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Backpedaling on highest gear (11t) causes chain to pop up/out off at the front top part of the smallest cog. The bike and all components are very new and stock. This is a 1-by Shimano GRX Drivetrain. Any way to fix this or optimize the drivetrain?
Video: https://i.stack.imgur.com/jedJw.jpg
Rear Derailleur: Shimano GRX RX812 GS
Cassette: Shimano SLX M7000 11-42 11s
Crank: Shimano GRX RX600 40T
Chain: Shimano HG701 11-speed
I noticed some wear on top of cage, could it be related?
I think this might simply be unavoidable with such a chain line/angle (though it’s hard to tell from the video). If the chain is too long it might be exacerbating the problem. Make the chain shorter if it’s possible.
Those scratches on the rear derailleur look deep. Did you backpedal with force, causing the chain to tangle up everything? Was there an oopsie where you dropped the chain into the rear wheel spokes (limit screw too far out) and kept pedaling?
If the B-screw is not screwed in far enough the derailleur can hit the big sprockets, which could cause similar damage.
There is way too much lube on that chain. Wipe it down after lubing. Excess lube on the outside only attracts dirt.
