Am I missing something here? Surely when you break down a bike for the plane you have to take off the wheels and therefore have to remove the mudguards as well. The main problem is the fiddly hassle of fitting them back on at a foreign airport. I have always done it but I'm considering not doing it next time. Most of the crap thrown up by the rear wheel is taken by the underside of the rack where I keep my groundsheet anyway. My wife doesn't slipstream me on the tourer! Although the guards shouldn't get bent if they're removed and packed 'inside' the frame in the bag.