1. decay, decline(noun)
a gradual decrease; as of stored charge or current
In a nutshell: Because InfoCrank’s system will accurately measure down to 5 rpms versus a much higher minimum cadence used by other powermeters (20-30 is a common minimum rpm measurement).
A power meter’s computer module records cadence every time a switch is triggered but what if there is no trigger? After a few seconds ANY program has to make a decision….is the cadence just slowing or has it stopped?
Other systems will set a very high minimum cadence such as 20-30 rpms and then hold the last cadence when the cranks stop rotating so after 3-5 seconds it will show a zero. But any cadence under 20-30 rpms is then erroneously recorded as zero.
Because we can measure down to 5 rpms, this would require our computer to hold the last cadence for 12 seconds waiting for the next trigger. So, we have chosen to display the cadence as decaying in case the rpms truly have dropped to a very slow rate rather than completely stopping.
This is how it works:
If a cadence trigger is late by more than 0.5 seconds and then every second thereafter we calculate the maximum possible cadence and transmit this to the display. The true cadence could be less than this value, but never greater.
Once the cadence is more than 15 seconds late (4rpm) then 0 cadence is transmitted to the display.
If the rider suddenly changes their cadence to a lower value, say from 90 to 20, then over the 3 second period, the display will show ...90, 90, 60, 30, 20, 20... That is it decays RAPIDLY to the new value.