read out a CinQo.
I might be wrong on this…but I don’t think the iAero will function without a speed sensor.
Even if you’re using it to read off an ANT+ PT?
I might be wrong on this…but I don’t think the iAero will function without a speed sensor.
Even if you’re using it to read off an ANT+ PT?
The PT IS a speed sensor…but, I really don’t know about that one…good question.
Really? You’re never going to switch powermeters, so that you’ll never have to compare historical data?
You’ll never try and do some aero testing in which case 15 watts=1.5 meters/second ?