Why a lighter wheel accelerates more easily
A solid wheel carries wood across its entire disk, including areas that do little to support the cart. A spoked wheel concentrates material in the hub, rim, and narrow beams joining them. The hub attaches to the axle; the rim meets the ground; the spokes carry forces between the two.
That matters not only because the cart weighs less. A wheel must also spin up whenever the cart starts or speeds up. Material near the rim is especially costly to accelerate because it travels in a circle far from the axle. Removing much of that material reduces the wheel’s rotational inertia—its resistance to changing how fast it spins.
The spokes make the open space work
The spokes are not decoration: they keep the rim connected to the hub and pass the cart’s load through the wheel. In a traditional wooden wheel, the spokes fit firmly between those parts, forming a rigid structure. The open spaces between them save weight without requiring the wheel to be a solid slab.
Spokes do not eliminate the work of hauling a load, nor do they make a cart fast by themselves. Their advantage is more specific: less wheel mass must be carried, and less rotating mass must be set in motion. With less effort spent moving the wheel’s own material, more of the pull can go toward moving the cart and its cargo.
