The PFS provides a theoretically-sound pedal force over a full range of pedaling conditions including sprints and out-of-the saddle efforts and climbs, workouts that you can't do on trainers.
The PFS models power within a pedal stroke correctly. As a consequence:
- Hills feel like riding hills. When riding hills outdoors one's cadence naturally falls. And so it does on the PFS. This is a definitive indicator that the simulated pedaling is correct. Trainers don't respond this way.
- One can sprint out of the saddle. This allows you to train for sprints indoors without having to ride to a suitable training spot. One can train for sprints on a PFS; one can't on a trainer.
- One can train to climb long hills out of the saddle. On long climbs one needs to be able to vary one's position. Training to climb out of the saddle allows this. You can live in flat Florida and still train for long climbs using the PFS. One can't do this on a trainer.
- One can do standing starts. This is particularly useful for training for track events. One can't do standing starts on a trainer.
- Although less obvious, on the PFS simulated flat courses feel like they should. Trainers just never feel right even when spinning easy.
- By getting the force right at the pedal, the PFS allows one to duplicate indoors the subtle changes in position that come from increased power outdoors. Trainers don't get this right.