Ambrose that’s not correct that depends on the airline. We flew to India with MTB’s in Jan and had a 30kg luggage allowane and 7kg handluggage, we flew clothing handluggaeg for 2 weeks and stuffed bike bags with helmet, shoes, tools, camelbaks, wash bags etc. However having previously flown Easy Jet they WILL NOT allow anything packed into the bag and they have been known to check. All airlines differ as to whether they way them or not and be warned we have had BA to Geneva not weighed on way out but have been weighed on the way back in.
Mr MC Orange Alpine in bike bag with LOTS of packing, shoes, camelbak, body armour, washbag, trail in it etc weighed in at 28kg.
EDIT: Easyjet allowance will be 32kg if flying with bike. Once had friend who flew Easyjet to Geneva and he had EVERYTHING in his bag, no other checked in or carry on luggage, it weighed 50kg or whatever the MAXIMUM weight full stop is….check in girl laughed said “it’s the heaviest bag I’ve ever seen” and checked in it .. no extra cost! He was young and good looking 😉