Cycling has been shown to be an effective exercise to help manage PD. A researcher at the Cleveland clinic, Dr. Jay Alberts, discovered this when he was tandem bike riding with someone with Parkinson's. When they got off the bike, this person had a significant reduction in tremor and improved handwriting.
From there he went back to his research and has been focused on how bike riding, especially at a higher intensity, can be beneficial for those with PD. In his research he uses stationary bikes to have participants cycle at a higher speed then they would self select. By working at a higher speed there have been positive findings in:
Improved rigidity
Improved tremor
Improved quality of life
Improved sleep
Improve balance and walking'
Improved attention and memory
Decreased falls
How can you get into cycling?
Pedaling for Parkinson's is a group that offers in person classes through the YMCA and also offers virtual classes. A class is an hour long with a warm up at 60 RPM, followed by 40 minutes at 80-90 RPM and then a 10 minute cool down.
If you have a stationary bike at home, you can follow the same structure as the pedaling for Parkinson's group. (*** It would be best to work with a physical therapist or trainer when you are starting out at a higher intensity)