Sometimes, when riding low-wattage intervals, riders may experience what we call the "wattage floor" - essentially the trainer's lower mechanical limit. When this happens, riders may not hit their target watts for recovery intervals since the target power is beneath the "wattage floor" of the trainer.
Simply put, a wattage floor is when the number of watts it takes just to turn the pedals is higher than the target power. Depending on your gearing, might take 100 watts just to make the flywheel spin!
When you come into contact with the wattage floor, it will often appear as though your power is "floating" above the target power. Each trainer is slightly different, but most commonly riders will encounter the wattage floor when riding recover intervals below 100 watts.
Fixing a Wattage Floor
The good news is that the wattage floor is usually pretty easy to avoid. If you find that you're running into the wattage floor, check your trainer's manual to see what gearing they recommend.
Switching into an easier gearing combination should resolve a wattage floor, though we'd recommend going with the trainer manufacturer's recommendation before trying this. The trainer's wattage floor is lower when using easy gearing combinations, so down-shifting should allow you to reach those low power targets.