We started out with a Burley Solo trailer
. Fine for a baby, extremely safe, good for naps, you can also haul all the stuff for a picnic. On the downside, your kid is disconnected from you and it slows you down. We bought the Solo because it's for one kid only: smaller and lighter. By the time we were ready to take Charlie for a ride, Maddie had graduated to the next item on my list.
When the kids got a little bigger (age 2), we switched to the Topeak BabySeat
which mounts over the rear tire. This one was my favorite and the kids both loved it too. Maddie used to sing me songs as we would ride along the bike trail. If you're a strong, well-balanced biker, you'll have no problem with this. It always made my wife nervous, but I loved it and so did both of our kids.
Next we got the Alley Cat Bicycle Trailer
, which turns your bike into kind of a tandem by adding a handlebar, wheel, seat and pedals behind your bike. There are lots of manufacturers that make these -- ours is kind of a cheap one. Kids aren't ready for this until they are 5 or 6 (IMO). I'm still kind of ambivalent about this one. Unless your kid can ride a bike without training wheels, it's kind of a PITA to have a kid back behind you, leaning to one side, and then having to compensate for this yourself.
Eventually, your kids will lose the training wheels and can start riding their own bicycles when you go for a ride.