This is a good question. As of now there doesn't seem to be anything official for riding an animal companion to use its fly speed. I'm going to be GMing a one-shot tonight and one of my players wants to play a druid goblin with a bird animal companion. We'll be playing at level 7, so his bird will be at least one size larger than his goblin, however because of that "Riding Animal Companions" rule he technically can't ride it to use its fly speed.
However, from a mechanical standpoint, a mature bird has a strength modifier of 3, which would make it able to carry 8 Bulk before becoming Encumbered. A typical small sized creature (like a goblin) is considered to be 3 Bulk before you account for its equipment. Tack for a companion is 1 Bulk. So if the bird is wearing tack and a small PC doesn't go over 4 Bulk with their equipment, they'd be within the mature bird companion's Bulk limit before making it Encumbered.
As a GM, I personally don't see anything wrong with allowing my player to ride his bird, so long as they stay within the companion's bulk limit. Most enemies will still be able to retaliate without issue during encounters, unless they have zero ranged capability. By level 7 certain classes will already have access to spells or equipment that allows them to gain a fly speed anyway, so I don't see anything broken about riding a flying companion. They'll only be able to do so effectively outdoors or in larger/taller spaces. In addition, that player will have to keep spending actions to Command an Animal in order to keep benefiting from their companion's fly speed, not to mention Nature checks if they don't have the Ride general feat.
The entry for the Roc in the Bestiary hints at the possibility of capturing and training a Roc as a "flying mount," so I don't really see the harm in allowing a player to ride their flying companion.
Another thing to note is that while flying, that bird companion will more than likely be prioritized over the player for ranged attacks. And the bird is somewhat squishy, being only at 60 hit points at level 7. A character putting themselves in that situation might make it easier for an enemy to "kill two birds with one stone".
This is a good question. As of now there doesn't seem to be anything official for riding an animal companion to use its fly speed. I'm going to be GMing a one-shot tonight and one of my players wants to play a druid goblin with a bird animal companion. We'll be playing at level 7, so his bird will be at least one size larger than his goblin, however because of that "Riding Animal Companions" rule he technically can't ride it to use its fly speed.
However, from a mechanical standpoint, a mature bird has a strength modifier of 3, which would make it able to carry 8 Bulk before becoming Encumbered. A typical small sized creature (like a goblin) is considered to be 3 Bulk before you account for its equipment. Tack for a companion is 1 Bulk. So if the bird is wearing tack and a small PC doesn't go over 4 Bulk with their equipment, they'd be within the mature bird companion's Bulk limit before making it Encumbered.
As a GM, I personally don't see anything wrong with allowing my player to ride his bird, so long as they stay within the companion's bulk limit. Most enemies will still be able to retaliate without issue during encounters, unless they have zero ranged capability. By level 7 certain classes will already have access to spells or equipment that allows them to gain a fly speed anyway, so I don't see anything broken about riding a flying companion. They'll only be able to do so effectively outdoors or in larger/taller spaces. In addition, that player will have to keep spending actions to Command an Animal in order to keep benefiting from their companion's fly speed, not to mention Nature checks if they don't have the Ride general feat.
The entry for the Roc in the Bestiary hints at the possibility of capturing and training a Roc as a "flying mount," so I don't really see the harm in allowing a player to ride their flying companion.
Another thing to note is that while flying, that bird companion will more than likely be prioritized over the player for ranged attacks. And the bird is somewhat...
Note that an animal companion is a minion, and you naturally have the ability to spend an action to control your minion, getting two actions. Others pointed that out and said, that would likely mean you are not supposed to need to roll to control your animal companion, since you don't for other minions.