sogood said:
Match the competition or exit the market, isn't that's the law of business. The question really is just how good and accurate iBike is?
From what I understand, the iBike is just as accurate as those other units, and more importantly, just as precise, especially after the latest firmware upgrade. Accuracy is much less important than precision, because being precise means being able to repeatedly report a value that within the desired range. Something can be accurate but have poor precision, and something can be inaccurate but have great precision. The difference is that with good precision and poor accuracy, good accuracy can be derived by just finding how much the reported data is offset from absolute accurate data. However, as I stated, the prevailing opinion of users so far is that the iBike is both precise and accurate.
The firmware upgrade that happened was done to condition the signal out of the accelerometer. The initial firmware settings were such that the signal out of the accelerometer would read the noise from roads causing vibrations of a certain frequency, losing the desired signal in this noise. Apparently one thing that the latest firmware upgrade did was to damp the response of the accelerometer so that it wasn't sensitive to the higher frequency vibes of the road (which are many orders of magnitude different than the frequency spectra expected from human supplied power). One user 'round these parts said that the firmware upgrade did the trick.
The difficult thing for the other power meter makers will be keeping the precision and accuracy of their units WHILE lowering costs. If the iBike is indeed as accurate and precise as the Ergomo, the SRM, and/or the PowerTap, then those companies will either have to find a technological trick to allow them to drop prices and maintain their level of performance or they will have to accept a lower level of performance.
The iBike approach is very interesting since the only hardware it relies on for power calculation is the accelerometer and a pressure sensor. Both of those devices are well known and can easily be "calibrated" with software. They can also be easily "filtered" with software filters so that the desired data isn't lost in noise. Also, they can be made accurate by just testing the units to find how much their results are offset from known accurate results and then by just adding a software "offset" to bring the results to the required level of accuracy. This is a tried and true technique with all sorts of electronic measurements.
I had an experimental apparatus running that did optical testing of a mirror surface using liquid mirrors (aka, liquid mercury) as reference surfaces. The liquid mirrors were uber sensitive to the lowest amplitude vibrations, like air turbulence caused by temperature differentials in a 3 story room. By applying software "filters" we were able to remove the noise from turbulence to uncover the desired signal....which was of a much lower amplitutde. Again, this sort of thing is done all the time.
What makes the other powermeters so expensive is the need to have a highly accurately machined piece--a BB axle, hub axle, and etc--to which a strain guage is attached which measures deflections of that machined piece. It's that precise machining that makes the things so expensive. Also those powermeters require more hardware, specialty hardware, which only adds to the expense. For example, with SRM you can't just buy their bottom bracket with strain guage attached. You have to buy the computer and wiring harness AND the crankset. Power tap requires that you buy the computer, wiring harness, AND a specific hub. Ergomo requires the purchase of their BB and possibly a specific crankset (you definitely cannot choose any crankset.). The Polar unit isn't so expensive and doesn't require a lot of expensive equipment, BUT it is very sensitive to setup, sensor alignment, and a few other things. The Polar unit, because of its sensitivity to more factors, has more degrees of freedom and as result is less precise and less accurate.
I hope that iBike is the inspiration for a new trend of precise, accurate, and relatively cheap power meters. Power meters may be the greatest training tool for cyclists to date. As such, it's not good that their use is restricted to the wealthy, the well sponsored, or the racer crowd. Powermeters--especially the iBike--hold the possibility of improving cycling and opening possibilities for people with certain diseases. Diabetics, for example, might be able to use iBike to calibrate their own carbohydrate metabilization curve or blood sugar curve based on iBike readings. Even better, it might be possible for some slick software guy to write such a diabetic calibration software module that can be added to iBike software that would give periodic messages to the rider, like "Eat this much, now." This could revolutionize cycling for diabetics and non-diabetics. It could make bonks things of the past. Imagine, even for non-diabetics, how nice it would be to have software calibrate to your metabolism that alerted when and how much to eat or drink. That would truly optimize performance.
