What do the numbers 1, 3, 7, and 21 at the end of a model name indicate?Updated 15 hours ago

Sun Bike and Trike models have different configurations based on drivetrain speed options:

• 1: This model features a single speed.
• 3: This version is equipped with a 3-speed internally geared hub.
• 7: This model includes a 7-speed derailleur system with a single front chainring.
• 21: This variant offers a 7-speed derailleur system with a triple chainring, totaling 21 gears.