Ethical question

I am, yes.

It's only a bike, this in not Darfur, let him dress his bike up as he likes, I agree it would be dodgy (I save the term 'immoral/unethical' for more lofty concerns) if he were to attempt to pass it off as something it was not when selling - but he has not said he is doing this.

Of course you can ! Just don't get caught ! :P Your avatar nicked from the BBC weather website is not going to be of interest to the BBC lawyers any more than some bike fan sticking some logos on his bike or someone nicking McDonald's logo for a piss take T-Shirt.

I don't see any of this as a big thing, certainly not an ethical question.

Actually, passing off a bike with someone else's logos could devalue the brand, particularly if it happened commonly.

For example, if you saw a slack-geo'd poorly built rust-bucket with Bob Jackson written down the side, you might raise an eyebrow and wonder to yourself if perhaps they're not all that good a framebuilder after all. So BJ is loth to sell decals to anyone to ensure that precisely that does not happen.

To take an example from a different industry where counterfeiting is endemic, Rolex is always very keen to explain to people exactly how the movement should look on an Oyster (the second hand moves smoothly, rather than ticking), because the counterfeits are unreliable and could reflect poorly on the brand if people did not know they were counterfeits. (I used to live in Singapore, which at the time was a bit of a counterfeiting goods hub).

I agree that 'immoral/unethical' is perhaps too hyperbolic language to describe this, but essentially what Yossarian is suggesting will help debase the currency of whichever brand he chooses, and the chances are the bike company in question won't be keen to help him achieve that.