Unlike other smart trainers that have electronic resistance and measure power based on the resistance applied, the Stages SB20 has individual power sensors on both crank arms in addition to the electronic resistance unit. 

StagesBike with arrows pointing to the two power meters on the crankarms

SB20 view from above with the upper PCB labeled

  • Right: Right-crank power meter
  • Left: Left-crank power meter
  • SB20: The bike's internal computer is inside the phone holder. It connects to all your apps, allows you to control the flywheel, and connects to the power meters.

How it works together

The right power meter measures the power from your right leg and sends that information to the left power meter. The left power meter measures the power from your left leg, combines it with the right side's power, and sends that as the total power over ANT+ and Bluetooth. So anytime you just want to pair the bike as a power meter, you can connect to the left power meter and receive the same metrics as you would when paired to a Stages Power LR system. 

The smart bike pairs with the power meters and rebroadcasts the same information as the left power meter. So when you pair an app or cycling computer to the bike, it gets the same power and cadence as if you paired it directly to the power meter. 

The resistance unit does function similarly to a power meter and exists in the flywheel, but this is used for control only. The power meters are the primary source of information, as they measure power directly, and the StagesBike adjusts its algorithm according to the error between the flywheel and the power meter's real values. Since we use the power meter data to adjust the resistance level, there is no need to zero reset the StagesBike or do a "spin down" as you do with other smart trainers. When you zero reset in the Stages Cycling app, the app resets only the power meters, not the bike. 

With power meter firmware v. 1.6.8, we introduced an automatic zero reset so that it is not necessary to zero reset your power meters every ride, however, some may find they prefer to do a quick zero reset before every ride.