Is the cross trainer or the elliptical trainer more effective?

What is the difference between a cross trainer and a elliptical trainer?

How much flywheel mass should an ergometer have?

What is the difference between an ergometer and a recumbent ergometer?

What is the difference between an exercise bike and ergometer?

Do I need to maintain the ergometer? Do the moving parts inside wear out?

11004 SOLE E25

11005 SOLE E35

11006 Fly RX