Quote from esbee on Sep 25^th, 2011, 5:17pm:

 
That depends upon what he needs electric assist for...  are there hills he simply can't climb due to physical limitations, or long distances he needs to go and needs the help?  Tell more about why you/he want to do this....
 
Here's a fairly complete description of a Bionx system, courtesy of Lightfoot Cycles...  http://www.lightfootcycles.com/bionx.php
 
Paul

Thanks, Susan -- I might also be inclined to not bother with the expense of an electric assist, and just encourage him to get out and ride...  by doing it regularly, this distance capability will increase, and the hills will get easier.  None of us start out instantly able to do 30/50/100+ mile rides -- my first GDB club ride was 20 miles, on my EZ-1, and I was exhausted...  
 
Do the two-mile route twice... then three times.... Plan out a 5 mile route, and just go do it.  Then plan to do it twice, as a challenge!   Increased distance capability comes from regular riding, and pushing yourself to go longer.  It's 9 miles around White Rock Lake, with a couple of climbing spots...  
 
A nice thing about a trike is you can go as slow as you need to up hills and not worry about balancing.  You/he might also consider looking into some inexpensive "Power Grips" for the pedals (or some combo platform/SPD pedals and inexpensive SPD shoes), so you can get a bit of 'pull' from the pedals instead of just a push.  It will help...