Here is a motorized mini bike you can use in your office to get a light workout. The SF-B0717 Electric Surface Cycle 90 can get your feet and arms moving. It has a motor with 12 adjustable speeds. The entire bike weighs only 17 lbs, so you can move it around easily. It can handle users up to 220lbs.
You can achieve up to 90 rotations per minute on this bike. It has a digital monitor to show time, direction, speed, and RPM. It has a footprint of 20L x 18.5W x 14H.