I’m in the midst of a very long term test of the new Gen III iBike Aero, but given my penchant for wordiness, I thought it’d be best to break it up into a few segments lest the review reach Tolstoyean proportions. So here’s a quick intro with some preliminary findings.

The iBike is a nifty little power meter that quantifies the rider’s output by measuring all the forces that oppose forward movement with an array of sensors. A pressure port and and barometer measure wind speed, an accelerometer measures acceleration and road grade, and speed and cadence are picked up by ANT+ wireless sensors. Total weight is inputted by the rider, and CdA and Crr are determined by a series of coastdowns and a 4 mile out and back calibration ride. New to the Gen III system is a vastly improved application, improved tilt measurement, and most exciting of all, the ability to overlay the iBike file with numbers from another power meter, either on the fly with ANT+ compatibility, or after the ride in the application.

I found it difficult to do a calibration with the iBike this winter, at least one good enough to base a review on. You need a relatively still day to create a good profile, and winds have been high all winter. And with the huge variations in temperature, I found myself wearing vastly different clothes from day to day, thus altering my CdA and throwing off the numbers. So instead of using the iBike as a stand alone power meter I plowed ahead and used it in a couple of different ways.

On the Road Bike

I used the iBike as the computer head for a Quarq Cinqo, which, thanks to ANT+ can pair with a Garmin or an iBike (the iBike can serve as the computer head for ANT+ SRM’s and Powertaps too). Once paired up the Quarq sends power and cadence numbers to the iBike, overriding the iBike’s own power measurements on the display. The iBike’s own calculations, however, are still being made, and can be pulled up later in the app once the file is uploaded. Thanks to the iBike’s wind measurements, you can get some really neat race data. The second graph in the screen grab below is a comparison between ground speed and wind speed. When the blue area is below the white line you either have a tailwind or you’re in a draft. When it’s above the white line you have a headwind.

This was a short lived escape where I followed a rider off the front (the 800 watt spike in the beginning). Once away you can see where we trade pulls from looking at the notches in the wind graph. Note how the power spikes correspond to my pulls.

Here’s a state line sprint on a training ride which illustrates the level of detail you can get from an iBike file. I’m in the draft from 1 to 2, but am forced to the front from 2 to 3. I soft pedal and fake a jump from 3 to 4, resulting in a drop in speed, which coincides with the road turning up, as you can see in the slope graph at the bottom. The other guy jumps at 4, and I get on his wheel from 4 to 5, finally coming around from 5 to 6.

Time Trialing

I have a wired SRM on the TT bike, so I have to use both computers on the bike and upload the files separately. Once uploaded the iBike app uses speed data to match up the two files perfectly and merges the SRM’s power numbers over the iBike file. Once imported the composite file is just like any other file, with the SRM data embedded and saved.

Using the iBike on a TT bike used to be problematic, since arm placement in the aerobars interferes with the iBike’s pressure port. The iBike people started playing around with a hose to move the intake to a spot with a cleaner look at the wind. They thought about making a mount to hold the intake under the aerobars, but I suggested routing the hose to a handgrip. So for full disclosure purposes, I have an emotional stake in this setup, but not a financial one. The ‘Remote Wind Sensor’ consists of a plug that fits into the iBike’s pressure port, a hose, and an intake cup. It should be available in 2-3 weeks, and will work with all versions of the iBike.

I’ve been testing a prototype of the remote sensor of the last couple of weeks. The file here is from the Readington Time Trial on 4/11, a cold and rainy 8.8k. Now, remember how each ride file contains two sets of power data: the iBike calculations and the SRM data? The cool thing about the iBike app is that you can tweak your CdA and Crr numbers after the fact, which then alters the iBike’s power numbers. I inputted .0048 for Crr (a guess taken from this table) and played around with the CdA until the iBike’s average watts matched the SRM’s average watts. The CdA I got was .24, exactly the same number measured at the CCNS wind tunnel.

Give it to me in broad strokes, kid

Ok, so brevity escaped me again. Here’s the quick version. If you’re running an ANT+ power meter like the Quarq, you’ll need a computer head. Why not get one that gives you valuable race data? As for time trialing, it looks like there’s a good chance that the iBike can be a mobile wind tunnel. But there’ll be many many more experiments to do before I can say that definitively.