You can limit all distances to a specific capacity.

OR you can set a capacity for each distance:

In the capacity settings, you can also enable the waitlist when your race is full.

1. Click “edit” next to the distance on which you would like to enable the waitlist.
2. Check the box in the column “Enable Waitlist When Filled”
3. You can display the waitlist on your registration page for everyone to see by checking the box in the column titled “Display Waitlist Icon?”.
4. Do not forget to click “update” to save your settings.