Simplify the following text for a Grade 4 native English-speaking person.
Original: Children 's tricycles and most adult tricycles made for the recreational market use the upright layout . From a design point of view , the difference between children 's and adult tricycles is that whereas children 's tricycles are usually direct-drive and have no brakes , adult trikes usually have a gear-drive with multiple speeds and front and rear brakes .
Simplified: Tricycles can be called trikes .