What’s the best convertible bike trailer/stroller on the market?

I’m a year-round bike commuter and errand runner (this summer I made a tank of gas last four months). However, the arrival of my son has altered my lifestyle. How old does he have to be before he can ride in a trailer? And which trailer do you recommend? I'd like it to convert to a stroller relatively easily. Also, we’d like a double in case we are lucky enough to adopt a second child. Either that or just to accommodate enough groceries. Karin Mountain View, California


Interesting question. As far as “how old," in my view it would be the age where the child can support his/or her head while wearing a helmet. And the rub is, helmets don’t fit infants younger than one year. So that’s your cut-off point. When your son is one, you can put him in a trailer. I would absolutely not advocate placing a child carrier in some sort of trailer and trying to make that work. You’ve really seen people try that?

In short, for a while you’ll need to enlarge your carbon footprint to keep your son safe.

There aren’t a zillion “convertible" trailers out there, but some do exist. Maybe the best is the Baby Jogger Switchback stroller/trailer ($579; babyjogger.com), which converts easily from stroller to trailer without a conversion kit or tools. And the front wheel that’s used in stroller mode fits neatly into an on-board pocket. It also will seat two. Burley’s D’Lite ($460; burley.com) is seen by many as the best child bike trailer on the market. It converts to a stroller with the purchase of a $60 kit. Or, Schwinn’s Joyrider ($380; schwinnbike.com) offers trailer/stroller functionality at a bit lower price. Not quite as spiffy as the Baby Jogger or Burley units, but a solid trailer.

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