Some Rails also had a separate issue where the chainring cut into the chainstay, i don't think they ever worked out what caused it.these bolts worked their way loose on my 9.8xt about 5 months after I got it, Ive had it just over a year done about 700 miles and it looks lke they have done the same thing again! the give away is when the motor moves enough for the chainring to skim into the chain stay! cuts quite a nice groove... will be getting back to trek once the holidays are over to see what they do next!