The Radio Flyer 4-in-1 trike is adjustable in so many ways... it grows with your toddler! My son is almost 2 years old and we've found that the Radio Flyer tricycle is a great alternative to a traditional stroller. Here's my review of this toddler trike - including the pros and the cons.The Radio Flyer 4-in-1 trike is adjustable in so many ways... it grows with your toddler! My son is almost 2 years old and we've found that the Radio Flyer tricycle is a great alternative to a traditional stroller. Here's my review of this toddler trike - including the pros and the cons.