I don't know his reasons, but in some cases of just feeling uncomfortable balancing the bike at a low speed or holding it up at a light, a CanAm Spider or even a traditional trike can help out an allow some to continue to ride. These obviously can't solve all issues, but it might be worth a chat. My uncle finally decided he had to have a trike. Unfortunately I've been without my dad since '92, so I never had to see that side. I imagine it would be easier this way than if you saw it was unsafe and felt you had to convince him to quit, or worse, take it away. If it's not in the cards for him to ride again, I know you will find many other ways to enjoy time together. Wishing the best for you both.
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