Dupuytrens contracture.....my father didn't leave me money, but he did let me inherit this.
I'm really lucky so far. It's just in my left pinky, which is curled into a permanent hook.
(I had a couple crush injuries to that finger as a kid.) But it still works on a keyboard.
For everything else (eg, weightlifting, shoveling), it stays out of the way, unused.
Grabbing anything I avoid using it because I might not be able to let go.
Surgery could fix it. But with the risks, pain, expense, & inconvenience, I prefer to cope.
Fortunately, bike handlebars are no problem at all.
Consider recumbent bikes. If you're willing to be nerdy & fast, there's no hand pressure.