Many replicas are based on the idea of a modern front-pannier arrangement, where the carrier is attached to the handle bars and front wheel. The carrier on an old-fashioned delivery bike, quite common at the time of the Wright Brothers, is instead bolted securely to the main frame.
This arrangement would be less likely to disturb the delicate balance point measurement as the rider lets go of the wheel (whilst riding at full speed with only one hand on the handlebars).
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