My phone is in a pouch under my seat, and the road is super smooth, no bumps and such.
Just a thought, did you consider an Armband ? My wife runs with that stuff. I'm sure arm swing is less abusive on the phone than constantly moving lower body.
Now, don't go for the purple one, might not suit you, but the red one or black, are cool. Armpocket
My wife lugs her house key in it, some cash for a drink, and lock the headset cable on a side so it doesn't fly all over the place. It also prevents the phone from moisture damage. My wife killed her HTC by having it in a pocket. It actually corroded inside. And with such arm band, you can put the phone with a case.
Anyway, just a thought. And I'm glad the newer phone works at least better than the last one.
Have a good evening