A quick post and something of a product endorsement.
For more years than I care to remember I have been strapping things to my bike with bungie straps, a length of elastic rope with a plastic-coated metal hook on each end.
They can and do snap, and with use the plastic coating gets worn and the now exposed metal bits can damage the bike’s paintwork.
On a recommendation from a friend, I bought some “Rok Straps”. These are regular nylon straps with an elasticated mid-section that you anchor to your bike by looping around a secure point.
My bikes mostly have racks and panniers so this is not a problem for me. If you have a modern sports bike you might have to get a little creative.
I used them for the first time last weekend and they worked as well as advertised. Easy to attach, easy to use, and no likelihood of damaging the paint.
If you are looking for something to tie your gear down you could do worse than try some yourself.