Thanks all, especially for the quick replies. The -/+ dial is, indeed, for the front chainring and I probably will set it semi-permanently on the big ring, as suggested. I bought an e-bike to encourage me to cycle more and not to get hot and sweaty, so it will be used in assist mode most of the time. Even so, after two short trips I'm discovering aches in muscles I'd forgotten I had. Just what the doctor ordered!