Simplify the following text for a Grade 11 native English-speaking person.
Original: The inline-four has become one of the most common engine configurations in street bikes The inline-four is common because of its relatively high performance-to-cost ratio .
Simplified: Since then , the inline-four has become one of the most common engine configurations in street bikes . Outside of the cruiser category , the inline-four is simply the most common configuration because of its relatively high performance-to-cost ratio .