Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Wobbly, doesn't fit some bikes and has no head support for child

We really liked the concept of this seat, but it just didn't work out. For one, our bike's stem could not be raised the required 3/4 inches, so I had to move the handlebars slightly off the top of the stem. The people at our local bike shop found this terrifying.The seat wobbles and rattles a bit. It seems secure, but the feeling is unnerving. I emailed ibert and they said some people had put duct tape in to stabilize it, but why wouldn't they fix this themselves?Aside from the difficulty of getting on the bike with so little space between the child's seat and yours, the biggest reason we ended up returning it is because there's NO support for the child's head when they fall asleep. Our daughter would last about 15 minutes before she fell asleep, then it was difficult to support her head and ride at the same time.All the bike shops I went to thought that these front seats were a bad idea and now I see why.