I'm 73 y/o. No Parkinson's but I have lumbar spinal stenosis and riding a road bike is what my spine doc recommends to ease the discomfort in my back. And he is 100% correct.
A few of my neighbors who aren't cyclists and have SS look and act much older than me. For some, walking is a chore.
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The Lord is merciful and gracious, slow to anger and abounding in steadfast love. - Psalm 103:8
I am a cyclist. I am not the fastest or the fittest. But I will get to where I'm going with a smile on my face.