I have your thumb problem. Brought on by working on bikes, model raileays, caravan, cars, motorbikes . . .I was not gentle with those little appendages.

The race bike style gear changers for drop handlebars are fine, and you can use them on curved bar ends too with great control over your brakes etc. Releasing the gears can be tricky when you press that little black thing, but bearable.

The old SIS levers they had 30 years ago on those off roaders that swept the market are in short supply now. You might get a 7 speeder, as I have in prep fpr the future . . . These were fuss free and were the equivalent of the old downtube shifters of the racing /road bikes 60`s era and before.

Now why they don`t make a straight handlebar equiv of the modern brake lever /gear change I`ll never know.

Business opportunity! Anybody listening?