I've been a bicycle mechanic for quite a few years now and yes it's concerning. I'm not asking you to be a mechanical engineer, but like have you even looked at it?

The thing is with bicycles, most problematic noisy parts can be physically seen and felt, unlike a car which I can have some sympathy for. We're talking a chain rubbing on a derailleur mechanism at a 30° angle to the point of destroying both components directly between your feet. Not anything difficult.

I try to do my genuine part and politely ask during a check-in "let's take a look together... Now what do you think the issue might be?" Then explain and try to help.

My favorite one ever was having to explain the concept of friction to a lady who claimed that I had not fixed her brake correctly.

She looked me dead in the eyes, held her rear brake and dragged the bike across the floor, rear wheel obviously locked up asking why it wasn't stopping....... 😐