I actually just started one of my other dogs (Audrey) riding today.  Like I mentioned before, she doesn't fit in the side carrier, but if it's just her and me, this works out ok.  She was a little nervous when we started moving, but once she felt the breeze in her face, she knew this was going to be fun.  We're starting out slow, but I'm excited to get another dog riding down the road...Mike

Note: Mike's other biker dog is Annie