Di2 electronic shifters
Before I started on shift, the other mechanic guy Richard said he saw a couple of these that had failed due to water ingress. However, we didn’t see this problem later on and it was still wet. I surmise that there is more than one design for the place where the water leaked in
How to avoid this:
Don’t buy electronic shifters for a year or two until they’ve got the problems sorted out
Common Mechanical Problems On London Edinburgh London