i am no expert in being a parent but i wanted to give my $0.02 anyway...

why not look for some baggies? at that age all he needs to do is to get more comfortable in his skin...when he gets out there and sees that the magority of riders are wearing lycra maybe he will too. but until baggies may be a good option? my hubby is not fearful of lycra but we always tend to grab a bite or run an errand after a ride so he will bring a pair of shorts to pull over the bike shorts so as not to look like a cycling-geek to the non-cycling world...

http://www.championcatalog.com/cgi-b...nbr=9020000000

something like these are lightweight/easy to carry and i am sure he probably already owns a pair