I got a six-speed, 20 inch bike for my daughter when she was nine. They have a few models at REI. Some bike stores have them as well. Here’s an example:
There are gears in the back but not on the front, so it’s simpler to operate but still gives some options when on hills. Also has hand brakes, not coaster.
She rides it to school most days and we do occasional easy trail rides together. It’s pricier than something you’d get at Target, etc. but much better quality. It’s seen a lot of use and we’ve been happy with it.
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