In light of what the government likes to call “the UK’s new relationship with Europe”, are there any issues with taking an expensive bike into the EU (and more importantly bringing it back)?

The government website is predictably vague when talking about duty free limits and carnets and such like. There is a page stating what is covered by something called an ATA Carnet which includes sporting equipment, although that is written from the perspective of importing to the UK.

I know that motorsports events have been affected as any non-road registered vehicle in theory needs a carnet, but does this also apply to bikes?

I’m sure I’m probably overthinking this, but curious what the letter of the law says in case some jobsworth at Dover decides they want proof that you haven’t just bought that shiny (?) bike in the EU and are trying to smuggle it in.

I went to France last month and had two bikes with me, wasn't a problem at all. The gendarmes asked to see in the back of the van for anybody hiding in there but couldn't give two hoots about the bikes.
Portsmouth were also not interested, didn't even look at our covid pass's, just passports.
Wouldn't worry about it.

Way back in the day, 1979 to be precise, I "imported" a camera from the USA. I declared it at customs. Even back then in pre-internet days they had access to the serial numbers of officially imported items and could determine if it was one of those.

I'd imagine the frame number of your bike will have been sent to HMRC when it was originally imported so if you were stopped they'd soon know one way or the other. Jameso might be able to comment more accurately. Also being a "single trip" you are unlikely to attract attention, it's people going back and forth every day that they keep an eye on unless they've intelligence to suggest otherwise.

Hmmm.....

I'm driving over to the UK from France in a couple of weeks and bringing at least one, maybe two bikes with me for the trip.

Not planning to do anything other than arrive with my bikes in the car.

Not heard of anyone having issues so fingers crossed it'll be reet!