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Cycling

For the grown-up beside a child who loves cycling.

The child's own door is Cycling on Spark & Anvil.

There is no Whetstone tool or course for cycling yet, so this page is the sideline card and your child's ladder.

The sideline card

Three numbers to notice

  1. The gears: teeth on the front ring divided by teeth on the back cog. With 44 and 22, the back wheel turns twice for each turn of the pedals.
  2. The size on the side of the tyre, like 50-406: 50 mm wide, on a rim whose bead seat is 406 mm across, the usual 20-inch wheel.
  3. One turn of a 20-inch wheel rolls about 1.6 metres: the wheel’s height, about half a metre, times π.

On the way home, ask: “Which gear did your legs like best on the hill?”

Ask because you are curious, and let any answer stand. Print this page for a half-page card.

Numbers checked against: ISO 5775 / ETRTO bicycle tyre and rim sizes; worked by hand, lines 1 and 3 (44 ÷ 22 = 2; 506 mm × π ≈ 1.59 m)

Your child's ladder · on Spark & Anvil

The same idea at every age

  1. Ages 3–5Not made yet
  2. Ages 6–8One Turn, One Trip Around
  3. Ages 9–14Average Speed in a Triathlon
  4. Ages 15–18Watts per Kilogram

Your child will meet this idea again at every age. The sideline card is the part for you.