Welcome to FT, Tweener!

You should also watch out for total weight. The European airlines often only allow 7-8kg of carry-on weight. Getting backpack straps PLUS wheels will give you a bag that weighs at least 3kg. I suppose your laptop weighs at least 2.5kg with the power supply or you wouldn't want a rolling back. You are getting very close to the limit here.

Pack all your stuff together and weigh it. Then check the airline weight limits in addition to the size limits. Only then can you make the decision if a wheeled backpack even makes sense.

Till