On again - Off again

For the last three months I've been working therapy on my neck and trying to ride. I did 50 miles in Colorado on a rented bike, and all seemed well. Back here in Austin, I did 18 (admittedly MUCH harder hilly miles) on my bike, and my arm is tingling again, as well as new neck pain. What gives?

Now I am thinking the bike is not the proper form, which would make sense. Folks have pointed out to me that the top tube is longer than it should be, so I lean further forward than I should, while trying to lift my head up to look. This poor posture == an RSI recipe for neck pain.

The next step is to beg or borrow a bike similar to the one I rented and make several runs with it.

Blood sugar numbers look good when cycling, so gotta do it.