This is a Trail a Bike that attaches to the seatpost of a lead bike and allows the child to peddle on their own. It has 5 speeds and allows them to shift themselves. It has a bracket that attaches to the lead bike's seatpost that allows for a quick attach/detach for transport. I've pulled all of my kids, even on trails with no problems.
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NOTE: You need to be a proficient mountain biker to pull a child on a trail.