Dan,
I saw a post for a BOB trailer with a 16" electrically driven wheel. Now I'm getting seriously interested. It looks to me like you could attach the BOB to any bike (or trike) that has a QR rear wheel but, of course, I don't have any experience with either BOB trailers or e-assist. Does this sound like a good idea to you? I'm thinking that Mrs. Grouch might have such a booster in her future.
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My greatest fear is all of my kids standing around my coffin and talking about "how sensible" dad was.