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Electric cargo bicycles come in two configurations. The first are front-loader bikes, also known as bakfiets or Long Johns, which suspend a cargo box between the rider and the front wheel. The other layout is a midtail or longtail, which extends the rear end of the bicycle to accommodate more bodies and gear.
Both shapes have pros and cons. I’ve found that the bigger the rider, the more likely they want a front-loader bike, which in addition to hauling kids can be used as a big bin for yard equipment, tools, and more. However, you will need a garage or storage space and a very good and reliable lock system; they’re harder to maneuver and much heavier if you have to go over curbs or rough terrain; and they don’t feel particularly stable at slower speeds.
If you’re a smaller or lighter person, you may prefer a midtail or a longtail, which maneuver more like a regular bicycle. However, the weight is suspended on the back end and higher up, which makes some people nervous about dropping it. I own a longtail; I prefer the maneuverability, but it can be annoying making sure that everything is strapped down on a rack or in a pannier. If possible, I recommend making an appointment at your local bike shop to try several models before committing.