What gear restrictions apply to youth riders?

On the road and track, youth riders are limited to a maximum gear, measured as the distance the bike travels for one full turn of the cranks (the "rollout"):

Gear checks must be done before the event on every rider who has a gear restriction, and further checks should be done afterwards. If your bike fails before the start, you can't use it. If it's found to be over the limit after the start, you should be disqualified.