Buy Online Mongoose Mode 270 Boy’s Freestyle Bike. Mode 270 is one of the best Freestyle Boy’s Bikes offered by Mongoose Bikes. The price of the Mongoose Mode 270 Boy’s Bike is $120 with a 4-star rating. The frame of Mode 270 Boy’s Mongoose Bike is made of steel. Brakes style is U brake clipper. Mode 270 is a single speed with steel handlebar spin 360.