Tom
I have six motorcycles, I am not going to buy 6 vignettes for them.
I used to put it inside the transparent top of my tank bag. Couldn't tell if it was properly stuck down or if there was a layer of clingfilm between the sticker and the plastic.
During my first 7 years in Switzerland I drove without a vignette...out of pure ignorance.
Mine is attached to a frame tube, but is easily removable, so I secure it with a cable tie.
Tom
Better do it like Tom. Because you have to attach the sticker to an easy accessible but not easily replaceable part of the bike otherwise it will be void. Art. 3 NSAV .
They should allow it to stick it on the back of the license plate. That way you could legally share it with two bikes, which can anyway never be on the road at the same time.
Question: Has anybody on a bike ever been checked?
In practice (and I only got checked at the border a few times) they accept that it's actually very difficult on many bikes to find a suitable place to stick it securely, so they're perhaps a little more lenient about this than they are for cars.
Anyway, I don't ride any more, so it's a moot point for me.
Yes. At motorway border posts.
The most secure place, if someone is concerned, is just under the seat. I for myself have it on one bike on the rear facing part of the front fender; a place where anyone can see it, where it gets really, really wet and dirty, and from where it has never diapered.