I use my phone on my motorcycle sometimes, and I always miss calls because I can't hear the ringtone through the headphones. Is there a way to change this setting so I can do that? Thanks.

Not unless it's an app that will allow it. Normal operation is to limit volume via any form of headset to keep ear damage down.

I dont know of any.

Ah that's annoying. Is there any way to get it to play at all? I tried it inside and the ringtone doesn't even play at all through the headphones.

I doubt it. I have a Jabra car speaker phone and thats the only thing I know that does allow ringing but it may be generated by the unit itself. I tried a wired ear bud and i get a low beep when a call comes in.
Not sure it would be loud enough to hear on the cycle.