Yeah, having the bail-out point be somewhere everyone can find their way home from is important. :)

I feel like the point is largely social; that is, if people wanted to bike optimally, they'd go alone, rather than inviting/joining an indeterminate number of friends. But that doesn't mean there is no biking goal; and it's frustrating to have a goal and get thwarted. Possibly that means the goal needs to be specified beforehand, so that the assumption is that everyone has agreed to aim for that goal. We already do this, i.e. name the route, estimate the mileage and state stops/food plans as appropriate. But if speed gets to be too much of a problem, the person calling the plan could specify further: I want to try for an average of N miles an hour, or I want to return by Y time which means N miles an hour, or whatever. People could then sort themselves out if they felt they weren't up to the specified goal. (Of course, I myself would be a little baffled trying to estimate my comfortable sustained speed, for example, and I imagine I'm not the only one...but it's a theory.) This would, of course, make the activity more exclusive, which means a social tradeoff not necessarily worth the gain.