The size restriction for cabin luggage vary between different airlines. Click HERE or HERE to see. With the Trinity SuitCase you can always fly with hand luggage of the largest size allowed by a specific airline. When in 35 cm width format (the mimimum size), the contents of the ViolinCase may create small bulges in limited side-sections or at the top; you can choose where, to ensure you will pass the cage test). You can put the SuitCase into a 35cm wide cage at the airport and the small bulge will move so your suitcase will fit in, no matter which direction turned. At the most common 40 cm width nothing protrudes outside. The airlines with the minimum width of 35-36 cm (several American airlines, for instance) allow on the other hand thicker bags (23-25cm) so you can fill the top pockets of your SuitCase or expand the whole lid.
Recently there was some rumors about forbidding wheeled suitcases in Venice because of noise they create/produce. With Trinity SuiteCase it wouldnt be a problem its already Venice ready!
If you still feel uneasy about rolling the Trinity SuitCase with your violin inside on an uneven surface you can always carry the Violincase on your back and put it inside the SuitCase when you arrive at the airport. The floors there are always very smooth, so there is no risk of shaky ride.