Originally Posted by FallsApart

More good responses, so thanks again. Seems like there's some resonance in others concerning the awkwardness of the situation, and I appreciate the comments.

RR - It happens all the time out here in Seattle - lots of popular bike routes covered with riders of mix school. Usually, though, the person who is jumping on to a group (myself included) will give a quick shot along the lines of "mind if i hop on back?" I'm comfortable with the etiquette on this side - I'll happily chat with a group as a solo - but it was odd to be on the other side as a guy who was lacking both courtesy and handling skills tried to jump on. Solution - slow and chat casually, i think. As in, "where are you riding from?" If he's seriously pushing, he'll push on, but if he's just looking for a group, he'll slow.

VG - totally right. I opened the door, and he jumped on. But it's totally awkward, right? Same thing happened on my ride - a few miles up, we were all at a stop light and the guy pushed for a yellow while i braked hard. But it takes a few miles to process.

Kimmo and Chas - There's the lesson - as UMD said, just talk to him early. Definitely had a little tunnel vision as we moved into the last, fast section of slight downhills.