Weight head assembly for dumbbells that eliminates a weak point on the handle bar, so as to increase the durability of a handle bar on dumbbells. Under present invention, the ‘stub’ portion, where the handlebar is inserted into the weight heads on the two ends of the bar, need not be machined down in size at the junction point between handle bar and weight head, and can thus withstand more wear and tear for regular usage in fitness training. The cost of manufacturing the handle bar, and as a result of the increase durability, will help the fitness industry greatly when making new dumbbells.