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Bike Shop 3-5 / Week 04 / Thursday
4/6
Week 04 · Wheels, Tires and Air

Thursday

The press test
// What holds a tire up
⏱ about 15 min

Thursday: The Press Test

Raven's bike feels slow and heavy today. She has to pedal extra hard.

Rocket presses on her back tire. It flattens under his thumb!

"What do you notice?" Raven asks. "Is my tire firm?"

Nova dips down to look. "A press gives you a clue," she says. "What tool gives the true number?"

A quick clue

A press test is a quick clue about air.

If you can flatten the tire easily, it needs more air.

A press test is not exact.

The true check is a pressure gauge, used by a grown-up.

PRESS TEST STEPS
  • ?A grown-up holds the bike still.
  • ?Find the top of the tire.
  • ?Press down with your thumb.
  • ?Notice if the tire flattens.
  • ?Tell a grown-up what you felt.
WHY THIS EXERCISEHold, find, press, notice, then tell a grown-up.

Why air helps a bike roll

A tire flattens a little where it touches the ground.

A firm tire flattens less, so less of it touches the ground.

Less touching means less friction. The bike rolls more easily.

A soft tire flattens more. Rolling takes more work.

That is one reason the right air pressure matters.

FIRM OR SOFT?
  • Read the question.
  • Tap your answer.
Which tire flattens more where it touches the ground?
Why did Raven have to pedal extra hard?
What gives the true pressure number?
A firm tire touches the ground less. Does that make more or less friction?
WHY THIS EXERCISEA firm tire flattens less, so there is less friction and rolling is easier.
StatementTrue or false?
A press test gives an exact number.?
If a tire flattens easily, it needs more air.?
A soft tire makes rolling easier.?
A grown-up uses the pressure gauge.?
WHY THIS EXERCISEA press test is a clue. The gauge is exact. Firm tires roll easily.
Try it
Roll a firm ball across the floor.
Then roll a soft ball with the same gentle push.
Watch which one rolls farther.
Safety first
Roll the balls gently on an open floor.
Keep the path clear of people and pets.
Using a real tire? The bike stays still and a grown-up holds it.
BallHow far did it roll? (your own words)
firm ball
soft ball

Terrific testing! Tomorrow we compare fat tires and thin tires and review the week.

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