In my early days of cycling- 20 years ago- I was a person who had a cycle. Luckily I rode with cyclists. They taught me a lot- One of which was how to change gear under pressure when going up hills. They got fed up with hearing me graunch the gears as I changed. Took about 2 or 3 rides with plenty of steep hills and I knew how to change gears without messing up the cassette or the chain.