Spend $499 and get the lot. Left right leg power, sway of the bike during any wasted power section, interchangeable between 4 bikes that takes about 3 seconds in change over. Has the accuracy of the far more pricy units, weighs 180 gramms, it’s own software that my data engineering gurus salivate over, has speed, cadence, heart rate, hill climb in metres and degrees, powered by internal battery. All ready in one unit at $499 with warranty for two years.
The ibike power metre, try one free if you like. Email me at luke@velocoaching.com.au