As per title really. Using a set between my 29er and my CX race bike, not that hard to swap tyres around but is it likely to have a detrimental effect on how well seated and sealed they are, over time?

wouldn’t think so – you’re more likely to wear they tyre out before the rim beading.

Unless you’re using razorblades for tyre levers of course.

In my experience, no. They are either fitted properly or not, and refitting them repeatedly does not seem to inhibit their ability to be fitted correctly.

Cheers!

(although really I was after some justification for my laziness so I can buy a new set of wheels)

No, it’s terrible. Buy some more wheels.

It’s an awful waste of time! And as rims wear out from fatigue and hubs from usage then it would be more cost effective in the long run to buy another set of wheels – although harder on cash flow right now.

Buy away! 😉

It’s fine as long as you aren’t subjecting the wheels to different disciplines. All MTB, fine. Don’t swap one set of wheels between, say, road racing and BMX, or MTB and cyclocross – that’s very dangerous and it would be better to buy a second set of wheels.