Grab a Ride: Ride. When you successfully maintain a grapple on an opponent of a larger size category than you, you can ride them around like a horse. To do so, you may make a Ride check with a DC equal to 10+ the target’s CMD. If successful, you mount the target and force them to move up to half their speed in a legal direction you choose. You cannot force the target to attack its allies or do anything other than allow you to ride them.
-Max Porter Zasada