Fun fact, the word 'cassette' refers to the plastic box, not the tape inside. It's a 'cassette tape' because the tape is protected inside a cassette. You used to be able to get CD cassette drives where you had to put the CD into a removable cassette which you then inserted into the drive.

bicycles have a cassette of gears

Genetic cassettes:

https://en.wikipedia.org/wiki/Gene_cassette

I didn't know that was called a cassette. I always assumed cassettes were a type of cartridge with reeled tape.

The etymology of English "cassette" appears to come from the French word for "little box", which makes sense for tape cassettes but not for bicycle gearing. Considering that bicycle cassettes were invented in the 70s whereas tape cassettes are from the 60s, I'd be curious to know the reason for the name.

https://www.etymonline.com/word/cassette

Little box to hold a removable piece or mechanism, so seems a bit of a stretch unless cassette gears pop out for replacement? There were far earlier uses. The box that held the glass plates in early plate cameras was called a cassette.

I figured it was from case + -ette, like a small case.

Colloquially, tape as a synonym for record (verb), or to 'get something on tape'. I'm still guilty of using it sometimes.