Bicycle helmets are made to protect against one single impact, not many. Bicycle helmets are not football, hockey, or baseball helmets. Bicycle helmets are designed to protect the head from one hard hit against the road surface. Unlike football and hockey helmets, they cannot withstand lots of hard hits. Bicycle helmets also do not protect the ears like sport helmets do.
Bicycle helmets are for in-line or quad skating.
Skating helmets have only recently been introduced. They have been designed like the bicycle helmet to protect during a single hard hit. Both bicycle and skating helmets are required to meet the same standards. For this reason, they can be interchanged. There are helmets designed specifically for this.