Have used same skf ceramic bearings on my kart for 4 years and never had an axle come loose. Simply clean and relube them a couple times per year. Have had soft axles come loose that were tight with standard bearings. They work particularly well on soft/thin axles that are prone to come loose if not tightened significantly but are also dented very easily if over tightened. The skf bearings keep me from worrying about either denting an axle or having it come loose during a race. The price is not an issue for me when you take into account how much longer they last.