7 Support Tickets in 4 Months — Now a Drivetrain Issue Stark Says is Tires. It Isn't.

[Erwin P]

Well how about a simple test then?
Take of the chain and rev to the speeds you have the vibrations. If it's still there it's the motor/gearbox.
If not, it's wheels/chain/suspension etc.

 

[Chaconne]

I offered, and Stark support said they wouldn't make a significant contribution.

How much would it be? Seems like a trivial thing? I would try @Erwin P 's suggestion then. You get a lot of suggestions here some might work some not. They are typically not engineered solutions but rather experience based. And that can sometimes be far more helpful.