While I concede that I have become slower on qwertz keyboards over years of not using them, your bicycle example is wrong.

I'm an avid fan (and rider) of unicycles and recumbent bikes like the Flevo Racer. The Flevo Racer's pivotal steering makes you have to learn biking again from the ground up. It takes a few afternoons (or faster, if you aren't that clumsy). Riding a unicycle took me two weeks to learn.

Nevertheless, I can still ride a standard upright bike without any problems. And after all this crazy wheeled stuff, even bipedal locomotion still works fine.

Skills don't have to crowd each other out.