How Can A Faster Rider Aid A Slower Rider On A Long Ride? For the context of this question, two people are trying to get from point A to point B (and back) where the only viable means of transportation is bicycle (and a tandem bicycle / electric bicycles are not available).  The distance between the two points is 20km (40km round trip).  Preparation time is limited, we could go visit point B next week, but it is unlikely we'll ever find ourselves in this part of the world again.  The bicycles we do have available would be rented, mid-ranged commuter style bicycles.

We'd both like to make this trip.  One of us is a daily commuter (15km each way) who is used to longer rides of 40-50km on the weekends, the other rides rarely and has never gone more than 3km at a time.  Even at a slow pace, 40km would be far more than this rider could do comfortably.

What tips/techniques (if any) are there that would allow the stronger rider to complete the trip as comfortably as possible?  

Thanks
Novices I've ridden with are surprised and pleased that I ride behind them.


They set the pace
I can watch what they're doing
I can ride close (enough to talk) without being too close (i.e. without colliding)
I can recommend which gear they change and when
I keep car traffic off their tail (e.g. by my using arm-signals to the car to say "slow down" or "please overtake", and by riding closer to the centre line than the bike in front of me does, etc.)