So...I've cycled indoors on the spin bike three times (40 minutes each time) in the last few days. First two times, no tingling. Today, tiny bit of tingling in the left fingertips, the extreme tips, but...I'm not convinced the pinky's tip is tingling. It's hard to be sure. In any case, the tingling stopped two minutes after I lifted my left hand from the bar. I continued cycling with only the right hand on the bar.

All three times I made an effort to keep my palm unweighted mostly, especially the section of the palm towards the wrist. Today I changed hand positions more often. The wrist was bent at weird angles from time to time.

As the tingling started to go away, I did get a feeling of blood returning. The feeling is hard to describe, and it was quite subtle. Maybe I made it up too!

So...Just a guess here, but my thought is it's not caused by a disc in the neck, since when i lifted my hand from the bar, the tingling went away in two minutes. My body position stayed pretty much the same. If I can later confirm that the pink isn't tingling, just thumb through ring finger, that points to carpal tunnel.

Another bit if evidence, don't know if it's related. Sometimes I get tiny little creases in my fingernails, not length wise, but across the nail. It's usually just one finger, but last May, I noticed the lines (very light creases) across all the nails on the left hand. They were not deep creases,quite shallow, but they were there. I showed my doctor, but he thought nothing of it. They say the lines could be due to the the nailbed not getting nutrients or blood that it needs to lay down nail at a point in time, Using the estimated growth of a fingernail, and the distance of the dents in the nail to the nail bed, I traced the time back to March. the only thing I did in March was a 60 mile gravel ride. I don't know whether the fingers were buzzing, but I know when they do buzz, the buzz is a lot more than just the faint fingertip buzz I'm getting on the indoor bike.