In slope mode (gradient) - what is the 'dialog' like between an app and the trainer?

Out of curiosity, does anyone know what is ‘dialog’ used between a training app and the trainer when in Slope/Gradient mode?

Is it in the sort of -

“Based on this current % gradient and the rider overall weight (etc.), I’ve made the calculation and you should set and simulate your resistance at X watts”?


“This is the current % gradient- simulate the resistance as you think you should and were programmed to”?


Pretty sure mine is just “do x% of maximum resistance”. The trainer is not allowed to answer back, so there is no dialog.

The protocol is ANT+ FE-C or Bluetooth FTMS.

This. Your other example, the training software tells the trainer a particular wattage. That goes against the key difference between Resistance and Erg mode. Forget about how a resistance or power level is picked. The fundamental difference between the two modes is that in Resistance mode, the resistance is “fixed”, so the power produced varies based on your cadence; in Erg mode, the power produced is “fixed”, so the resistance varies depending on your cadence. (This is from the perspective of the software. For the trainer, Erg mode tells it to use a control loop to alter the resistance in order to achieve a particular produced power.)

According to the protocol, FE-C has a “track resistance” mode, where the software provides rider weight, bike weight, wheel diameter, slope, and rolling resistance and the trainer sets the resistance accordingly.

1 Like