Changed another set of bearings along with several other maintenance actions on @Nomad , Herb's '13 GT today, 50k miles. Below is a photo of the bearings with seals removed. The bearings 'seemed' to turn freely, but it can be really hard to check them. Changed them as preventive maintenance. The grease in both bearings was dry, clay like, and there was rust. I've changed over a dozen sets of bearings, most as preventive maintenance, and almost all NEEDED changing. I haven't kept records to know for sure how many miles each set had on them; if I had to guess I'd say around 50k miles. We got lucky with Herb's bike, those bearings would not have lasted much longer. When asked I've recommended changing bearings at 35k-40k miles; it may be the best $20 you've spent on your bike.