Keep it simple. You're retired from healthcare. Any follow-up questions, just keep it simple. As a recovering over-sharer (except on PC..heh heh), I am tight lipped with everyone until I get a sign from them, that i can open up more about myself. But, there's always that risk that they still reject my friendship anyway.

Also, most people love to talk about themselves. Dale Carnegie said, "Talk to someone about themselves and they'll listen for hours." So, you can always deflect away any uncomfortable personal questions with a random comment or question about something that person told you, or about pop culture, music, sports, or whatever. Talk about cycling.

You have a lot to offer people. I can't use a platitude right now or I will barf on my computer screen. So, I'll just say to trust yourself. If you trust yourself, you will be ok. People take their social cues from others. So, if you come across as your true self -- relaxed, funny, engaging then these guys in these cycle clubs will see that you are someone they can feel comfortable around.

edit to add: Humor is a huge ice breaker. If you show that you have a sense of humor about your bipolar disorder (when the subject eventually comes up in conversation), that will immediately diffuse any awkwardness for the guys listening to you share your story. Humor works magic like that. Always make a joke first. That puts people at ease.