RIDE or "RIDE-IN"
The index and middle fingers of the dominant hand are "sitting" in the base
hand's "C handshape." Move the base hand forward a short distance with the
dominant hand "riding in" the base hand.
GET-IN:
GET-ON:
This sign is used for getting on things like a horse, a bike, a motorcycle, or a
bull.
RIDE-ON:
After "getting on," move the hand forward a short ways. If you are
riding on an animal, you can use an up and down rolling-type of movement:
If you are riding a bicycle or a
motorcycle then you just use a smooth forward movement:
If you mean "rider" as in someone who is riding a bus or other "sit on a seat"
conveyance, use this version: