Aerodynamics are as important with racing bikes as on a Formula One car - and wheels often cost more than £1,000 each.
With speeds so high, and wheels so large in diameter (70cm), wind resistance is a major factor.
One way of making wheels cut through the air more smoothly is to alter the design of the outer rim, which the tyre sits upon.
Deep-section rims, like a V in cross-section, mean the wheel is smoother at the point where it travels the fastest.
They also allow fewer spokes to be used, dramatically cutting wind resistance in this important area.
While a normal bike will have more than 30 spokes, most racing bikes have fewer than 20 and you can get wheels with just four.
To slice through the air even more effectively spokes are often as sharp as a knife - with predictably nasty finger injuries if a rider slips while adjusting a brake.
The wheels also clip off the bike in a split second so that a punctured tyre can be replaced as quickly as an F1 pit crew can change the wheels on a Ferrari.
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