[Paul_E_D]

The 125 shouldn't be pushing or sliding anywhere. That's a sign (along with the chatter) that it's too stiff. Of course, the rider is a factor that can be too stiff as well!

rear chatter is unusual. I'm not sure what's up there. It's not binding is it?

You won't be able to ride around it without losing all your fillings. The 125 is stiff as a board and chatter is punishing.