Cargo ebikes can be a great alternative to the family car when hauling groceries or doing the school run. But they can be a bit wobbly at slow speeds. Startup Tarran is aiming for improved stability with auto-deploying landing gear.

  • litchralee@sh.itjust.works
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    5 days ago

    Most people riding bicycles already deploy their retractable landing gear when preparing to touch down: they’re called legs.

    And while maybe there’s an argument to be made that a properly-adjusted bicycle might not allow both feet to touch the ground while still seated, this contraption has some serious limitations. The most egregious is that landing gear – like on aircraft – are only effective when fully extended. But whereas all runways are laterally level, bicycling surfaces offer no such guarantee.

    Imagine riding this cargo bicycle on a curve which has a cant (aka superelevation, or banking, or cross slope), then slowing down for a pedestrian or even stopping. A two-wheel bicycle naturally finds the lean angle to balance the centripetal force against the gravitational force, irrespective of the relative angle to the ground surface. But fully-extending landing gear forces the bicycle to be perpendicular to the ground surface, against the mandatory lean angle to balance the forces. And there doesn’t seem to be a provision for partially extending one side of the landing gears to account for the cross slope. If the perpendicular arrangement puts the center of gravity beyond the stubby extended wheels, the bike will fall over.

    Tricycles will also force the same perpendicular alignment, but: 1) does so at all times, on straightaways and curves, so this isn’t a surprise to the rider, and 2) tricycle wheels are set wider than these stubby “landing gear” wheels, which is important if the cargo load is substantial (or heavy or too high) and could topple the bicycle when stopping on a curve.

    This contraption is akin to bicycle training wheels: too narrow to provide actual safety benefits, while also being outright detrimental towards developing the motor skill necessary to pilot a cargo two-wheeler with its unique qualities.