Bike (retired)

I have two of Molly's bikes. One works fine. When I push the pedal, the pedal mechanism on the other bike it seems to stick. I am going to try some WD-40 and see if that helps. It may just need some lubrication. This bike is about 10 years old. The rear tires on my bikes don't bump into other parts. The chain that came with my bike fits properly.